## Noncollinear double-ring optical parametric oscillators with periodically poled KTiOPO_{4}

Optics Express, Vol. 12, Issue 22, pp. 5526-5532 (2004)

http://dx.doi.org/10.1364/OPEX.12.005526

Acrobat PDF (720 KB)

### Abstract

A pulsed self-seeded double-ring optical parametric oscillator realized with periodically poled KTiOPO4 is demonstrated. When pumped from two opposite directions, the cavity supported two automatically aligned, independent, counter-propagating parametric wave pairs whose wavelength could be continuously tuned by varying a single degree of freedom. The tuning range from 1189 nm to 1267 nm has been achieved for the resonant idler waves. The parametric rings could be cross-seeded by using a feedback arrangement. Here, Fourier-domain filtering was utilized to spectrally manipulate the output spectrum of the seeded ring oscillator. Parametric ring oscillator efficiencies of 46 % were achieved.

© 2004 Optical Society of America

## 1. Introduction

1. M. Peltz, U. Bader, A. Borsutzky, R. Wallenstein, J. Hellström, H. Karlsson, V. Pasiskevicius, and F. Laurell, “Optical parametric oscillators for high pulse energy and high average power operation based on large aperture periodically poled KTP and RTA,” Appl. Phys. B **73**, 663–670 (2001) [CrossRef]

2. P. Feve, O. Pacaud, B. Boulanger, B. Menaert, J. Hellström, V. Pasiskevicius, and F. Laurell, “Widely and continuously tunable optical parametric oscillator based on a cylindrical periodically poled KTiOPO4 crystal,” Opt. Let. **26**, 1882–1884 (2001). [CrossRef]

3. V. Smilgevicius, A. Stabinis, A. Piskarskas, V. Pasiskevicius, J. Hellström, S. Wang, and F. Laurell, “Noncollinear optical parametric oscillator with periodically poled KTP,” Opt. Commun. **173**, 365–369 (2000). [CrossRef]

5. S. T. Yang and S. P. Velsko, “Frequency-agile kilohertz repetition-rate optical parametric oscillator based on periodically poled lithium niobate,” Opt. Lett. **24**, 133–135 (1999). [CrossRef]

6. P. Gross, M. E. Klein, H. Ridderbusch, D.-H. Lee, J.-P. Meyn, R. Wallenstein, and K.-J. Boller, “Wide wavelength tuning of an optical parametric oscillator through electro-optic shaping of the gain spectrum,” Opt. Lett. **27**, 1433–1435 (2002). [CrossRef]

7. S. J. Brosnan and R. L. Byer, “Optical parametric oscillator threshold and linewidth studies,” IEEE J. Quantum Elec. **15**, 415–431 (1979). [CrossRef]

8. G. W. Baxter, Y. He, and B. J. Orr, “A pulsed optical parametric oscillator, based on periodically poled lithium niobate (PPLN), for high resolution spectroscopy,” Appl. Phys. B **67**, 753–756 (1998). [CrossRef]

9. A. Borsutzky, “Frequency control of pulsed optical parametric oscillators,” Quantum Semiclass. Opt. **9**, 191–207 (1997). [CrossRef]

10. M. Rahm, G. Anstett, J. Bartschke, T. Bauer, R. Beigang, and R. Wallenstein, “Widely tunable narrow-linewidth nanosecond optical parametric generator with self-injection seeding,” Appl. Phys B **79**, 535–538 (2004). [CrossRef]

11. M. Tiihonen, V. Pasiskevicius, and F. Laurell, “Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP,” in *Advanced Solid-State Photonics*, none eds., Vol. 94 of OSA Proceedings Series (Optical Society of America, Washington, D.C., 2004), (to be published nov. 2004).

## 2. Experiment, results and discussion

3. V. Smilgevicius, A. Stabinis, A. Piskarskas, V. Pasiskevicius, J. Hellström, S. Wang, and F. Laurell, “Noncollinear optical parametric oscillator with periodically poled KTP,” Opt. Commun. **173**, 365–369 (2000). [CrossRef]

_{p}being fixed along the QPM grating vector K

_{g}=2π/Λ, where Λ is the QPM period, the phase-matched signal and idler angles in the small-angle limit can be expressed by:

_{i}, k

_{s}are the moduli for the idler wave and signal wave-vectors, respectively. These dependences have been verified in a simple, 16 mm-long linear OPO cavity, built around the 8 mm-long AR-coated PPKTP crystal with the QPM period of Λ=9.1 µm. The OPO mirrors, had reflectivities of R

_{1}≈80 % and R

_{2}≈99 % for the idler wave and were AR-coated for the signal and the pump beams. The main reasons for choosing idler-resonant OPO configuration were the smaller angular dispersion and, at the same time, the larger diffraction of the idler wave, allowing for generation of narrower spectrum and higher spatial quality beams [11

11. M. Tiihonen, V. Pasiskevicius, and F. Laurell, “Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP,” in *Advanced Solid-State Photonics*, none eds., Vol. 94 of OSA Proceedings Series (Optical Society of America, Washington, D.C., 2004), (to be published nov. 2004).

^{2}=9. The pump beam was focused to a 260 µm radius (e

^{-2}intensity) inside the PPKTP crystal. By tilting the cavity mirrors the OPO idler (signal) was tuned from 1189 nm (968 nm) to 1305 nm (898 nm), this corresponds to the phase-matching angles spanning from θ

_{i}=0 (θ

_{s}=0) to θ

_{i}=45.6 mrad (θ

_{s}=25.9 mrad). Due to the relatively loose focussing conditions the saturated OPO efficiency did not change essentially in the noncollinear configuration. For instance, for the phase-matched angles of θ

_{i}=0 mrad, 18 mrad and 37 mrad the measured OPO efficiencies at the same pump intensity of 104 MW/cm

^{2}, were 67 %, 67 % and 61 %, respectively.

11. M. Tiihonen, V. Pasiskevicius, and F. Laurell, “Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP,” in *Advanced Solid-State Photonics*, none eds., Vol. 94 of OSA Proceedings Series (Optical Society of America, Washington, D.C., 2004), (to be published nov. 2004).

### 2.1 Singly-pumped ring OPO

_{i}=18 mrad, 22.3 mrad and 30.7 mrad, the measured thresholds were 44.5 MW/cm

^{2}, 67 MW/cm

^{2}and 79.5 MW/cm

^{2}or about four-times higher than in the linear cavity at the same noncolinear angles. The parametric gain provided by the 10 mm-long PPKTP was large enough to reach substantial efficiencies of 49%, 48.5% and 34% corresponding to the noncollinear angles of θ

_{i}=18 mrad, 22.3 mrad and 30.7 mrad, and measured at the constant pump intensity of 190 MW/cm

^{2}.

### 2.2 Double-pumped ring OPO

_{p,2}on Fig. 2.) into the cavity from the opposite direction with respect to the forward pump beam (k

_{p,1}on Fig. 2.). When the two beams are overlapping (k

_{p,1}=-k

_{p,2}), the cavity then supports two independent, automatically aligned and counter-propagating parametric ring oscillators. Moreover, the signal and idler outputs of both oscillators are easily separated as shown in Fig. 2, which is useful in certain experimental situations.

### 2.3 Self-seeded double ring OPO

_{1}) into the minus first order (m=-1) with an efficiency of approximately 35 %.

_{1}) OPO (solid circles), unseeded backward-pumped (P

_{2}) OPO (solid squares) and seeded backward-pump OPO (open triangles). The pump depletion was measured for the OPO alignment, corresponding to the non-collinear internal angle of θ

_{i}=22.3 mrad (the conjugate angle for the signal was θ

_{s}=16.7 mrad). The unseeded backward-pumped ring OPO reached threshold at the of 43 MW/cm

^{2}, approximately 1.5 times lower pump intensity than in the forward pumped ring. It is evident from the Fig. 4 that the larger beam waist of the backward pump provides for faster rise in the backward-pumped ring OPO efficiency, the usual feature of the noncollinear parametric interactions [3

3. V. Smilgevicius, A. Stabinis, A. Piskarskas, V. Pasiskevicius, J. Hellström, S. Wang, and F. Laurell, “Noncollinear optical parametric oscillator with periodically poled KTP,” Opt. Commun. **173**, 365–369 (2000). [CrossRef]

^{2}and was limited by the available pump power. When evaluating the cross-seeded ring configuration we kept the forward pump at a constant intensity of 200 MW/cm

^{2}and varied the power of the backward pump. At this forward pump level the seed energy injected into the opposite-directional ring was 14 µJ. In the seeded configuration the backward pump depletion reached nearly 46 % at 84 MW/cm

^{2}generating 103 µJ of the idler and 136 µJ of the signal energy. The measured spatial profile of the idler beam in the far-field was almost perfectly circular and the intensity distribution was Gaussian, with M

^{2}=2.

^{2}=2 as in the case of the OPO idler, the spectral bandwidth of the filter increases to about 54 GHz which concurs very well with the experimental data. In order to reduce the bandwidth, a grating with larger groove density and a Fourier lens with a longer focal length can be used. The use of diffraction-limited beams would also be preferable. It was not our goal during this investigation to reach narrower bandwidth, but it clearly can be done if applications require. Furthermore, in this configuration the seed energy incident on the PPKTP was only 6 nJ, significantly reduced due to imperfections of the stripe-mirror. The resulting seeded idler spectrum from the backward-pumped ring OPO at full pump power is shown in Fig. 5(b), where it is compared with the unseeded OPO spectrum. The broadband pedestal appearing in the seeded spectrum originates from the onset of the competing unseeded operation of the OPO due to the low seed intensity. So the peak-to pedestal ratio was 35 dB at the backward pump intensity of 33 MW/cm

^{2}and it decreased to 6.4 dB for the pump intensity of 68 MW/cm

^{2}. Clearly, the contrast can be increased by using a better quality stripe-mirror and more pump power in the forward-pumped ring OPO. The FWHM of the spectral peak at full pump power was 137 GHz and should be compared with the FWHM of 1.43 THz of the unseeded OPO. In order to further reduce the spectral bandwidth, a diffraction grating with larger groove density and a Fourier lens with a longer focal length can be used. The use of diffraction-limited beams would also be preferable. It was not our goal during this investigation to reach narrower bandwidth, but it clearly can be achieved. In addition to the spectral narrowing, the current ring OPO setup allows one to manipulate and shape the spectrum in other ways as an application requires.

## 3. Conclusion

## References and links

1. | M. Peltz, U. Bader, A. Borsutzky, R. Wallenstein, J. Hellström, H. Karlsson, V. Pasiskevicius, and F. Laurell, “Optical parametric oscillators for high pulse energy and high average power operation based on large aperture periodically poled KTP and RTA,” Appl. Phys. B |

2. | P. Feve, O. Pacaud, B. Boulanger, B. Menaert, J. Hellström, V. Pasiskevicius, and F. Laurell, “Widely and continuously tunable optical parametric oscillator based on a cylindrical periodically poled KTiOPO4 crystal,” Opt. Let. |

3. | V. Smilgevicius, A. Stabinis, A. Piskarskas, V. Pasiskevicius, J. Hellström, S. Wang, and F. Laurell, “Noncollinear optical parametric oscillator with periodically poled KTP,” Opt. Commun. |

4. | M. J. Missey, V. Dominic, and P. E. Powers, “Periodically poled lithium niobate monolithic nanosecond optical parametric oscillators and generators,” Opt. Lett. |

5. | S. T. Yang and S. P. Velsko, “Frequency-agile kilohertz repetition-rate optical parametric oscillator based on periodically poled lithium niobate,” Opt. Lett. |

6. | P. Gross, M. E. Klein, H. Ridderbusch, D.-H. Lee, J.-P. Meyn, R. Wallenstein, and K.-J. Boller, “Wide wavelength tuning of an optical parametric oscillator through electro-optic shaping of the gain spectrum,” Opt. Lett. |

7. | S. J. Brosnan and R. L. Byer, “Optical parametric oscillator threshold and linewidth studies,” IEEE J. Quantum Elec. |

8. | G. W. Baxter, Y. He, and B. J. Orr, “A pulsed optical parametric oscillator, based on periodically poled lithium niobate (PPLN), for high resolution spectroscopy,” Appl. Phys. B |

9. | A. Borsutzky, “Frequency control of pulsed optical parametric oscillators,” Quantum Semiclass. Opt. |

10. | M. Rahm, G. Anstett, J. Bartschke, T. Bauer, R. Beigang, and R. Wallenstein, “Widely tunable narrow-linewidth nanosecond optical parametric generator with self-injection seeding,” Appl. Phys B |

11. | M. Tiihonen, V. Pasiskevicius, and F. Laurell, “Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP,” in |

12. | J.-C. Diels and W. Rudolph, |

**OCIS Codes**

(190.4360) Nonlinear optics : Nonlinear optics, devices

(190.4410) Nonlinear optics : Nonlinear optics, parametric processes

(190.4970) Nonlinear optics : Parametric oscillators and amplifiers

**ToC Category:**

Research Papers

**History**

Original Manuscript: September 14, 2004

Revised Manuscript: October 14, 2004

Published: November 1, 2004

**Citation**

Mikael Tiihonen, Valdas Pasiskevicius, and Fredrik Laurell, "Noncollinear double-ring optical parametric oscillators with periodically poled KTiOPO4," Opt. Express **12**, 5526-5532 (2004)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-12-22-5526

Sort: Journal | Reset

### References

- M. Peltz, U. Bader, A.Borsutzky, R. Wallenstein, J. Hellström, H. Karlsson, V.Pasiskevicius and F. Laurell, �??Optical parametric oscillators for high pulse energy and high average power operation based on large aperture periodically poled KTP and RTA,�?? Appl. Phys. B 73, 663-670 (2001) [CrossRef]
- P. Feve, O. Pacaud, B. Boulanger, B. Menaert, J. Hellström, V. Pasiskevicius and F. Laurell, �??Widely and continuously tunable optical parametric oscillator based on a cylindrical periodically poled KTiOPO4 crystal,�?? Opt. Let. 26, 1882-1884 (2001). [CrossRef]
- V. Smilgevicius, A. Stabinis, A. Piskarskas, V. Pasiskevicius, J. Hellström, S. Wang and F. Laurell, �??Noncollinear optical parametric oscillator with periodically poled KTP,�?? Opt. Commun. 173, 365-369 (2000). [CrossRef]
- M. J. Missey, V. Dominic and P. E. Powers, �??Periodically poled lithium niobate monolithic nanosecond optical parametric oscillators and generators,�?? Opt. Lett. 24, 1227-1229 (1999). [CrossRef]
- S. T. Yang and S. P. Velsko, �??Frequency-agile kilohertz repetition-rate optical parametric oscillator based on periodically poled lithium niobate,�?? Opt. Lett. 24, 133-135 (1999). [CrossRef]
- P. Gross, M. E. Klein, H. Ridderbusch, D.-H. Lee, J.-P. Meyn, R. Wallenstein, K.-J.Boller, �??Wide wavelength tuning of an optical parametric oscillator through electro-optic shaping of the gain spectrum,�?? Opt. Lett. 27, 1433-1435 (2002). [CrossRef]
- S. J. Brosnan and R. L. Byer, �??Optical parametric oscillator threshold and linewidth studies,�?? IEEE J. Quantum Elec. 15, 415-431 (1979). [CrossRef]
- G. W. Baxter, Y. He and B. J. Orr, �??A pulsed optical parametric oscillator, based on periodically poled lithium niobate (PPLN), for high resolution spectroscopy,�?? Appl. Phys. B 67, 753-756 (1998). [CrossRef]
- A. Borsutzky, �??Frequency control of pulsed optical parametric oscillators,�?? Quantum Semiclass. Opt. 9, 191-207 (1997). [CrossRef]
- M. Rahm, G. Anstett, J. Bartschke, T. Bauer, R. Beigang and R. Wallenstein, �??Widely tunable narrow-linewidth nanosecond optical parametric generator with self-injection seeding,�?? Appl. Phys B 79, 535-538 (2004). [CrossRef]
- M. Tiihonen, V. Pasiskevicius and F. Laurell, �??Spectral and spatial limiting in idler-resonant optical parametric oscillator with PPKTP,�?? in Advanced Solid-State Photonics, none eds., Vol. 94 of OSA Proceedings Series (Optical Society of America, Washington, D.C., 2004), (to be published nov. 2004).
- J.-C. Diels and W. Rudolph, Ultrashort Laser Pulse Phenomena (Academic Press, 1996), Chap. 7.

## Cited By |
Alert me when this paper is cited |

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

### Figures

Fig 1. |
Fig. 2. |
Fig. 3. |

Fig. 4. |
Fig. 5. (a) |
Fig. 5. (b) |

« Previous Article | Next Article »

OSA is a member of CrossRef.