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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 8 — Apr. 22, 2013
  • pp: 9365–9376
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The potential of Yb:YCa4O(BO3)3 crystal in generating high-energy laser pulses

Junhai Liu, Qibiao Dai, Yong Wan, Wenjuan Han, and Xueping Tian  »View Author Affiliations


Optics Express, Vol. 21, Issue 8, pp. 9365-9376 (2013)
http://dx.doi.org/10.1364/OE.21.009365


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Abstract

The passive Q-switching laser performance of Yb:YCa4O(BO3)3 is studied with crystals cut along the principal optical axes. Using a Cr4+:YAG saturable absorber with initial transmission of 93.7% and an output coupler of transmission of 40%, efficient Q-switched laser operation is achieved with a X-cut crystal, generating an output power of 2.14 W at a pulse repetition rate of 4.5 kHz. The resulting laser pulse is 9.3 ns in duration, with the energy being as high as 476 μJ and the peak power amounting to 51.2 kW. The results demonstrated in this work reveal the great potential of this crystal in developing high-energy compact pulsed lasers.

© 2013 OSA

1. Introduction

Yb:YCa4O(BO3)3 (Yb:YCOB), along with its isomorphic compound, Yb:GdCa4O(BO3)3 (Yb:GdCOB), are among the few Yb laser crystals that have been known since the early stage in the development of Yb lasers [1

1. D. A. Hammons, J. M. Eichenholz, Q. Ye, B. H. T. Chai, L. Shah, R. E. Peale, M. Richardson, and H. Qiu, “Laser action in Yb3+:YCOB (Yb3+:YCa4O(BO3)3),” Opt. Commun. 156(4-6), 327–330 (1998). [CrossRef]

4

4. F. Augé, F. Balembois, P. Georges, A. Brun, F. Mougel, G. Aka, A. Kahn-Harari, and D. Vivien, “Efficient and tunable continuous-wave diode-pumped Yb3+:Ca4GdO(BO3)3 laser,” Appl. Opt. 38(6), 976–979 (1999). [CrossRef] [PubMed]

]. Although efficient continuous-wave (cw) laser action was achieved with Yb:YCOB under diode pumping in as early as 1999, generating an output power of ~0.45 W with a slope efficiency of 73% [2

2. H. Zhang, X. Meng, P. Wang, L. Zhu, X. Liu, R. Cheng, J. Dawes, P. Dekker, S. Zhang, and L. Sun, “Slope efficiency of up to 73% for Yb:Ca4YO(BO3)3 crystal laser pumped by a laser diode,” Appl. Phys. B 68(6), 1147–1149 (1999). [CrossRef]

], since then this laser crystal had not attracted much attention. This situation lasted until 2007, when a cw output power of 2.8 W was generated with a diode pumped Yb:YCOB laser [5

5. H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt. 46(12), 2292–2296 (2007). [CrossRef] [PubMed]

]. Shortly thereafter, the cw laser performance of this monoclinic crystal was evaluated thoroughly by use of samples cut along the three principal optical axes, with output power generated amounting to 7.3 W [6

6. J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B 91(2), 329–332 (2008). [CrossRef]

,7

7. J. Liu, H. Zhang, J. Wang, and V. Petrov, “Output-coupling-dependent polarization state of a continuous-wave Yb:YCa4O(BO3)3 laser,” Opt. Lett. 32(20), 2909–2911 (2007). [CrossRef] [PubMed]

]. More importantly, complex polarization state varying behavior was observed in the laser oscillation generated with a Y-cut Yb:YCOB crystal [7

7. J. Liu, H. Zhang, J. Wang, and V. Petrov, “Output-coupling-dependent polarization state of a continuous-wave Yb:YCa4O(BO3)3 laser,” Opt. Lett. 32(20), 2909–2911 (2007). [CrossRef] [PubMed]

]. Despite the relatively low thermal conductivity (~2 Wm−1K−1) of Yb:YCOB, thin-disk lasers based on this crystal have been realized in efforts of power scaling, producing an output power of ~100 W [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

,9

9. O. H. Heckl, C. Kränkel, C. R. E. Baer, C. J. Saraceno, T. Südmeyer, K. Petermann, G. Huber, and U. Keller, “Continuous-wave and modelocked Yb:YCOB thin disk laser: first demonstration and future prospects,” Opt. Express 18(18), 19201–19208 (2010). [CrossRef] [PubMed]

]. A wide tuning range of 997−1092 nm was also obtained with the thin-disk laser [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

]. Due to its wide emission bandwidth, the Yb:YCOB crystal is very attractive in generating ultrashort laser pulses by mode-locking technique. In recent years a lot of work has been conducted on mode-locked Yb:YCOB lasers, with the pulse duration reduced from the initial 210 fs to the latest 35 fs [10

10. G. J. Valentine, A. J. Kemp, D. J. L. Birkin, D. Burns, F. Balembois, P. Georges, H. Bernas, A. Aron, G. Aka, W. Sibbett, A. Brun, M. D. Dawson, and E. Bente, “Femtosecond Yb:YCOB laser pumped by narrow-stripe laser diode and passively modelocked using ion implanted saturable-absorber mirror,” Electron. Lett. 36(19), 1621–1623 (2000). [CrossRef]

13

13. A. Yoshida, A. Schmidt, V. Petrov, C. Fiebig, G. Erbert, J. Liu, H. Zhang, J. Wang, and U. Griebner, “Diode-pumped mode-locked Yb:YCOB laser generating 35 fs pulses,” Opt. Lett. 36(22), 4425–4427 (2011). [CrossRef] [PubMed]

].

In addition to possessing wide emission spectra that enable the generation of mode-locked ultrashort laser pulses, the Yb:YCOB crystal is also known to have a long fluorescence lifetime (2.2 ms [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

]) and small stimulated emission cross sections (~0.3−0.4 × 10−20 cm2 at ~1030−1040 nm for E//Z [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

]) which amount only to less than one fifth that of Yb:YAG (2.1 × 10−20 cm2 [14

14. W. Koechner, Solid-State Laser Engineering (Springer, 2006).

]), these features can greatly benefit Q-switching laser operation owing to the large energy storage capacity. Up to now, however, studies on the Q-switching laser performance of Yb:YCOB are still very limited, the only relevant work conducted is the demonstration of a passively Q-switched laser, with InGaAs quantum wells serving as the saturable absorber, producing an output power of 1.15 W (pulse energy of 165 μJ and duration of 100 ns) [5

5. H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt. 46(12), 2292–2296 (2007). [CrossRef] [PubMed]

]. In comparison with the performance of passively Q-switched lasers based on other Yb crystals [15

15. A. Brenier, C. Tu, Z. Zhu, and J. Li, “Dual-polarization and dual-wavelength diode-pumped laser operation from a birefringent Yb3+-doped GdAl3(BO3)4 nonlinear crystal,” Appl. Phys. B 89(2-3), 323–328 (2007). [CrossRef]

18

18. J. Liu, Y. Wan, Z. Zhou, X. Tian, W. Han, and H. Zhang, “Comparative study on the laser performance of two Yb doped disordered garnet crystals: Yb:CNGG and Yb:CLNGG,” Appl. Phys. B 109(2), 183–188 (2012). [CrossRef]

], the capacity of Yb:YCOB in generating Q-switched laser pulses has not been effectively explored. Therefore, more efforts need to be made to evaluate the real potential of this monoclinic Yb crystal in applications for making Q-switched laser devices.

In this paper we report on the passive Q-switching laser performance of Yb:YCOB crystal, demonstrated with Cr4+:YAG crystals utilized as saturable absorber. By properly selecting the initial transmission of the Cr4+:YAG crystal (T0) and the output coupling of the resonator (T), we realized efficient Q-switched laser operation with Yb:YCOB crystal, generating laser pulses of energy as high as 476 μJ, much higher than obtained with most other Yb crystals under similar operational conditions.

2. Description of experiment

As is known, Yb:YCOB is a monoclinic biaxial crystal of very low symmetry (point group m), its spectroscopic properties and cw laser performance exhibit strong anisotropy [6

6. J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B 91(2), 329–332 (2008). [CrossRef]

,8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

,19

19. A. Aron, G. Aka, B. Viana, A. Kahn-Harari, D. Vivien, F. Druon, F. Balembois, P. Georges, A. Brun, N. Lenain, and M. Jacquet, “Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material,” Opt. Mater. 16(1-2), 181–188 (2001). [CrossRef]

]. To account for such anisotropy in evaluating the Q-switching laser performance, we prepared three crystal samples cut along the principal optical axes (X, Y, and Z) from the same crystal boule, with an identical thickness of 2.88 mm and a square aperture of 3.3 mm × 3.3 mm. The Yb ion concentration of the Yb:YCOB crystal was 8.8 × 1020 cm−3 (20 at. %). Several Cr4+:YAG crystals were utilized as saturable absorbers for passive Q-switching action, their initial transmissions were T0 = 97.5%, 94.4%, 93.7%, and 92.0%, respectively. These Cr4+:YAG plates were coated for antireflection at 1.06 μm on both faces. The laser resonator was formed by a plane reflector and a concave mirror of radius-of-curvature of 50 mm, which served as the output coupler. The plane reflector was coated for high reflectance (>99.9%) at 1030−1200 nm and high transmittance (>98%) at 820−990 nm. A group of output couplers were used in the optimization of the Q-switched laser operation, with output couplings ranging from T = 10% to T = 50%. To achieve efficient laser action, the uncoated Yb:YCOB crystal was held in a water-cooled copper block which was maintained at a temperature of 5 °C, and was positioned close to the plane reflector inside the resonator, while the Cr4+:YAG plate was inserted between the laser crystal and the output coupler. The physical cavity length was 28 mm. The pump source used was a fiber-coupled diode laser (fiber core diameter of 200 μm and NA of 0.22) emitting unpolarized radiation with center wavelength varying from 968 to 971 nm, which was dependent on the output power level. The emission bandwidth of this diode laser was at most 3 nm. The pump radiation was focused first by a focusing optics and then delivered through the plane reflector onto the laser crystal with a beam spot radius of approximately 100 μm. A digital oscilloscope (Infiniium DSO80304B, Agilent Co. Ltd.), with the bandwidth of 3 GHz and sampling rate up to 40 GS/s, was employed to monitor the laser pulses and measure the pulse parameters. The laser emission spectra were measured by use of a spectrometer (AvaSpec-3648, Avantes B.V.) with a resolution of 0.3 nm.

3. Results and discussion

For efficient laser action, the Yb:YCOB crystal was actively cooled with cooling water of temperature of 5 °C, in order to diminish the impact of thermally induced resonant losses inherent to a quasi-three-level laser. With the cooling water temperature rising from 5 °C to 20 °C, the laser efficiency would be reduced by about 5−10%, measured at an output power of 1.0 W when the laser was operated in cw mode. Without active cooling, significant temperature rise would occur within the pumped region inside the crystal, leading to an increase in the transition linewidth (Δωa) as a result of the strengthened homogeneous phonon broadening, and hence reducing the stimulated emission cross section that is inversely proportional to Δωa [20

20. A. E. Siegman, Lasers (Mill Valley, California: University Science, 1986).

]. Such variation of stimulated emission cross section with temperature has been confirmed experimentally in a study on Yb:YAG crystal [21

21. J. Dong, M. Bass, Y. Mao, P. Deng, and F. Gan, “Dependence of the Yb3+ emission cross section and lifetime on temperature and concentration in yttrium aluminum garnet,” J. Opt. Soc. Am. B 20(9), 1975–1979 (2003). [CrossRef]

].

The passive Q-switching laser performance of Yb:YCOB was studied with the X-, Y-, and Z-cut crystal samples in the simple plano-concave resonator, under operational conditions of different combinations of T0 and T. It was found experimentally that the X-cut crystal was advantageous over the Y- and Z-cut samples, in generating average output power as well as pulse energy. With the X-cut crystal efficient Q-switched laser operation could be obtained with an output coupling that varied from T = 10% to T = 50%; in the case of T < 10%, efficient laser action was also attainable, but on a risk of possible damage to the internal elements under high-power conditions. The Q-switched laser operation achieved with the Y-cut crystal proved to be less efficient, and the highest output coupling allowed to be used was limited to T ≤ 30%. With the Z-cut crystal, however, no stable Q-switching laser action could be obtained, even in the case of T0 = 97.5%, which was the highest initial transmission of the Cr4+:YAG saturable absorber available in the current experiment. For Z-cut Yb:YCOB crystal, laser oscillation (cw) could only be realized with polarization parallel to the X axis (E//X) [6

6. J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B 91(2), 329–332 (2008). [CrossRef]

], the stimulated emission cross section for E//X proves to be even lower than for E//Z, amounting to approximately 0.25 × 10−20 cm2 [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

]. This implies that a Cr4+:YAG saturable absorber of still higher T0 might be required to generate passive Q-switching laser action.

In general, high-energy short-duration laser pulses in passively Q-switched operation can only be obtained under conditions of high T and low T0. According to this, the optimum combination of T and T0, which could be used for the X-cut Yb:YCOB laser, was T = 40% and T0 = 93.7%. In this case, the absorbed pump power required for reaching laser threshold was measured to be Pabs = 4.2 W, much higher than measured in the other two cases, due to the high overall losses. Despite the high lasing threshold, a maximum output power of 2.14 W was generated with a slope efficiency still amounting to 65%.

In our experiment, efforts were also made to operate the Q-switched X-cut Yb:YCOB laser under conditions of T > 40% and T0 < 93.7%. However, with a coupler of T = 50%, the lasing threshold was found to be too high; while damage was easy to occur on the surface of the laser crystal or the Cr4+:YAG plate when a saturable absorber of T0 = 92.0% was used. Due to the low stimulated emission cross section (maximum value of 0.46 × 10−20 cm2 for the laser emission band [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

]), a very large energy fluence is expected to exist inside the resonator for efficient Q-switched laser action, making it very likely that damage occurs to the surface of intracavity elements. In order to prevent such damage while employing a saturable absorber of lower T0 to produce higher pulse energy from the Yb:YCOB laser, an output coupler of larger radius-of-curvature (e.g., R2 = 100 mm) and of suitably high transmission should be utilized to form the plano-concave resonator with longer cavity length. In this way, the oscillating mode size will become larger, whereas the resulting laser pulse duration will be longer, this will greatly reduce the internal circulating intensity while the energy fluence remains unchanged, and hence reduce the risk of intracavity element damage. Evidently, to keep mode matching with the enlarged laser mode size, the pump beam spot should also be expanded accordingly. On the other hand, more pump power is needed in this case to realize equally efficient laser operation.

The passive Q-switching laser performance achieved with the Y-cut crystal, as illustrated in Fig. 1(b), turns out to be inferior to that demonstrated with the X-cut crystal. This seems to be in controversy with the previously reported results for cw laser operation, where the Y-cut crystal proved to be even slightly advantageous over the X-cut one [6

6. J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B 91(2), 329–332 (2008). [CrossRef]

]. Among other factors, the difference in optical quality between the X- and Y-cut samples used in the current experiment, which were prepared from different parts of the crystal boule, might be responsible for the less efficient operation with the Y-cut crystal. One direct evidence for this is the lasing threshold for Q-switched operation measured in the case of T = 20% and T0 = 94.4%, which was considerably higher for the Y-cut crystal. Given the same stimulated emission cross section involved in the two cases (E//Z), a higher threshold implies greater dissipative losses arising from the Y-cut crystal. In the case of T = 10% and T0 = 97.5%, the maximum output power measured at Pabs = 7.5 W, the highest pump power applied in this case, was 3.51 W, the corresponding optical-to-optical and slope efficiencies being 47% and 63%, respectively. The highest output power, produced in the pulsed operation achieved under conditions of T = 20% and T0 = 94.4%, was 2.75 W, the slope efficiency being 62%.

It can also be seen from Fig. 1 that, in each case, the increase of output power with Pabs exhibited no tendency of rolling off at the highest pump power, implying that there was still more room for further power scaling. To prevent any possible crystal fracturing of the Yb:YCOB samples, we limited the highest pump power absorbed in the crystal to be 7.8 and 7.5 W, for the X- and Y-cut crystals, respectively.

In general, the transverse mode structure of a laser is determined mainly by the resonator configuration, the mode matching of pump with laser beam, and the specific laser material used; it also depends to some extent on pump power or output power level. For the Yb:YCOB laser studied in our experiment, its beam pattern was almost independent of either the output coupling or the operational fashion (cw or Q-switched). Illustrated in Fig. 2
Fig. 2 A typical laser beam profile measured at an output power of 1.0 W for the X-cut Yb:YCOB laser operating in the cw mode.
is a typical beam profile, measured at an output power of 1.0 W for the X-cut Yb:YCOB laser operating in cw mode. The corresponding beam quality factor, M2, was measured to be 2.19 and 2.27, for the horizontal and vertical directions, respectively. This indicates the presence of higher-order transverse modes in the laser oscillation. Nevertheless, the laser intensity can still be well fitted to a Gaussian distribution, in both the horizontal and vertical directions, as shown in this figure. For the resonator configuration used in this laser, the fundamental mode radius is calculated to be about 90 μm at the position of the laser crystal, in the absence of thermal lensing effect, which is somewhat smaller than the pump beam spot radius (~100 μm). With the strengthening of thermal lensing in the laser crystal, the fundamental mode radius will be reduced to some extent, facilitating the oscillation of higher-order transverse modes.

In Q-switched or cw laser operation under certain conditions of T and T0, the oscillation wavelengths varied only slightly with pump power. Illustrated in Fig. 3
Fig. 3 Q-switched and cw laser emission spectra measured at Pabs = 4.78 W for the X-cut crystal (a), and at Pabs = 4.71 W for the Y-cut crystal (b).
are the laser emission spectra measured at an intermediate pump power for cw or Q-switched operation achieved with the X- or Y-cut crystal under different conditions. These emission spectra were recorded for a time average of many laser pulses, depending on the response time of the spectrometer employed. One sees that the emission spectra for cw operation consist of many discrete peaks or lines which are roughly equally spaced, such modulation resulted from the effect of some etalons existing inside the resonator (e.g., formed by the uncoated crystal surface and the plane cavity mirror), with the separation between two adjacent lines corresponding to the free spectra range. In the case of passively Q-switched operation, the structure of laser emission spectrum was determined not only by such etalon effect, but also by the discrimination of longitudinal modes accompanying the passive Q-switching process [24

24. O. Svelto, Principles of Lasers (Springer, 2010).

]. Due to the presence of the latter mode selecting action, the laser emission spectrum of the passively Q-switched operation is usually narrower than its cw counterpart. In fact, under some certain circumstances only a single longitudinal mode can survive from this mode discrimination effect during the passive Q-switching process [16

16. J. Liu, V. Petrov, H. Zhang, J. Wang, and M. Jiang, “Efficient passively Q-switched laser operation of Yb in the disordered NaGd(WO4)2 crystal host,” Opt. Lett. 32(12), 1728–1730 (2007). [CrossRef] [PubMed]

,25

25. J. Liu, X. Tian, Z. Zhou, K. Wu, W. Han, and H. Zhang, “Efficient laser operation of Yb:Lu3Ga5O12 garnet crystal,” Opt. Lett. 37(12), 2388–2390 (2012). [CrossRef] [PubMed]

,26

26. J. Liu, X. Tian, K. Wu, Q. Dai, W. Han, and H. Zhang, “Highly efficient Q-switched laser operation of Yb:Y3Ga5O12 garnet crystal,” Opt. Express 21(3), 2624–2631 (2013). [CrossRef] [PubMed]

]. In cw laser operation for T = 10%, the oscillation wavelengths measured for the two crystal samples were very close: 1039.4−1048.0 nm (X-cut) and 1039.8−1046.6 nm (Y-cut). In Q-switched operation achieved with the X-cut crystal, the laser emission range shifted to 1033.8−1040.7 nm (T = 10%, T0 = 97.5%), 1031.3−1033.2 nm (T = 20%, T0 = 94.4%), and 1031.0−1032.7 nm (T = 40%, T0 = 93.7%). Similarly, this emission range measured for the Y-cut crystal was 1035.0−1041.7 nm (T = 10%, T0 = 97.5%) and 1026.6−1033.5 nm (T = 20%, T0 = 94.4%), as shown in Fig. 3. The multi-longitudinal-mode oscillation obtained with the passively Q-switched Yb:YCOB laser reveals the strong mode competition, due to the very close gain seen by these individual axial modes. For the laser resonator of 28 mm in cavity length, the axial mode separation is 0.018 nm (for the oscillation at 1030 nm). Therefore, the laser emission bands, about 2−7 nm in width measured in Q-switched operation, correspond to approximately 110−390 longitudinal modes. A tendency is also clearly shown in Fig. 3 that the laser emission spectrum will shift toward short-wavelength side, as the cavity losses are increased by increasing T and/or decreasing T0. This is a common feature for a broad-band quasi-three-level laser. As is known for such lasers, the oscillation, in the absence of an internal wavelength selector, will occur at wavelengths where the net gain reaches its maximum. Depending on the specific absorption and emission cross section spectra for a given laser crystal, the net gain is determined by the fraction of excited active ions (β), which in turn is proportional to the cavity losses. In general, the net gain maximum tends to shift to short-wavelength side with the amount of β being increased (and hence with the cavity losses increased), as calculated for the Yb:YCOB crystal [19

19. A. Aron, G. Aka, B. Viana, A. Kahn-Harari, D. Vivien, F. Druon, F. Balembois, P. Georges, A. Brun, N. Lenain, and M. Jacquet, “Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material,” Opt. Mater. 16(1-2), 181–188 (2001). [CrossRef]

]. This explains the behavior of oscillation wavelength shifting in connection with the change in T and/or T0, observed with the Yb:YCOB laser in the current experiment.

As usual, the pulse repetition frequency (PRF) measured in passively Q-switched operation of the Yb:YCOB laser increased with pump power. Figure 4
Fig. 4 Pulse repetition frequency as a function of Pabs, measured under different Q-switching conditions for the X-cut crystal (a) and for the Y-cut crystal (b).
depicts the variations of PRF with Pabs over the entire operational range, measured under different Q-switching conditions. One sees that the PRF would be greatly reduced with increasing T and decreasing T0. For the X-cut crystal, the maximum PRF measured at Pabs = 7.8 W was 19.0 kHz (T = 10%, T0 = 97.5%), 8.5 kHz (T = 20%, T0 = 94.4%), and 4.5 kHz (T = 40%, T0 = 93.7%); for the Y-cut crystal, it was 16.7 kHz (T = 10%, T0 = 97.5%), and 6.7 kHz (T = 20%, T0 = 94.4%), measured at Pabs = 7.5 W.

The energy contained in a single laser pulse can be determined from the measured output power and the corresponding PRF. Figure 5
Fig. 5 Pulse energy versus Pabs, generated under different Q-switching conditions for the X-cut crystal (a) and for the Y-cut crystal (b).
illustrates the variation of pulse energy with Pabs for different Q-switching conditions. In the case of T = 10%, T0 = 97.5%, the pulse energy generated with the X- and Y-cut crystals was 264 and 240 μJ (maximum), respectively. Under Q-switching conditions of T = 20%, T0 = 94.4%, the pulse energy produced was 422 (X-cut) and 410 μJ (Y-cut). While in Q-switched operation achieved with the X-cut crystal under conditions of T = 40%, T0 = 93.7%, a pulse energy as high as 476 μJ was generated.

Unlike the pulse energy that varied to some extent with pump power, the pulse duration was found to be independent of pump power, it depended only on the T and T0 used when the cavity length remained unchanged. Illustrated in Fig. 6
Fig. 6 Typical profiles of the laser pulses generated under different Q-switching conditions with the X-cut crystal (a) and with the Y-cut crystal (b).
are typical profiles of the laser pulses generated under different conditions of T and T0, measured at an intermediate pump level of Pabs = 4.78 W for the X-cut crystal (a) and Pabs = 4.71 W for the Y-cut crystal (b). In the case of T = 10%, T0 = 97.5%, the laser pulses generated with the X- and Y-cut crystals were respectively 26.2 and 23.5 ns in duration. The laser pulse duration was reduced to 9.3 ns in the operation with the X-cut crystal under conditions of T = 40%, T0 = 93.7%; while with the Y-cut crystal under conditions of T = 20%, T0 = 94.4%, the pulse duration was measured to be 9.5 ns.

Given the pulse energy (Ep) and duration (tp), one can estimate the peak power (Pp) of the laser pulse by Pp = Ep/tp. The peak power reached with the X-cut crystal, under conditions of T = 40% and T0 = 93.7%, amounted to 51.2 kW; with the Y-cut crystal, the peak power achieved was 43.2 kW under Q-switching conditions of T = 20% and T0 = 94.4%.

In a previously reported Yb:YCOB laser passively Q-switched with InGaAs quantum wells acting as saturable absorber, the pulse energy generated was 165 μJ, while the pulse duration was 100 ns [5

5. H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt. 46(12), 2292–2296 (2007). [CrossRef] [PubMed]

]. In terms of average output power, pulse energy, duration, and peak power, the passive Q-switching laser performance of Yb:YCOB demonstrated in the current experiment represents a significant improvement. It is also interesting to note that the Q-switched operation achieved with the InGaAs quantum wells occurred in a range around the center wavelength of 1086 nm [5

5. H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt. 46(12), 2292–2296 (2007). [CrossRef] [PubMed]

], whereas the emission spectra measured for the present Q-switched Yb:YCOB laser fell in the range of 1025−1042 nm. Clearly, they correspond to different emission bands in the emission spectrum of the Yb:YCOB crystal [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

], which originate from different transitions between Stark levels.

Tables 1

Table 1. Parameters Characterizing the Passively Q-switched X-cut Yb:YCOB Laser

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and 2

Table 2. Parameters Characterizing the Passively Q-switched Y-cut Yb:YCOB Laser

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summarize the primary parameters characterizing the passive Q-switching laser performance of the X- and Y-cut Yb:YCOB crystals demonstrated in this experiment, in which the additional symbols are defined as follows: Pavr, maximum average output power; ηopt, optical-to-optical efficiency; ηs, slope efficiency; and λc, center oscillation wavelength.

The performance of a passively Q-switched laser can be predicted theoretically on the basis of rate equations. There have been many analytical or numerical models for this purpose, most of which were developed in the past two decades [27

27. J. J. Degnan, “Theory of the optimally coupled Q-switched laser,” IEEE J. Quantum Electron. 25(2), 214–220 (1989). [CrossRef]

33

33. X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express 13(19), 7708–7719 (2005). [CrossRef] [PubMed]

]. These models turn out to be very helpful, not only in understanding the output characteristics of the passively Q-switched laser, but also in providing a useful guide to optimizing such type of lasers. In what follows, we shall carry out some theoretical calculations for the passively Q-switched Yb:YCOB laser.

We first calculate the laser pulse energy, with the help of the analytical model developed by Chen et al [30

30. Y. F. Chen, Y. P. Lan, and H. L. Chang, “Analytical model for design criteria of passively Q-switched lasers,” IEEE J. Quantum Electron. 37(3), 462–468 (2001). [CrossRef]

]. In this model, two parameters, α and β, are defined as follows: α = (1/γ)(σgs/σ)(A/As), and β = σes/σgs. In these definitions γ is the inversion reduction factor; σ is the stimulated emission cross section of the gain medium; σgs and σes are respectively the ground-state and excited-state absorption cross sections of the saturable absorber; A and As are the effective mode area in the gain medium and in the saturable absorber. For the current Yb:YCOB/Cr4+:YAG Q-switched laser, γ = 0.91; σ = 0.45 × 10−20 cm2; σgs = 4.3 × 10−18 cm2 [33

33. X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express 13(19), 7708–7719 (2005). [CrossRef] [PubMed]

]; σes = 0.82 × 10−18 cm2 [33

33. X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express 13(19), 7708–7719 (2005). [CrossRef] [PubMed]

]; and A/As = 0.8, so we have α = 840, β = 0.19. It is worth noting that the amount of α for the Yb:YCOB laser is very much greater than that for a typical Nd laser such as Nd:YAG or Nd:YVO4. Due to this extremely large α, the upper bound (T0)upper and the lower bound (R)lower simply reduce to (T0)upper = 1 and (R)lower = 0, that is, there is essentially no limit to either T0 or R, and the second threshold condition can always be met by the Yb:YCOB laser. Thus the expression for the pulse energy, given by (26) in [30

30. Y. F. Chen, Y. P. Lan, and H. L. Chang, “Analytical model for design criteria of passively Q-switched lasers,” IEEE J. Quantum Electron. 37(3), 462–468 (2001). [CrossRef]

], can be written as E = (/σ)(A/2γ)f(α,β)ξ(R,T0), where ξ(R,T0) is given by ξ(R,T0) = 2(1−β)(lnR)(lnT0)(1−T0η)(L−lnR−2βlnT0)−1, the output coupler reflectivity R = 1−T, and L represents the round-trip dissipative losses. The f(α,β) and η appearing above are defined by (27) and (28) in [30

30. Y. F. Chen, Y. P. Lan, and H. L. Chang, “Analytical model for design criteria of passively Q-switched lasers,” IEEE J. Quantum Electron. 37(3), 462–468 (2001). [CrossRef]

]. For α = 840, β = 0.19, we get f(α,β) = 1.36. If we take L = 0.02, A = 1.77 × 10−4 cm2 (effective laser beam radius of 75 μm), and = 1.93 × 10−19 J (oscillation wavelength of 1030 nm), the laser pulse energy can be simply calculated for different operational conditions. The results of calculation are listed in Table 3

Table 3. Analytical and Numerical Calculations of the Pulse Energy and Duration for the Yb:YCOB Laser

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.

Comparing the calculated laser pulse energies with the experimental results listed in Tables 1 and 2, one sees that this analytical model provides a very satisfying prediction for the pulse energy generated under conditions of T = 20%, T0 = 94.4% or T = 40%, T0 = 93.7%. For the case of T = 10%, T0 = 97.5%, however, the expected pulse energy, 173 μJ, proves to be substantially lower than that measured experimentally. This discrepancy is assumed to be due to the nominal amount for T0 (97.5%), which might be greater than its real value. As presented in Table 3, the calculated energy for T = 10%, T0 = 96.5%, 246 μJ, agrees very well with the experimental results given in Tables 1 and 2.

In addition to σgs, σes, σ, γ, A/As, and L, whose values were given above, the other parameters needed in the numerical calculation include (using the same symbols as in [33

33. X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express 13(19), 7708–7719 (2005). [CrossRef] [PubMed]

]):ωL = 70 μm, ωp = 100 μm, l = 2.88 mm, n0 = 8.8 × 1020 cm−3, na0 = fan0 = 0.36 × 1020 cm−3, and tr = 0.20 ns. The results obtained from this numerical calculation for the pulse energy and duration are also listed in Table 3. By a comparison with the measured results given in Tables 1 and 2, one sees that the numerical calculation gives a fairly close expectation for the pulse energy and duration, except that the calculated energy for the case of T = 10%, T0 = 97.5% is again much lower than the measured result. The possible reason for this is just as mentioned in the analytical calculation.

It is instructive to make a direct comparison of Yb:YCOB with other Yb crystals in passive Q-switching laser performance. Table 4

Table 4. Comparison of Passive Q-switching Laser Performance Achieved with Various Yb crystals

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summarizes the pulse energy, duration, and peak power, obtained in Cr4+:YAG passively Q-switched laser operations with various Yb crystals, which were achieved with similar plano-concave resonators under similar pumping conditions. In these studies, the cavity lengths in different experiments were in a range of 22−40 mm, while the laser crystals utilized were 2−4 mm in thickness. The Q-switching operational conditions (T and T0) are also listed for each crystal. These data are cited from the following references: Yb:YAB [34

34. J. Liu, Y. Wan, X. Tian, Z. Zhou, W. Han, J. Li, H. Zhang, and J. Wang, “Compact diode-pumped Yb:YAl3(BO3)4 laser generating 14.0 W of continuous-wave and 8.5 W of pulsed output powers,” Appl. Phys. B (2013), doi:. [CrossRef]

], Yb:GdAB [15

15. A. Brenier, C. Tu, Z. Zhu, and J. Li, “Dual-polarization and dual-wavelength diode-pumped laser operation from a birefringent Yb3+-doped GdAl3(BO3)4 nonlinear crystal,” Appl. Phys. B 89(2-3), 323–328 (2007). [CrossRef]

], Yb:CYB [35

35. A. Brenier, C. Tu, Y. Wang, Z. You, Z. Zhu, and J. Li, “Diode-pumped laser operation of Yb3+-doped Y2Ca3B4O12 crystal,” J. Appl. Phys. 104(1), 013102 (2008). [CrossRef]

], Yb:KLuW [36

36. J. Liu, V. Petrov, H. Zhang, and J. Wang, “Power scaling of a continuous-wave and passively Q-switched Yb:KLu(WO4)2 laser end-pumped by a high-power diode,” Appl. Phys. B 88(4), 527–530 (2007). [CrossRef]

], Yb:NaGdW [16

16. J. Liu, V. Petrov, H. Zhang, J. Wang, and M. Jiang, “Efficient passively Q-switched laser operation of Yb in the disordered NaGd(WO4)2 crystal host,” Opt. Lett. 32(12), 1728–1730 (2007). [CrossRef] [PubMed]

], Yb:NaYW [17

17. J. Liu, H. Zhang, J. Wang, and V. Petrov, “Continuous-wave and Q-switched laser operation of Yb:NaY(WO4) 2 crystal,” Opt. Express 15(20), 12900–12904 (2007). [CrossRef] [PubMed]

], Yb:CNGG and Yb:CLNGG [18

18. J. Liu, Y. Wan, Z. Zhou, X. Tian, W. Han, and H. Zhang, “Comparative study on the laser performance of two Yb doped disordered garnet crystals: Yb:CNGG and Yb:CLNGG,” Appl. Phys. B 109(2), 183–188 (2012). [CrossRef]

], Yb:LuGG [25

25. J. Liu, X. Tian, Z. Zhou, K. Wu, W. Han, and H. Zhang, “Efficient laser operation of Yb:Lu3Ga5O12 garnet crystal,” Opt. Lett. 37(12), 2388–2390 (2012). [CrossRef] [PubMed]

], and Yb:YGG [26

26. J. Liu, X. Tian, K. Wu, Q. Dai, W. Han, and H. Zhang, “Highly efficient Q-switched laser operation of Yb:Y3Ga5O12 garnet crystal,” Opt. Express 21(3), 2624–2631 (2013). [CrossRef] [PubMed]

]. In addition to laser parameters, the stimulated emission cross section (σem), fluorescence lifetime (τf), and thermal conductivity (κc), all of which are important for passive Q-switching laser operation, are also listed in Table 4 for each crystal if available, the values presented here are for room-temperature. One can clearly see that the laser pulse energy produced with Yb:YCOB is considerably higher than generated with others except for Yb:GdCOB, an isomorphic crystal belonging to the same oxyborates family. In fact, the two Yb:oxyborates are very similar in spectroscopic properties [8

8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

,19

19. A. Aron, G. Aka, B. Viana, A. Kahn-Harari, D. Vivien, F. Druon, F. Balembois, P. Georges, A. Brun, N. Lenain, and M. Jacquet, “Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material,” Opt. Mater. 16(1-2), 181–188 (2001). [CrossRef]

,37

37. F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B 16(1), 164–172 (1999). [CrossRef]

]. Possessing a still longer fluorescence lifetime (2.5 ms [37

37. F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B 16(1), 164–172 (1999). [CrossRef]

]), the Yb:GdCOB seems to be slightly more advantageous in generating Q-switched laser pulses. However, Yb:YCOB is of greater capability to accommodate more Yb ions while maintaining high crystal quality, which is due to the closer ionic radii of Yb and Y. According to our experimental results, the maximum output power, generated under the same Q-switching operational conditions of T = 20%, T0 = 94.4% with a 2 mm thick Y-cut Yb:GdCOB crystal, amounted only to 1.05 W, despite the very close pulse energy obtained.

4. Conclusion

In summary, the passive Q-switching laser performance of the Yb:YCOB has been studied with crystal samples cut along the principal optical axes, employing different Cr4+:YAG saturable absorbers. Highly efficient Q-switched laser operation was realized by use of the X-cut crystal, with a Cr4+:YAG saturable absorber of T0 = 97.5% and an output coupler of T = 10%, generating an output power of 5.02 W at a pulse repetition rate of 19.0 kHz, with optical-to-optical and slope efficiencies determined to be 82% and 64%, respectively. While in the pulsed operation achieved with the X-cut crystal under conditions of T = 40% and T0 = 93.7%, the output power reached 2.14 W at a pulse repetition rate of 4.5 kHz, with a slope efficiency of 65%, the resulting laser pulse was 9.3 ns in duration, with energy as high as 476 μJ and peak power amounting to 51.2 kW. It turns out that the passive Q-switching laser performance of Yb:YCOB is much superior to most of other Yb crystals which are available at present, revealing its great potential in developing high-energy compact, miniature, or microchip pulsed laser devices.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grants 60978023 and 11144007).

References and links

1.

D. A. Hammons, J. M. Eichenholz, Q. Ye, B. H. T. Chai, L. Shah, R. E. Peale, M. Richardson, and H. Qiu, “Laser action in Yb3+:YCOB (Yb3+:YCa4O(BO3)3),” Opt. Commun. 156(4-6), 327–330 (1998). [CrossRef]

2.

H. Zhang, X. Meng, P. Wang, L. Zhu, X. Liu, R. Cheng, J. Dawes, P. Dekker, S. Zhang, and L. Sun, “Slope efficiency of up to 73% for Yb:Ca4YO(BO3)3 crystal laser pumped by a laser diode,” Appl. Phys. B 68(6), 1147–1149 (1999). [CrossRef]

3.

F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B 16(1), 164–172 (1999). [CrossRef]

4.

F. Augé, F. Balembois, P. Georges, A. Brun, F. Mougel, G. Aka, A. Kahn-Harari, and D. Vivien, “Efficient and tunable continuous-wave diode-pumped Yb3+:Ca4GdO(BO3)3 laser,” Appl. Opt. 38(6), 976–979 (1999). [CrossRef] [PubMed]

5.

H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt. 46(12), 2292–2296 (2007). [CrossRef] [PubMed]

6.

J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B 91(2), 329–332 (2008). [CrossRef]

7.

J. Liu, H. Zhang, J. Wang, and V. Petrov, “Output-coupling-dependent polarization state of a continuous-wave Yb:YCa4O(BO3)3 laser,” Opt. Lett. 32(20), 2909–2911 (2007). [CrossRef] [PubMed]

8.

C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B 26(7), 1310–1314 (2009). [CrossRef]

9.

O. H. Heckl, C. Kränkel, C. R. E. Baer, C. J. Saraceno, T. Südmeyer, K. Petermann, G. Huber, and U. Keller, “Continuous-wave and modelocked Yb:YCOB thin disk laser: first demonstration and future prospects,” Opt. Express 18(18), 19201–19208 (2010). [CrossRef] [PubMed]

10.

G. J. Valentine, A. J. Kemp, D. J. L. Birkin, D. Burns, F. Balembois, P. Georges, H. Bernas, A. Aron, G. Aka, W. Sibbett, A. Brun, M. D. Dawson, and E. Bente, “Femtosecond Yb:YCOB laser pumped by narrow-stripe laser diode and passively modelocked using ion implanted saturable-absorber mirror,” Electron. Lett. 36(19), 1621–1623 (2000). [CrossRef]

11.

V. Petrov, X. Mateos, A. Schmidt, S. Rivier, U. Griebner, H. Zhang, J. Wang, J. Li, and J. Liu, “Passive mode-locking of acentric Yb-doped borate crystals,” Laser Phys. 20(5), 1085–1090 (2010). [CrossRef]

12.

A. Yoshida, A. Schmidt, H. Zhang, J. Wang, J. Liu, C. Fiebig, K. Paschke, G. Erbert, V. Petrov, and U. Griebner, “42-fs diode-pumped Yb:Ca4YO(BO3)3 oscillator,” Opt. Express 18(23), 24325–24330 (2010). [CrossRef] [PubMed]

13.

A. Yoshida, A. Schmidt, V. Petrov, C. Fiebig, G. Erbert, J. Liu, H. Zhang, J. Wang, and U. Griebner, “Diode-pumped mode-locked Yb:YCOB laser generating 35 fs pulses,” Opt. Lett. 36(22), 4425–4427 (2011). [CrossRef] [PubMed]

14.

W. Koechner, Solid-State Laser Engineering (Springer, 2006).

15.

A. Brenier, C. Tu, Z. Zhu, and J. Li, “Dual-polarization and dual-wavelength diode-pumped laser operation from a birefringent Yb3+-doped GdAl3(BO3)4 nonlinear crystal,” Appl. Phys. B 89(2-3), 323–328 (2007). [CrossRef]

16.

J. Liu, V. Petrov, H. Zhang, J. Wang, and M. Jiang, “Efficient passively Q-switched laser operation of Yb in the disordered NaGd(WO4)2 crystal host,” Opt. Lett. 32(12), 1728–1730 (2007). [CrossRef] [PubMed]

17.

J. Liu, H. Zhang, J. Wang, and V. Petrov, “Continuous-wave and Q-switched laser operation of Yb:NaY(WO4) 2 crystal,” Opt. Express 15(20), 12900–12904 (2007). [CrossRef] [PubMed]

18.

J. Liu, Y. Wan, Z. Zhou, X. Tian, W. Han, and H. Zhang, “Comparative study on the laser performance of two Yb doped disordered garnet crystals: Yb:CNGG and Yb:CLNGG,” Appl. Phys. B 109(2), 183–188 (2012). [CrossRef]

19.

A. Aron, G. Aka, B. Viana, A. Kahn-Harari, D. Vivien, F. Druon, F. Balembois, P. Georges, A. Brun, N. Lenain, and M. Jacquet, “Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material,” Opt. Mater. 16(1-2), 181–188 (2001). [CrossRef]

20.

A. E. Siegman, Lasers (Mill Valley, California: University Science, 1986).

21.

J. Dong, M. Bass, Y. Mao, P. Deng, and F. Gan, “Dependence of the Yb3+ emission cross section and lifetime on temperature and concentration in yttrium aluminum garnet,” J. Opt. Soc. Am. B 20(9), 1975–1979 (2003). [CrossRef]

22.

A. V. Kir’yanov and J. C. Bermudez , “Anisotropy of refractive-index nonlinear change in Cr4+: YAG at cw resonant excitation: modeling,” J. Opt. Soc. Am. B 20(12), 2454–2469 (2003). [CrossRef]

23.

Y. Kalisky, “Cr4+-doped crystals: their use as lasers and passive Q-switches,” Prog. Quantum Electron. 28(5), 249–303 (2004). [CrossRef]

24.

O. Svelto, Principles of Lasers (Springer, 2010).

25.

J. Liu, X. Tian, Z. Zhou, K. Wu, W. Han, and H. Zhang, “Efficient laser operation of Yb:Lu3Ga5O12 garnet crystal,” Opt. Lett. 37(12), 2388–2390 (2012). [CrossRef] [PubMed]

26.

J. Liu, X. Tian, K. Wu, Q. Dai, W. Han, and H. Zhang, “Highly efficient Q-switched laser operation of Yb:Y3Ga5O12 garnet crystal,” Opt. Express 21(3), 2624–2631 (2013). [CrossRef] [PubMed]

27.

J. J. Degnan, “Theory of the optimally coupled Q-switched laser,” IEEE J. Quantum Electron. 25(2), 214–220 (1989). [CrossRef]

28.

J. J. Degnan, “Optimization of passively Q-switched lasers,” IEEE J. Quantum Electron. 31(11), 1890–1901 (1995). [CrossRef]

29.

G. Xiao and M. Bass, “A generalized model for passively Q-switched lasers including excited state absorption in the saturable absorber,” IEEE J. Quantum Electron. 33(1), 41–44 (1997). [CrossRef]

30.

Y. F. Chen, Y. P. Lan, and H. L. Chang, “Analytical model for design criteria of passively Q-switched lasers,” IEEE J. Quantum Electron. 37(3), 462–468 (2001). [CrossRef]

31.

F. D. Patel and R. J. Beach, “New formalism for the analysis of passively Q-switched laser systems,” IEEE J. Quantum Electron. 37(5), 707–715 (2001). [CrossRef]

32.

J. Dong, “Numerical modeling of CW-pumped repetitively passively Q-switched Yb:YAG lasers with Cr:YAG as saturable absorber,” Opt. Commun. 226(1-6), 337–344 (2003). [CrossRef]

33.

X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express 13(19), 7708–7719 (2005). [CrossRef] [PubMed]

34.

J. Liu, Y. Wan, X. Tian, Z. Zhou, W. Han, J. Li, H. Zhang, and J. Wang, “Compact diode-pumped Yb:YAl3(BO3)4 laser generating 14.0 W of continuous-wave and 8.5 W of pulsed output powers,” Appl. Phys. B (2013), doi:. [CrossRef]

35.

A. Brenier, C. Tu, Y. Wang, Z. You, Z. Zhu, and J. Li, “Diode-pumped laser operation of Yb3+-doped Y2Ca3B4O12 crystal,” J. Appl. Phys. 104(1), 013102 (2008). [CrossRef]

36.

J. Liu, V. Petrov, H. Zhang, and J. Wang, “Power scaling of a continuous-wave and passively Q-switched Yb:KLu(WO4)2 laser end-pumped by a high-power diode,” Appl. Phys. B 88(4), 527–530 (2007). [CrossRef]

37.

F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B 16(1), 164–172 (1999). [CrossRef]

OCIS Codes
(140.3540) Lasers and laser optics : Lasers, Q-switched
(140.3580) Lasers and laser optics : Lasers, solid-state
(140.3615) Lasers and laser optics : Lasers, ytterbium

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: February 20, 2013
Revised Manuscript: April 4, 2013
Manuscript Accepted: April 5, 2013
Published: April 9, 2013

Citation
Junhai Liu, Qibiao Dai, Yong Wan, Wenjuan Han, and Xueping Tian, "The potential of Yb:YCa4O(BO3)3 crystal in generating high-energy laser pulses," Opt. Express 21, 9365-9376 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-8-9365


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References

  1. D. A. Hammons, J. M. Eichenholz, Q. Ye, B. H. T. Chai, L. Shah, R. E. Peale, M. Richardson, and H. Qiu, “Laser action in Yb3+:YCOB (Yb3+:YCa4O(BO3)3),” Opt. Commun.156(4-6), 327–330 (1998). [CrossRef]
  2. H. Zhang, X. Meng, P. Wang, L. Zhu, X. Liu, R. Cheng, J. Dawes, P. Dekker, S. Zhang, and L. Sun, “Slope efficiency of up to 73% for Yb:Ca4YO(BO3)3 crystal laser pumped by a laser diode,” Appl. Phys. B68(6), 1147–1149 (1999). [CrossRef]
  3. F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B16(1), 164–172 (1999). [CrossRef]
  4. F. Augé, F. Balembois, P. Georges, A. Brun, F. Mougel, G. Aka, A. Kahn-Harari, and D. Vivien, “Efficient and tunable continuous-wave diode-pumped Yb3+:Ca4GdO(BO3)3 laser,” Appl. Opt.38(6), 976–979 (1999). [CrossRef] [PubMed]
  5. H. C. Liang, J. Y. Huang, K. W. Su, H. C. Lai, Y. F. Chen, K. F. Huang, H. J. Zhang, J. Y. Wang, and M. H. Jiang, “Passively Q-switched Yb3+:YCa4O(BO3)3 laser with InGaAs quantum wells as saturable absorbers,” Appl. Opt.46(12), 2292–2296 (2007). [CrossRef] [PubMed]
  6. J. Liu, W. Han, H. Zhang, J. Wang, and V. Petrov, “Comparison of laser performance of Yb:YCa4O(BO3)3 crystals cut along the principal optical axes,” Appl. Phys. B91(2), 329–332 (2008). [CrossRef]
  7. J. Liu, H. Zhang, J. Wang, and V. Petrov, “Output-coupling-dependent polarization state of a continuous-wave Yb:YCa4O(BO3)3 laser,” Opt. Lett.32(20), 2909–2911 (2007). [CrossRef] [PubMed]
  8. C. Kränkel, R. Peters, K. Petermann, P. Loiseau, G. Aka, and G. Huber, “Efficient continuous-wave thin disk laser operation of Yb:Ca4YO(BO3)3 in E//Z and E//X orientations with 26 W output power,” J. Opt. Soc. Am. B26(7), 1310–1314 (2009). [CrossRef]
  9. O. H. Heckl, C. Kränkel, C. R. E. Baer, C. J. Saraceno, T. Südmeyer, K. Petermann, G. Huber, and U. Keller, “Continuous-wave and modelocked Yb:YCOB thin disk laser: first demonstration and future prospects,” Opt. Express18(18), 19201–19208 (2010). [CrossRef] [PubMed]
  10. G. J. Valentine, A. J. Kemp, D. J. L. Birkin, D. Burns, F. Balembois, P. Georges, H. Bernas, A. Aron, G. Aka, W. Sibbett, A. Brun, M. D. Dawson, and E. Bente, “Femtosecond Yb:YCOB laser pumped by narrow-stripe laser diode and passively modelocked using ion implanted saturable-absorber mirror,” Electron. Lett.36(19), 1621–1623 (2000). [CrossRef]
  11. V. Petrov, X. Mateos, A. Schmidt, S. Rivier, U. Griebner, H. Zhang, J. Wang, J. Li, and J. Liu, “Passive mode-locking of acentric Yb-doped borate crystals,” Laser Phys.20(5), 1085–1090 (2010). [CrossRef]
  12. A. Yoshida, A. Schmidt, H. Zhang, J. Wang, J. Liu, C. Fiebig, K. Paschke, G. Erbert, V. Petrov, and U. Griebner, “42-fs diode-pumped Yb:Ca4YO(BO3)3 oscillator,” Opt. Express18(23), 24325–24330 (2010). [CrossRef] [PubMed]
  13. A. Yoshida, A. Schmidt, V. Petrov, C. Fiebig, G. Erbert, J. Liu, H. Zhang, J. Wang, and U. Griebner, “Diode-pumped mode-locked Yb:YCOB laser generating 35 fs pulses,” Opt. Lett.36(22), 4425–4427 (2011). [CrossRef] [PubMed]
  14. W. Koechner, Solid-State Laser Engineering (Springer, 2006).
  15. A. Brenier, C. Tu, Z. Zhu, and J. Li, “Dual-polarization and dual-wavelength diode-pumped laser operation from a birefringent Yb3+-doped GdAl3(BO3)4 nonlinear crystal,” Appl. Phys. B89(2-3), 323–328 (2007). [CrossRef]
  16. J. Liu, V. Petrov, H. Zhang, J. Wang, and M. Jiang, “Efficient passively Q-switched laser operation of Yb in the disordered NaGd(WO4)2 crystal host,” Opt. Lett.32(12), 1728–1730 (2007). [CrossRef] [PubMed]
  17. J. Liu, H. Zhang, J. Wang, and V. Petrov, “Continuous-wave and Q-switched laser operation of Yb:NaY(WO4) 2 crystal,” Opt. Express15(20), 12900–12904 (2007). [CrossRef] [PubMed]
  18. J. Liu, Y. Wan, Z. Zhou, X. Tian, W. Han, and H. Zhang, “Comparative study on the laser performance of two Yb doped disordered garnet crystals: Yb:CNGG and Yb:CLNGG,” Appl. Phys. B109(2), 183–188 (2012). [CrossRef]
  19. A. Aron, G. Aka, B. Viana, A. Kahn-Harari, D. Vivien, F. Druon, F. Balembois, P. Georges, A. Brun, N. Lenain, and M. Jacquet, “Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material,” Opt. Mater.16(1-2), 181–188 (2001). [CrossRef]
  20. A. E. Siegman, Lasers (Mill Valley, California: University Science, 1986).
  21. J. Dong, M. Bass, Y. Mao, P. Deng, and F. Gan, “Dependence of the Yb3+ emission cross section and lifetime on temperature and concentration in yttrium aluminum garnet,” J. Opt. Soc. Am. B20(9), 1975–1979 (2003). [CrossRef]
  22. A. V. Kir’yanov and J. C. Bermudez , “Anisotropy of refractive-index nonlinear change in Cr4+: YAG at cw resonant excitation: modeling,” J. Opt. Soc. Am. B20(12), 2454–2469 (2003). [CrossRef]
  23. Y. Kalisky, “Cr4+-doped crystals: their use as lasers and passive Q-switches,” Prog. Quantum Electron.28(5), 249–303 (2004). [CrossRef]
  24. O. Svelto, Principles of Lasers (Springer, 2010).
  25. J. Liu, X. Tian, Z. Zhou, K. Wu, W. Han, and H. Zhang, “Efficient laser operation of Yb:Lu3Ga5O12 garnet crystal,” Opt. Lett.37(12), 2388–2390 (2012). [CrossRef] [PubMed]
  26. J. Liu, X. Tian, K. Wu, Q. Dai, W. Han, and H. Zhang, “Highly efficient Q-switched laser operation of Yb:Y3Ga5O12 garnet crystal,” Opt. Express21(3), 2624–2631 (2013). [CrossRef] [PubMed]
  27. J. J. Degnan, “Theory of the optimally coupled Q-switched laser,” IEEE J. Quantum Electron.25(2), 214–220 (1989). [CrossRef]
  28. J. J. Degnan, “Optimization of passively Q-switched lasers,” IEEE J. Quantum Electron.31(11), 1890–1901 (1995). [CrossRef]
  29. G. Xiao and M. Bass, “A generalized model for passively Q-switched lasers including excited state absorption in the saturable absorber,” IEEE J. Quantum Electron.33(1), 41–44 (1997). [CrossRef]
  30. Y. F. Chen, Y. P. Lan, and H. L. Chang, “Analytical model for design criteria of passively Q-switched lasers,” IEEE J. Quantum Electron.37(3), 462–468 (2001). [CrossRef]
  31. F. D. Patel and R. J. Beach, “New formalism for the analysis of passively Q-switched laser systems,” IEEE J. Quantum Electron.37(5), 707–715 (2001). [CrossRef]
  32. J. Dong, “Numerical modeling of CW-pumped repetitively passively Q-switched Yb:YAG lasers with Cr:YAG as saturable absorber,” Opt. Commun.226(1-6), 337–344 (2003). [CrossRef]
  33. X. Zhang, A. Brenier, Q. Wang, Z. Wang, J. Chang, P. Li, S. Zhang, S. Ding, and S. Li, “Passive Q-switching characteristics of Yb3+:Gd3Ga5O12 crystal,” Opt. Express13(19), 7708–7719 (2005). [CrossRef] [PubMed]
  34. J. Liu, Y. Wan, X. Tian, Z. Zhou, W. Han, J. Li, H. Zhang, and J. Wang, “Compact diode-pumped Yb:YAl3(BO3)4 laser generating 14.0 W of continuous-wave and 8.5 W of pulsed output powers,” Appl. Phys. B (2013), doi:. [CrossRef]
  35. A. Brenier, C. Tu, Y. Wang, Z. You, Z. Zhu, and J. Li, “Diode-pumped laser operation of Yb3+-doped Y2Ca3B4O12 crystal,” J. Appl. Phys.104(1), 013102 (2008). [CrossRef]
  36. J. Liu, V. Petrov, H. Zhang, and J. Wang, “Power scaling of a continuous-wave and passively Q-switched Yb:KLu(WO4)2 laser end-pumped by a high-power diode,” Appl. Phys. B88(4), 527–530 (2007). [CrossRef]
  37. F. Mougel, K. Dardenne, G. Aka, A. Kahn-Harari, and D. Vivien, “Ytterbium-doped Ca4GdO(BO3)3: an efficient infrared laser and self-frequency doubling crystal,” J. Opt. Soc. Am. B16(1), 164–172 (1999). [CrossRef]

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