Hybrid Q-switched broadband laser source with low timing jitter

doi:10.1364/OE.20.001202

Hybrid Q-switched broadband laser source with low timing jitter

Farid El Bassri, Florent Doutre, Nicolas Mothe, Lionel Jaffres, Dominique Pagnoux, Vincent Couderc, and Alain Jalocha »View Author Affiliations

Optics Express, Vol. 20, Issue 2, pp. 1202-1212 (2012)
http://dx.doi.org/10.1364/OE.20.001202

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▸ Article Outline
– Abstract
1. Introduction
2. Novel hybrid active/passive Q-switched laser structure
3. Numerical and experimental results
4. Conclusion
– References and links

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Abstract

We present a novel broadband laser source based on a dual cavity in which a subnanosecond passively Q-switched microchip laser is coupled with a long cavity including an acousto-optic modulator (AOM) and a microstructured optical fiber working as a non linear medium. This active-passive Q-switched laser source emits pulses as short as those emitted by the free running microchip laser (~600 ps). The time pulse emission is governed by the AOM allowing tunable repetition rate from 0 to more than 4 kHz with a temporal jitter reduced to less than 50 ns, i.e. a 600-fold reduction compared to that of the free running microchip. Furthermore, thanks to spectral broadening in the microstructured fiber, this source emits a supercontinuum from 700 nm to 1700 nm.

1. Introduction

Number of applications such as accurate range finding, CARS microspectroscopy, imaging or flow cytometry require high peak power optical pulses with duration as short as few hundred of picoseconds, reduced jitter and broadband spectrum [1

P. Thony, P. Labeye, V. Marty, R. Templier, P. Bésesty, and E. Molva, “1 µm single-frequency tunable microchip lasers for range finding,” Conference Paper on Advanced Solid State Lasers (ASSL), Poster Session II, Boston, Massachusetts, USA, (1999).

–4

H. W. Wang, N. Bao, T. L. Le, C. Lu, and J. X. Cheng, “Microfluidic CARS cytometry,” Opt. Express 16(8), 5782–5789 (2008). [CrossRef] [PubMed]

]. Tunability of the repetition rate is also an attractive feature which can be required for these applications. Passively Q-switched microchip (PQSM) lasers with subnanosecond pulse emission can be a suitable solution to obtain such characteristics. These sources are reliable and low cost, generally based on a short cavity including a saturable absorber and an amplifying crystal, longitudinally pumped by a laser diode [5

J. J. Zayhowski and A. Mooradian, “Single-frequency microchip Nd lasers,” Opt. Lett. 14(1), 24–26 (1989). [CrossRef] [PubMed]

D. Nodop, J. Limpert, R. Hohmuth, W. Richter, M. Guina, and A. Tünnermann, “High pulse energy passively quasi-monolithic microchip lasers operating in the sub-100-ps pulse regime,” Opt. Lett. 32(15), 2115–2117 (2007). [CrossRef] [PubMed]

]. When launched in a highly non linear fiber, pulses from a PQSM laser can generate broadband supercontinuum [7

A. Mussot, T. Sylvestre, L. Provino, and H. Maillotte, “Generation of a broadband single-mode supercontinuum in a conventional dispersion-shifted fiber by use of a subnanosecond microchip laser,” Opt. Lett. 28(19), 1820–1822 (2003). [CrossRef] [PubMed]

C. Lesvigne, V. Couderc, A. Tonello, P. Leproux, A. Barthélémy, S. Lacroix, F. Druon, P. Blandin, M. Hanna, and P. Georges, “Visible supercontinuum generation controlled by intermodal four-wave mixing in microstructured fiber,” Opt. Lett. 32(15), 2173–2175 (2007). [CrossRef] [PubMed]

]. However, a large timing jitter of the interpulse period is often measured in that type of laser. Two mains causes can be identified for timing jitter. The first one is that laser oscillation starts from spontaneous emission which is a statistical phenomenon. The second one comes from fluctuations of different parameters such as pump power, cavity loss, and temperature. Many works have been recently carried out to reduce the timing jitter of Q-switched microchip lasers [9

N. D. Lai, M. Brunel, F. Bretenaker, and A. Le Floch, “Stabilization of the repetition rate of passively Q-switched diode pumped solid state lasers,” Appl. Phys. (Berl.) 79(8), 1073–1075 (2001).

–16

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

]. Several techniques are based on the combination of active and passive switching methods. Gain switching is provided by means of two level modulation of the pump power. By slightly modulating this parameter, time stability of 10⁻⁶ can be obtained [9

]. In this case, the modulation frequency must be maintained very close to the laser repetition rate dictated by the passive Q-switching element and the pump power [9

]. More recently, a novel scheme combining gain switching with passive Q-switching of a miniature diode-pumped solid-state laser has been proposed [10

J. B. Khurgin, F. Jin, G. Solyar, C. C. Wang, and S. Trivedi, “Cost-effective low timing jitter passively Q-switched diode-pumped solid-state laser with composite pumping pulses,” Appl. Opt. 41(6), 1095–1097 (2002). [CrossRef] [PubMed]

,11

A. F. Shatalov, “Reduction of the pulse repetition period jitter of a diode pumped passively Q-switched solid state laser,” Radiophys Quantum Electron. 52(4), 305–310 (2009).

]. However, reduction factors of the jitter not better than 10 have been obtained. Furthermore, in all the above devices, the temporal profile of the pump power must be accurately controlled, requiring the use of advanced high-cost electronics. In an alternative technique, the passive saturable absorber of a Q-switched laser is directly bleached by means of an external transverse light pulse provided by a subsidiary laser diode [12

B. Cole, L. Goldberg, C. W. Trussell, A. Hays, B. W. Schilling, and C. McIntosh, “Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber,” Opt. Express 17(3), 1766–1771 (2009). [CrossRef] [PubMed]

]. The bleaching of the saturable absorber causes a rapid decrease of the cavity loss, resulting in a pulse emission with a reduced timing jitter of a factor 12. Significant reduction of timing jitter in a PQSM laser (pulse duration ~200 ps) can also be obtained using self injection seeding [13

A. Steinmetz, D. Nodop, A. Martin, J. Limpert, and A. Tünnermann, “Reduction of timing jitter in passively Q-switched microchip lasers using self-injection seeding,” Opt. Lett. 35(17), 2885–2887 (2010). [CrossRef] [PubMed]

]. A small part of an emitted pulse is delayed into a fiber delay line, and reinjected into the laser cavity just before the next pulse emission. Thus, this backseeded pulse initializes the onset of the following pulse emission, resulting in a jitter stabilization with a factor of 500. However, the repetition rate of the laser must be comprised in a very narrow range, slightly lower than the reciprocal of the propagation time in the fiber. Thus, for a given length of fiber, the repetition rate of the laser must be set consequently and it is no longer tunable. Another solution reported in ref [14

B. Hansson and M. Arvidsson, “Q-switched microchip laser with 65 ps timing jitter,” Electron. Lett. 36(13), 1123–1124 (2000). [CrossRef]

] consists in the association of a LiNbO₃ crystal operating as a Pockels cell and a Cr⁴⁺:YAG saturable absorber. With this scheme, a significant reduction of the timing jitter down to 65 ps has been obtained. The method has also been used for obtaining high-power pulses in a Q-switched Cr⁴⁺, Nd³⁺:YAG laser with reduced jitter by using an acousto-optic modulator in the cavity [15

X. J. Wang and Z. Y. Xu, “Timing jitter and pulse width reduction in a Hybrid Q-switched Cr,Nd:YAG laser,” Chin. Phys. Lett. 23(7), 1800–1802 (2006). [CrossRef]

]. The 268 µs free run jitter of the laser was decreased down to 0.4 µs. However, in both cases, the cavity length is dramatically increased because of the bulky active modulator. As a result, only long duration pulses can be emitted (> 3 ns).

In this paper, we propose a novel scheme of pulse laser source, based on a dual cavity configuration including a subnanosecond PQSM laser. It has been designed in order to preserve the temporal profile of the short pulses from the PQSM laser while drastically minimizing its free run timing jitter and allowing intracavity emission of broadband pulses at a tunable repetition rate. The structure of this source is first described and its operating principle is exposed. Then, its jitter is numerically evaluated and it is compared to experimental values. Finally, the temporal and spectral characteristics of the emitted pulses are reported and discussed.

2. Novel hybrid active/passive Q-switched laser structure

The scheme of the proposed pulse laser source is depicted in Fig. 1 . It consists in a hybrid active/passive Q-switched laser structure with two coupled cavities. The cavity 1 is a short length Nd:YAG microchip laser from Horus Company (Nd:YAG crystal length l = 4 mm), emitting at 1064 nm, passively Q-switched by means of a Cr⁴⁺:YAG saturable absorber crystal (l_as = 2.5 mm). The cavity is formed by two dielectric mirrors M₁ and M₂, with reflectivity of 100% and 60% respectively, at the 1064 nm wavelength. Due to its short cavity length, this laser can emit short duration pulses (~600 ps), which are longitudinally quasi-single mode. The cavity 1 is set in a second long cavity (cavity 2, typical length ~2 m) formed between the common mirror M₁ and an output mirror M₃ and including an active modulator and a non linear element. More precisely, the beam from this PQSM laser is launched into a piece of single mode fiber (L_of ~1 m, NA = 0.2, λ_c = 980 nm) which achieves spatial filtering in order to provide transversal single mode emission, and this fiber is spliced to a fibered acousto-optic modulator (AOM), itself connected to a piece of highly non linear fiber (HNL fiber) which is butt joint to the mirror M₃ (dichroic mirror, with high reflectivity at 1064 nm ~100%).

Fig. 1 Hybrid active/passive Q-switched laser source.

This arrangement is pumped by a continuous laser diode at 808 nm, with a power lower than the cavity 1 laser threshold. When the modulator is on (light deflection), it causes high loss in cavity 2 and no laser emission is observed (Fig. 2a ). When it is switched off (light transmission at time t₁), the internal loss of the cavity 2 suddenly drops from a high to a low value. This turns in abruptly increasing the effective reflectivity of the mirror M₂ of the cavity 1 and a pulse is emitted at 1064 nm as illustrated in Fig. 2b. Because this pulse is entirely built in the cavity 1, the short duration of the free running PQSM laser pulses is preserved. Furthermore, the time emission t₁ coincides with the abrupt drop of the PQSM laser threshold governed by the active modulator, which reduces the pulse creation delay (PCD). Thus, the uncertainty on the emission time is expected to be significantly lower than the timing jitter of the free running PQSM laser. Furthermore, the repetition rate of the source can be tuned by controlling the switching frequency of the modulator.

Fig. 2 Schematic representation of the inversion density in the PQSM laser when pumped at a level lower than cavity 1 laser threshold; (a) high loss in the cavity 2 (no pulse emission), (b) switch to low loss in the cavity 2 at time t₁ resulting in an abrupt drop of the cavity 1 laser threshold (pulse emission at t₁). Hatched regions are the inversion density uncertainty domains where pulse emission starts.

Finally, the HNL fiber in cavity 2 is pumped by the pulses emitted by the PQSM and a broadband supercontinuum is generated and emitted through the dichroic mirror M₃. Let us note that because of the strong depletion of the 1064 nm pulses along the fiber associated to the nonlinear spectral broadening, reinjected light in the cavity 1 after the reflexion on the mirror M₃ is negligible. In case of remaining light at 1064 nm on mirror M₃, which reflexion could initiate the oscillation of a second parasitic additional pulse in the cavity 2, it could be easily removed by switching the modulator on just after the main pulse crossing.

3. Numerical and experimental results

By means of a high speed PIN photodetector connected to a broadband oscilloscope (Tektronix CSA 8000), we first experimentally measured the timing jitter of the pulses emitted by the free running PQSM laser (600 ps duration and 11 kW peak power) when pumped with increasing pump power at 808 nm, i.e. with increasing repetition rates. As expected, the jitter decreases when increasing the pump power due to the increase of the inversion density slope versus time. This results in a decrease of the time jitter from 30 µs at 2 kHz to about 7 µs over 7 kHz (Fig. 3 ). Thus, the relative jitter remains close to 5-6.10⁻² over the considered range of repetition rates. We also modeled this free running PQSM laser by means of the coupled rate equations Eq. (1) to Eq. (3) in which the Cr⁴⁺:YAG saturable absorber was described by a four level system [16

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

,17

J. J. Zayhowski, “Passively Q-switched microchip lasers,” in Solid-state lasers and applications, ed. A. Sennaroglu, (CRC/Taylor&Francis Ed. 2007).

Fig. 3 Experimental (solid line) and numerical (dashed line) jitter of the PQSM laser, versus repetition rate.

\frac{d φ}{d t} = \frac{φ}{t_{r}} (2 σ N l - 2 σ_{f} N_{f} l_{s a} - 2 σ_{e} . N_{e} . l_{s a} - \ln (\frac{1}{R}) - L) + φ_{s p}

(1)

\frac{d N}{d t} = W_{p} - 2 c σ N φ - \frac{N}{τ}

(2)

\frac{d N_{f}}{d t} = \frac{N_{e}}{τ_{s a}} - 2 c σ_{f} . N_{f} . φ

(3)

The parameters involved in the Eq. (1) to Eq. (3) equations system are defined and reported in Table 1 .

Table 1 Parameters of the Nd:YAG/Cr⁴⁺:YAG passively Q-switched microchip laser

Parameter	Name	Value
velocity of light in the vacuum	c	3.10⁸ m/s
length of the gain medium	L	4 mm
length of the saturable absorber	l_sa	2,5 mm
reflectivity of the output mirror M1 and M2	R	60%
stimulated emission cross section	Σ	6,6.10⁻²³ m²
absorber ground state cross section	σ_f	4,3.10⁻²² m²
absorber excited state cross section	σ_e	8,2.10⁻²³ m²
lifetime of the excited state of the gain medium	Τ	230 μs
lifetime of the excited state of the saturable absorber	τ_sa	4 μs
non saturable round trip dissipative optical loss in the cavity	L	2%
pumping rate	W_p	$\frac{P_{p} (1 - \exp (- 2 α l)) λ_{p}}{h c A_{p} l}$
pump wavelength	λ_p	808 nm
absorption of the pump photons	α	600 m⁻¹
effective area of the pumping beam	A_p	2.5 10⁻⁸ m²
pump power	P_p	from 0 to 5 W
round trip time in the cavity	t_r	2n_YAG (l + l_as)/c
YAG index @ pump wavelength	n_YAG	1.82
intracavity photon density	φ	variable parameters along time
spontaneous emission [17 J. J. Zayhowski, “Passively Q-switched microchip lasers,” in Solid-state lasers and applications, ed. A. Sennaroglu, (CRC/Taylor&Francis Ed. 2007). ]	_{$φ_{s p} = \frac{σ N}{A_{p} . t_{r}}$}
instantaneous population inversion density	N
ground state absorber population density	N_f
excited state absorber population density	N_e

As stated above, the timing jitter in actual passively Q-switched lasers is mainly due to pump power fluctuations, and thermal and mechanical drifts in the cavity. In order to simulate the PQSM laser suffering from timing jitter, we arbitrarily choose to express all the jitter causes by only random fluctuations of the pump power, inducing fluctuations of the pumping rate W_p around its mean value. Thus the constant value W_p in Eq. (2) is replaced by a random value set W’_p between (1-η)W_p and (1+η)W_p, where η is the fluctuation rate of W_p. In the calculations, the random changes of the pump power are supposed to occur at random moments, separated by about few tens µs. The statistics of the fluctuations of W_p is set in order to correspond to a Gaussian white noise over a few kHz bandwidth added to W_p, as it is the case in actual laser diode sources [18

C. C. Harb, T. C. Ralph, E. H. Huntington, D. E. McClelland, H.-A. Bachor, and I. Freitag, “Intensity noise dependence of Nd-YAG lasers on their diode-laser pump source,” J. Opt. Soc. Am. B 14(11), 2936–2945 (1997). [CrossRef]

]. The 30 µs jitter experimentally measured at the 2 kHz repetition rate was numerically found for a value of η = 3%. This fluctuation rate being maintained for higher pump powers, we have computed the corresponding jitter for higher repetition rates (Fig. 3). The numerical results are in very close agreement with the experimental measurements, confirming the validity of our model.

We now consider the hybrid active-passive laser source depicted in Fig. 1. The insertion loss of the AOM in the cavity 2 is 6 dB and 0.7 dB for the on/off positions respectively, and the rise time and fall time are ~5 ns. The HNL fiber is 2 m long. Taking into account the additional loss in the fibers and at the splices, the global loss over one round trip in the cavity 2 at 1064 nm is evaluated to be 2.8 dB and 13.4 dB respectively. The corresponding effective reflectivity of mirror M₂ (which was 60% in the isolated PQSM laser) is now respectively R_2low = 62% and R_2high = 81%. The pump power is set to a value slightly lower than the threshold required for pulse emission when the AOM is on. By switching the AOM, the effective reflectivity of mirror M₂ is then periodically switched from R_2low to R_2high during time intervals t_l and t_h respectively. Obviously, to ensure single pulse emission during t_h, this time interval must be shorter than the interpulse duration in the hybrid source when the AOM is maintained off. In these conditions, we measured the timing jitter and the PCD for different repetition rates, from 100 Hz to 4 kHz, governed by the AOM (Fig. 4 ). The timing jitter, which was defined as the largest temporal delay between all the laser shots recorded over ~5 s, was measured with the fast Tektronix CSA 8000 oscilloscope (Fig. 5a ). Both the jitter and the PCD are increased as the repetition rate is increased. However, the jitter does not exceed ~80 ns at 4 kHz (i.e. a 200-fold reduction compared to that of the free running PQSM laser) and it remains close to 50 ns below 3 kHz (corresponding to a 400 to 600-fold reduction). The relative jitter was found to remain below 3.10⁻⁴ whatever the repetition rate, the lowest value reaching 5.10⁻⁶ at low repetition rate (100 Hz). We also measured histograms of the jitter for a large number of successive pulses, in order to evaluate the dispersion of these jitters around the zero value. Figure 5b is a typical example of such an histogram measured for ~15 10³ successive pulses at 3 kHz repetition rate (measurement duration ~5 s). It shows that a large number of pulses suffer from a jitter significantly lower than the timing jitter considered in Fig. 4. (FWHM = 18 ns, to be compared to the 50 ns value plotted in Fig. 4). The laser PCD of the hybrid laser was found to be lower than 900 ns. Let us note that because of the limited pump power set below the microchip laser threshold, the output available repetition rate cannot exceed 4 kHz. This limitation can be overcome by reducing the time required for obtaining the necessary population inversion. This technique consists in synchronously switching the pump power with the AOM as already demonstrated in [10

,11

A. F. Shatalov, “Reduction of the pulse repetition period jitter of a diode pumped passively Q-switched solid state laser,” Radiophys Quantum Electron. 52(4), 305–310 (2009).

Fig. 4 Experimental (solid line) and computed (dashed line) timing jitter and pulse creation delay (dotted line) in the hybrid source depicted in Fig. 1, versus repetition rate.

Fig. 5 Example of jitter measurements at repetition rate = 3kHz: (a) superimposed pulses recorded over ~5 s for determining the maximum jitter considered in Fig. 4; (b) histogram of the jitter for 15 10³ successive pulses showing that the FWHM jitter (~18ns) is significantly lower than the considered maximum value (~50 ns).

To model this source, we considered that it was equivalent to the only PQSM laser in which the reflectivity of the output mirror M2 is alternately switched between a low (62%) and a high (81%) value, within few nanoseconds corresponding to the typical rise and fall times of the AOM. Thus, we adapted the set of Eqs. (1) to (3), and we used low mean pump power (P = 1 W) with the same fluctuations of ±3% as for the free running PQSM laser. The results are reported in Fig. 4. They are in very good agreement with experimental measurements at high repetition rates whereas the jitter predicted below 3.5 kHz (20-30 ns) is found to be somewhat lower than the measured one (45-50 ns). This slight discrepancy can be due to some underestimation of the equivalent pump power fluctuations representing the overall jitter causes, at low repetition rates.

The last part of the study concerns the temporal and spectral characterization of the pulses emitted by the source. Their temporal profile remains identical to the temporal profile of pulses emitted from the free running PQSM laser, with a FWHM duration equal to 600 ps (Fig. 6 ). Let us now consider the spectral broadening in the HNL fiber of the cavity 2. This fiber was a dual concentric core microstructured fiber (DCC MOF), which scanning electronic microscope image of the cross section is shown in Fig. 7 . Its opto-geometrical parameters are: Ge-doped central core diameter of 4.5 µm, ∆n = 15.3 10-3, hole diameter ~1.4 µm, pitch ~2.8 µm, peripheric core thickness ~4 µm. By means of the finite element method, we computed the field distributions and the effective indices of the in-phase and of the out-of-phase supermodes of the fibre (Fig. 8 ). At short wavelengths (λ < 1300 nm), the in-phase supermode (fundamental supermode) and the out-of-phase supermode correspond to the fundamental mode of the central core and to the fundamental mode of the annular core, respectively. The same correspondence with the reversed modes can be seen at long wavelengths (λ > 1400 nm). Because of their very close effective indices in the [1300 nm, 1400 nm] range of wavelengths, the two modes are coupled in this region.

Fig. 6 Temporal profile of the pulses at the output of the source depicted in Fig. 1.

Fig. 7 Cross section of the dual concentric core microstructured fiber displayed by means of a scanning electronic microscope.

Fig. 8 Effective index of the two supermodes of the dual concentric core microstructured fiber (DCC MOF) vs wavelength. Insets: supermodes field distributions at λ = 700 nm and λ = 1600 nm.

From the spectral dependence of the effective index of the fundamental supermode, we derivated the group velocity dispersion of this mode in the fiber (Fig. 9a ), which is cancelled at three wavelengths: 970 nm, 1350 nm and 1730 nm. In our source, the fiber is pumped by the pulse emitted by the PQSM laser at 1064 nm, in the abnormal dispersion regime, near the first zero dispersion wavelength. The spectral broadening of the pump pulse in this abnormal regime (λ < 1350 nm), and then in normal regime from 1350 nm to 1730 nm and finally in the abnormal regime again (over 1730 nm) is governed by complex non-linear phenomena, already discussed in detail in the literature [19

P. K. A. Wai, C. R. Menyuk, Y. C. Lee, and H. H. Chen, “Nonlinear pulse propagation in the neighborhood of the zero-dispersion wavelength of monomode optical fibers,” Opt. Lett. 11(7), 464–466 (1986). [CrossRef] [PubMed]

–21

F. Poletti, P. Horak, and D. J. Richardson, “Soliton spectral tunneling in dispersion controlled holey fibers,” Photon. Technol. Lett. 20(16), 1414–1416 (2008). [CrossRef]

]. Through the dichroic mirror M₃ we measured a supercontinuum of more than 1000 nm width, from 700 nm to 1700 nm (Fig. 9b). At the 4 kHz repetition rate, the mean power detected at the output is 12 mW, corresponding to a 5 kW peak power of the emitted pulses. Considering the supercontinuum spectrum depicted in Fig. 9b, the mean power density is about 12.4 µW/nm, 10.8 µW/nm and 18.7 µW/nm in the [800 nm, 1200 nm], [1200 nm, 1500nm] and [1500 nm, 1800 nm] range, respectively. Thus, the reported pulse source is able to emit broadband pulses at tunable repetition rate, with a very low timing jitter (< 80 ns). To our knowledge, it is the first time that one single laser source is able to exhibit together all these attractive features.

Fig. 9 (a) Dispersion curve of the fundamental supermode in the DCC MOF; (b) pulsed supercontinuum measured at the output of the source.

4. Conclusion

In this paper, we proposed a novel hybrid active-passive laser scheme, based on a passively Q-switched microchip laser cavity optically coupled to a second long cavity including an active modulator and a non linear optical fiber. This laser source emits subnanosecond pulses with the same duration as those from the free running Q-switched microchip laser. In this scheme, the time emission of a pulse is precisely governed by the active modulator, resulting in a decrease of the timing jitter by more than 2 orders of magnitude and making it possible to tune the repetition rate over a large range of frequencies. Furthermore, the possible temporal drift of the pulses is suppressed. Thus, we experimentally demonstrated the emission of 600 ps pulses at repetition rates tunable from few Hz to 4 kHz, with a timing jitter lower than 80 ns, i.e. a 200 to 600-fold reduction compared to that of the free running microchip laser. A dual concentric core microstructured fiber inserted in the second cavity was the center of non linear phenomena resulting in a large spectral broadening of the pulses emitted by the microchip laser, from 700 nm to 1700 nm. Such a low cost and robust source is very attractive for various applications requiring broadband short pulse emission with reduced jitter and tunable repetition rate, such as flow cytometry and spectrally resolved range finding.

Acknowledgments

Florent Doutre and Farid El Bassri are grateful to the French ANRT (National Association for Technical Research) for its financial support via a CIFRE convention with the CILAS Company.

References and links

1.	P. Thony, P. Labeye, V. Marty, R. Templier, P. Bésesty, and E. Molva, “1 µm single-frequency tunable microchip lasers for range finding,” Conference Paper on Advanced Solid State Lasers (ASSL), Poster Session II, Boston, Massachusetts, USA, (1999).
2.	M. Okuno, H. Kano, P. Leproux, V. Couderc, and H. O. Hamaguchi, “Ultrabroadband multiplex CARS microspectroscopy and imaging using a subnanosecond supercontinuum light source in the deep near infrared,” Opt. Lett. 33(9), 923–925 (2008). [CrossRef] [PubMed]
3.	M. Okuno, H. Kano, P. Leproux, V. Couderc, J. P. R. Day, M. Bonn, and H.- Hamaguchi, “Quantitative CARS molecular fingerprinting of single living cells with the use of the maximum entropy method,” Angew. Chem. Int. Ed. 49(38), 6773–6777 (2010). [CrossRef]
4.	H. W. Wang, N. Bao, T. L. Le, C. Lu, and J. X. Cheng, “Microfluidic CARS cytometry,” Opt. Express 16(8), 5782–5789 (2008). [CrossRef] [PubMed]
5.	J. J. Zayhowski and A. Mooradian, “Single-frequency microchip Nd lasers,” Opt. Lett. 14(1), 24–26 (1989). [CrossRef] [PubMed]
6.	D. Nodop, J. Limpert, R. Hohmuth, W. Richter, M. Guina, and A. Tünnermann, “High pulse energy passively quasi-monolithic microchip lasers operating in the sub-100-ps pulse regime,” Opt. Lett. 32(15), 2115–2117 (2007). [CrossRef] [PubMed]
7.	A. Mussot, T. Sylvestre, L. Provino, and H. Maillotte, “Generation of a broadband single-mode supercontinuum in a conventional dispersion-shifted fiber by use of a subnanosecond microchip laser,” Opt. Lett. 28(19), 1820–1822 (2003). [CrossRef] [PubMed]
8.	C. Lesvigne, V. Couderc, A. Tonello, P. Leproux, A. Barthélémy, S. Lacroix, F. Druon, P. Blandin, M. Hanna, and P. Georges, “Visible supercontinuum generation controlled by intermodal four-wave mixing in microstructured fiber,” Opt. Lett. 32(15), 2173–2175 (2007). [CrossRef] [PubMed]
9.	N. D. Lai, M. Brunel, F. Bretenaker, and A. Le Floch, “Stabilization of the repetition rate of passively Q-switched diode pumped solid state lasers,” Appl. Phys. (Berl.) 79(8), 1073–1075 (2001).
10.	J. B. Khurgin, F. Jin, G. Solyar, C. C. Wang, and S. Trivedi, “Cost-effective low timing jitter passively Q-switched diode-pumped solid-state laser with composite pumping pulses,” Appl. Opt. 41(6), 1095–1097 (2002). [CrossRef] [PubMed]
11.	A. F. Shatalov, “Reduction of the pulse repetition period jitter of a diode pumped passively Q-switched solid state laser,” Radiophys Quantum Electron. 52(4), 305–310 (2009).
12.	B. Cole, L. Goldberg, C. W. Trussell, A. Hays, B. W. Schilling, and C. McIntosh, “Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber,” Opt. Express 17(3), 1766–1771 (2009). [CrossRef] [PubMed]
13.	A. Steinmetz, D. Nodop, A. Martin, J. Limpert, and A. Tünnermann, “Reduction of timing jitter in passively Q-switched microchip lasers using self-injection seeding,” Opt. Lett. 35(17), 2885–2887 (2010). [CrossRef] [PubMed]
14.	B. Hansson and M. Arvidsson, “Q-switched microchip laser with 65 ps timing jitter,” Electron. Lett. 36(13), 1123–1124 (2000). [CrossRef]
15.	X. J. Wang and Z. Y. Xu, “Timing jitter and pulse width reduction in a Hybrid Q-switched Cr,Nd:YAG laser,” Chin. Phys. Lett. 23(7), 1800–1802 (2006). [CrossRef]
16.	J. J. Degnan, “Optimization of passively Q-switched lasers,” IEEE J. Quantum Electron. 31(11), 1890–1901 (1995). [CrossRef]
17.	J. J. Zayhowski, “Passively Q-switched microchip lasers,” in Solid-state lasers and applications, ed. A. Sennaroglu, (CRC/Taylor&Francis Ed. 2007).
18.	C. C. Harb, T. C. Ralph, E. H. Huntington, D. E. McClelland, H.-A. Bachor, and I. Freitag, “Intensity noise dependence of Nd-YAG lasers on their diode-laser pump source,” J. Opt. Soc. Am. B 14(11), 2936–2945 (1997). [CrossRef]
19.	P. K. A. Wai, C. R. Menyuk, Y. C. Lee, and H. H. Chen, “Nonlinear pulse propagation in the neighborhood of the zero-dispersion wavelength of monomode optical fibers,” Opt. Lett. 11(7), 464–466 (1986). [CrossRef] [PubMed]
20.	N. Akhmediev and M. Karlsson, “Cherenkov radiation emitted by solitons in optical fibers,” Phys. Rev. A 51(3), 2602–2607 (1995). [CrossRef] [PubMed]
21.	F. Poletti, P. Horak, and D. J. Richardson, “Soliton spectral tunneling in dispersion controlled holey fibers,” Photon. Technol. Lett. 20(16), 1414–1416 (2008). [CrossRef]

OCIS Codes
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.3540) Lasers and laser optics : Lasers, Q-switched

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: September 22, 2011
Revised Manuscript: November 18, 2011
Manuscript Accepted: November 21, 2011
Published: January 5, 2012

Citation
Farid El Bassri, Florent Doutre, Nicolas Mothe, Lionel Jaffres, Dominique Pagnoux, Vincent Couderc, and Alain Jalocha, "Hybrid Q-switched broadband laser source with low timing jitter," Opt. Express 20, 1202-1212 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-2-1202

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References

P. Thony, P. Labeye, V. Marty, R. Templier, P. Bésesty, and E. Molva, “1 µm single-frequency tunable microchip lasers for range finding,” Conference Paper on Advanced Solid State Lasers (ASSL), Poster Session II, Boston, Massachusetts, USA, (1999).
M. Okuno, H. Kano, P. Leproux, V. Couderc, and H. O. Hamaguchi, “Ultrabroadband multiplex CARS microspectroscopy and imaging using a subnanosecond supercontinuum light source in the deep near infrared,” Opt. Lett.33(9), 923–925 (2008). [CrossRef] [PubMed]
M. Okuno, H. Kano, P. Leproux, V. Couderc, J. P. R. Day, M. Bonn, and H.- Hamaguchi, “Quantitative CARS molecular fingerprinting of single living cells with the use of the maximum entropy method,” Angew. Chem. Int. Ed.49(38), 6773–6777 (2010). [CrossRef]
H. W. Wang, N. Bao, T. L. Le, C. Lu, and J. X. Cheng, “Microfluidic CARS cytometry,” Opt. Express16(8), 5782–5789 (2008). [CrossRef] [PubMed]
J. J. Zayhowski and A. Mooradian, “Single-frequency microchip Nd lasers,” Opt. Lett.14(1), 24–26 (1989). [CrossRef] [PubMed]
D. Nodop, J. Limpert, R. Hohmuth, W. Richter, M. Guina, and A. Tünnermann, “High pulse energy passively quasi-monolithic microchip lasers operating in the sub-100-ps pulse regime,” Opt. Lett.32(15), 2115–2117 (2007). [CrossRef] [PubMed]
A. Mussot, T. Sylvestre, L. Provino, and H. Maillotte, “Generation of a broadband single-mode supercontinuum in a conventional dispersion-shifted fiber by use of a subnanosecond microchip laser,” Opt. Lett.28(19), 1820–1822 (2003). [CrossRef] [PubMed]
C. Lesvigne, V. Couderc, A. Tonello, P. Leproux, A. Barthélémy, S. Lacroix, F. Druon, P. Blandin, M. Hanna, and P. Georges, “Visible supercontinuum generation controlled by intermodal four-wave mixing in microstructured fiber,” Opt. Lett.32(15), 2173–2175 (2007). [CrossRef] [PubMed]
N. D. Lai, M. Brunel, F. Bretenaker, and A. Le Floch, “Stabilization of the repetition rate of passively Q-switched diode pumped solid state lasers,” Appl. Phys. (Berl.)79(8), 1073–1075 (2001).
J. B. Khurgin, F. Jin, G. Solyar, C. C. Wang, and S. Trivedi, “Cost-effective low timing jitter passively Q-switched diode-pumped solid-state laser with composite pumping pulses,” Appl. Opt.41(6), 1095–1097 (2002). [CrossRef] [PubMed]
A. F. Shatalov, “Reduction of the pulse repetition period jitter of a diode pumped passively Q-switched solid state laser,” Radiophys Quantum Electron.52(4), 305–310 (2009).
B. Cole, L. Goldberg, C. W. Trussell, A. Hays, B. W. Schilling, and C. McIntosh, “Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber,” Opt. Express17(3), 1766–1771 (2009). [CrossRef] [PubMed]
A. Steinmetz, D. Nodop, A. Martin, J. Limpert, and A. Tünnermann, “Reduction of timing jitter in passively Q-switched microchip lasers using self-injection seeding,” Opt. Lett.35(17), 2885–2887 (2010). [CrossRef] [PubMed]
B. Hansson and M. Arvidsson, “Q-switched microchip laser with 65 ps timing jitter,” Electron. Lett.36(13), 1123–1124 (2000). [CrossRef]
X. J. Wang and Z. Y. Xu, “Timing jitter and pulse width reduction in a Hybrid Q-switched Cr,Nd:YAG laser,” Chin. Phys. Lett.23(7), 1800–1802 (2006). [CrossRef]
J. J. Degnan, “Optimization of passively Q-switched lasers,” IEEE J. Quantum Electron.31(11), 1890–1901 (1995). [CrossRef]
J. J. Zayhowski, “Passively Q-switched microchip lasers,” in Solid-state lasers and applications, ed. A. Sennaroglu, (CRC/Taylor&Francis Ed. 2007).
C. C. Harb, T. C. Ralph, E. H. Huntington, D. E. McClelland, H.-A. Bachor, and I. Freitag, “Intensity noise dependence of Nd-YAG lasers on their diode-laser pump source,” J. Opt. Soc. Am. B14(11), 2936–2945 (1997). [CrossRef]
P. K. A. Wai, C. R. Menyuk, Y. C. Lee, and H. H. Chen, “Nonlinear pulse propagation in the neighborhood of the zero-dispersion wavelength of monomode optical fibers,” Opt. Lett.11(7), 464–466 (1986). [CrossRef] [PubMed]
N. Akhmediev and M. Karlsson, “Cherenkov radiation emitted by solitons in optical fibers,” Phys. Rev. A51(3), 2602–2607 (1995). [CrossRef] [PubMed]
F. Poletti, P. Horak, and D. J. Richardson, “Soliton spectral tunneling in dispersion controlled holey fibers,” Photon. Technol. Lett.20(16), 1414–1416 (2008). [CrossRef]

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