High-power, single-frequency, continuous-wave optical parametric oscillator employing a variable reflectivity volume Bragg grating Peter Zeil,* Nicky Thilmann, Valdas Pasiskevicius, and Fredrik Laurell Department of Applied Physics, Royal Institute of Technology, Roslagstullsbacken 21, 10691 Stockholm, Sweden * [email protected]
Abstract: A continuous-wave singly-resonant optical parametric oscillator (SRO) with an optimum extraction efficiency, that can be adjusted independent of the pump power, is demonstrated. The scheme employs a variable-reflectivity volume Bragg grating (VBG) as the output coupler of a ring cavity, omitting any additional intra-cavity elements. In this configuration, we obtained a 75%-efficient SRO with a combined signal (19 W @ 1.55 µm) and idler (11 W @ 3.4 µm) output power of 30 W. © 2014 Optical Society of America OCIS codes: (190.4410) Nonlinear optics, parametric processes; (190.4970) Parametric oscillators and amplifiers; (230.1480) Bragg reflectors.
References and links 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
S. M. Cristescu, S. T. Persijn, S. te Lintel Hekkert, and F. J. M. Harren, “Laser-based systems for trace gas detection in life sciences,” Appl. Phys. B 92(3), 343–349 (2008). K. Marushkevich, M. Siltanen, M. Räsänen, L. Halonen, and L. Khriachtchev, “Identification of New Dimers of Formic Acid: The Use of a Continuous-Wave Optical Parametric Oscillator in Matrix Isolation Experiments,” J. Phys. Chem. Lett. 2(7), 695–699 (2011). D. H. Titterton, “A review of the development of optical countermeasures,” Proc. SPIE 5615, 1–15 (2004). P. Gross, M. E. Klein, T. Walde, K.-J. Boller, M. Auerbach, P. Wessels, and C. Fallnich, “Fiber-laser-pumped continuous-wave singly resonant optical parametric oscillator,” Opt. Lett. 27(6), 418–420 (2002). I. D. Lindsay, B. Adhimoolam, P. Groß, M. E. Klein, and K.-J. Boller, “110GHz rapid, continuous tuning from an optical parametric oscillator pumped by a fiber-amplified DBR diode laser,” Opt. Express 13(4), 1234–1239 (2005). A. Henderson and R. Stafford, “Low threshold, singly-resonant CW OPO pumped by an all-fiber pump source,” Opt. Express 14(2), 767–772 (2006). A. Henderson and P. Esquinasi, “23-watt 77% efficient CW OPO pumped by a fiber laser,” Proc. SPIE 7580, 75800D (2010). R. Sowade, I. Breunig, J. Kiessling, and K. Buse, “Influence of the pump threshold on the single-frequency output power of singly resonant optical parametric oscillators,” Appl. Phys. B 96(1), 25–28 (2009). A. Henderson and R. Stafford, “Spectral broadening and stimulated Raman conversion in a continuous-wave optical parametric oscillator,” Opt. Lett. 32(10), 1281–1283 (2007). L. E. Myers and W. R. Bosenberg, “Periodically poled lithium niobate and quasi-phase-matched optical parametric oscillators,” IEEE J. Quantum Electron. 33(10), 1663–1672 (1997). S. Yang, R. Eckardt, and R. Byer, “Power and spectral characteristics of continuous-wave parametric oscillators: the doubly to singly resonant transition,” J. Opt. Soc. Am. B 10(9), 1684–1695 (1993). S. Guha, “Focusing dependence of the efficiency of a singly resonant optical parametric oscillator,” Appl. Phys. B 66(6), 663–675 (1998). C. Phillips and M. Fejer, “Stability of the singly resonant optical parametric oscillator,” J. Opt. Soc. Am. B 27(12), 2687–2699 (2010). S. Chaitanya Kumar, R. Das, G. K. Samanta, and M. Ebrahim-Zadeh, “Optimally-output-coupled, 17.5 W, fiberlaser-pumped continuous-wave optical parametric oscillator,” Appl. Phys. B 102(1), 31–35 (2011). K. Devi, S. C. Kumar, A. Esteban-Martin, and M. Ebrahim-Zadeh, “Antiresonant ring output-coupled continuous-wave optical parametric oscillator,” Opt. Express 20(17), 19313–19321 (2012). B. Jacobsson, V. Pasiskevicius, F. Laurell, E. Rotari, V. Smirnov, and L. Glebov, “Tunable narrowband optical parametric oscillator using a transversely chirped Bragg grating,” Opt. Lett. 34(4), 449–451 (2009). N. Thilmann, B. Jacobsson, C. Canalias, V. Pasiskevicius, and F. Laurell, “A narrowband optical parametric oscillator tunable over 6.8 THz through degeneracy with a transversely-chirped volume Bragg grating,” Appl. Phys. B 105(2), 239–244 (2011).
#224530 - $15.00 USD Received 8 Oct 2014; revised 7 Nov 2014; accepted 14 Nov 2014; published 21 Nov 2014 (C) 2014 OSA 1 December 2014 | Vol. 22, No. 24 | DOI:10.1364/OE.22.029907 | OPTICS EXPRESS 29907
18. M. Vainio and L. Halonen, “Stable operation of a cw optical parametric oscillator near the signal-idler degeneracy,” Opt. Lett. 36(4), 475–477 (2011). 19. M. Vainio, C. Ozanam, V. Ulvila, and L. Halonen, “Tuning and stability of a singly resonant continuous-wave optical parametric oscillator close to degeneracy,” Opt. Express 19(23), 22515–22527 (2011). 20. P. Zeil, V. Pasiskevicius, and F. Laurell, “Efficient spectral control and tuning of a high-power narrow-linewidth Yb-doped fiber laser using a transversely chirped volume Bragg grating,” Opt. Express 21(4), 4027–4035 (2013). 21. J. E. Hellstrom, B. Jacobsson, V. Pasiskevicius, and F. Laurell, “Finite beams in reflective volume Bragg gratings: theory and experiments,” IEEE J. Quantum Electron. 44(1), 81–89 (2008). 22. R. L. Sutherland, Handbook of Nonlinear Optics (Marcel Dekker, 1996). 23. G. D. Boyd and D. A. Kleinman, “Parametric Interaction of Focused Gaussian Light Beams,” J. Appl. Phys. 39(8), 3597–3639 (1968). 24. S. T. Lin, Y. Y. Lin, Y. C. Huang, A. C. Chiang, and J. T. Shy, “Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator,” Opt. Lett. 33(20), 2338–2340 (2008).
1. Introduction Mid-infrared continuous-wave singly-resonant optical parametric oscillators (SROs) are used in various spectroscopic applications such as trace gas analysis, as well as in different industrial and security applications, for instance countermeasures against heat-seeking missiles [1–3]. With the emergence of reliable fiber-laser pump sources with versatile tuning capabilities, the prospect of cost-efficient SROs addressing various wavelength ranges has attracted increased interest [4–6]. In particular, the improved access to considerable pump power has enabled high-power SROs with output powers in excess of 20 W [7]. However, operating SROs at these power levels requires accurate control of the circulating intra-cavity power in order to reach both optimum conversion efficiency to the idler wave [8] and suppress detrimental effects, such as thermal loading, cascaded nonlinear conversion processes, and Raman scattering, all of which can diminish spatial and spectral quality of the output signals [9, 10]. It has been shown theoretically that an optimal ratio of pump to threshold power of (π/2)2 (roughly 2.5) ensures maximal power extraction from SROs described with plane waves [11]. Other studies showed that this value remains unaffected even when collimated Gaussian beams are used to describe the interacting fields [12]. However, it has also been suggested that SROs would be susceptible to modulation instabilities at high pump intensities, which could even require pumping with less than the optimal ratio [13]. These difficulties have been recognized and the introduction of sufficient output coupling by using a set of different mirrors as output couplers [14] or variable output coupling through an anti-resonant ring interferometer [15] have been used to operate SROs with optimal extraction efficiency. However, these approaches either require a time consuming search for the optimal mirror, or some extra optical elements that increase the internal losses and space requirements. In this work, we propose and demonstrate the utilization of a volume Bragg grating (VBG) with variable reflectivity along the transverse direction as an output coupler, which allows continuous variation of the SROs threshold by means of a straightforward one-dimensional translation of the grating. Moreover, using a VBG as a cavity delimiter also obviates the need for any additional intra-cavity elements i.e. etalons for frequency stabilization. Although, the tuning capabilities of such a cavity configuration is reduced at first glance, it was demonstrated earlier that the implementation of a transversal chirp of the VBGs design wavelength is an efficient opportunity to reintroduce wavelength tuning of OPO cavities [16,17]. This would require a VBG reflectivity profile where along one direction of the grating the reflectivity is varied, while in the other direction the spectral position of the reflectivity peak changes gradually. Additionally, in previous work on VBG-locked SROs [18, 19] it was demonstrated, that by employing the VBG in a tilted configuration within a ring cavity single-longitudinal mode output signals are easily achieved.
#224530 - $15.00 USD Received 8 Oct 2014; revised 7 Nov 2014; accepted 14 Nov 2014; published 21 Nov 2014 (C) 2014 OSA 1 December 2014 | Vol. 22, No. 24 | DOI:10.1364/OE.22.029907 | OPTICS EXPRESS 29908
2. Experimental setup The schematic of the experimental SRO configuration is given in Fig. 1. The SRO was pumped with an in-house built continuous wave Yb-doped fiber laser [20]. The pump laser provided low-noise (
Abstract: A continuous-wave singly-resonant optical parametric oscillator (SRO) with an optimum extraction efficiency, that can be adjusted independent of the pump power, is demonstrated. The scheme employs a variable-reflectivity volume Bragg grating (VBG) as the output coupler of a ring cavity, omitting any additional intra-cavity elements. In this configuration, we obtained a 75%-efficient SRO with a combined signal (19 W @ 1.55 µm) and idler (11 W @ 3.4 µm) output power of 30 W. © 2014 Optical Society of America OCIS codes: (190.4410) Nonlinear optics, parametric processes; (190.4970) Parametric oscillators and amplifiers; (230.1480) Bragg reflectors.
References and links 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
S. M. Cristescu, S. T. Persijn, S. te Lintel Hekkert, and F. J. M. Harren, “Laser-based systems for trace gas detection in life sciences,” Appl. Phys. B 92(3), 343–349 (2008). K. Marushkevich, M. Siltanen, M. Räsänen, L. Halonen, and L. Khriachtchev, “Identification of New Dimers of Formic Acid: The Use of a Continuous-Wave Optical Parametric Oscillator in Matrix Isolation Experiments,” J. Phys. Chem. Lett. 2(7), 695–699 (2011). D. H. Titterton, “A review of the development of optical countermeasures,” Proc. SPIE 5615, 1–15 (2004). P. Gross, M. E. Klein, T. Walde, K.-J. Boller, M. Auerbach, P. Wessels, and C. Fallnich, “Fiber-laser-pumped continuous-wave singly resonant optical parametric oscillator,” Opt. Lett. 27(6), 418–420 (2002). I. D. Lindsay, B. Adhimoolam, P. Groß, M. E. Klein, and K.-J. Boller, “110GHz rapid, continuous tuning from an optical parametric oscillator pumped by a fiber-amplified DBR diode laser,” Opt. Express 13(4), 1234–1239 (2005). A. Henderson and R. Stafford, “Low threshold, singly-resonant CW OPO pumped by an all-fiber pump source,” Opt. Express 14(2), 767–772 (2006). A. Henderson and P. Esquinasi, “23-watt 77% efficient CW OPO pumped by a fiber laser,” Proc. SPIE 7580, 75800D (2010). R. Sowade, I. Breunig, J. Kiessling, and K. Buse, “Influence of the pump threshold on the single-frequency output power of singly resonant optical parametric oscillators,” Appl. Phys. B 96(1), 25–28 (2009). A. Henderson and R. Stafford, “Spectral broadening and stimulated Raman conversion in a continuous-wave optical parametric oscillator,” Opt. Lett. 32(10), 1281–1283 (2007). L. E. Myers and W. R. Bosenberg, “Periodically poled lithium niobate and quasi-phase-matched optical parametric oscillators,” IEEE J. Quantum Electron. 33(10), 1663–1672 (1997). S. Yang, R. Eckardt, and R. Byer, “Power and spectral characteristics of continuous-wave parametric oscillators: the doubly to singly resonant transition,” J. Opt. Soc. Am. B 10(9), 1684–1695 (1993). S. Guha, “Focusing dependence of the efficiency of a singly resonant optical parametric oscillator,” Appl. Phys. B 66(6), 663–675 (1998). C. Phillips and M. Fejer, “Stability of the singly resonant optical parametric oscillator,” J. Opt. Soc. Am. B 27(12), 2687–2699 (2010). S. Chaitanya Kumar, R. Das, G. K. Samanta, and M. Ebrahim-Zadeh, “Optimally-output-coupled, 17.5 W, fiberlaser-pumped continuous-wave optical parametric oscillator,” Appl. Phys. B 102(1), 31–35 (2011). K. Devi, S. C. Kumar, A. Esteban-Martin, and M. Ebrahim-Zadeh, “Antiresonant ring output-coupled continuous-wave optical parametric oscillator,” Opt. Express 20(17), 19313–19321 (2012). B. Jacobsson, V. Pasiskevicius, F. Laurell, E. Rotari, V. Smirnov, and L. Glebov, “Tunable narrowband optical parametric oscillator using a transversely chirped Bragg grating,” Opt. Lett. 34(4), 449–451 (2009). N. Thilmann, B. Jacobsson, C. Canalias, V. Pasiskevicius, and F. Laurell, “A narrowband optical parametric oscillator tunable over 6.8 THz through degeneracy with a transversely-chirped volume Bragg grating,” Appl. Phys. B 105(2), 239–244 (2011).
#224530 - $15.00 USD Received 8 Oct 2014; revised 7 Nov 2014; accepted 14 Nov 2014; published 21 Nov 2014 (C) 2014 OSA 1 December 2014 | Vol. 22, No. 24 | DOI:10.1364/OE.22.029907 | OPTICS EXPRESS 29907
18. M. Vainio and L. Halonen, “Stable operation of a cw optical parametric oscillator near the signal-idler degeneracy,” Opt. Lett. 36(4), 475–477 (2011). 19. M. Vainio, C. Ozanam, V. Ulvila, and L. Halonen, “Tuning and stability of a singly resonant continuous-wave optical parametric oscillator close to degeneracy,” Opt. Express 19(23), 22515–22527 (2011). 20. P. Zeil, V. Pasiskevicius, and F. Laurell, “Efficient spectral control and tuning of a high-power narrow-linewidth Yb-doped fiber laser using a transversely chirped volume Bragg grating,” Opt. Express 21(4), 4027–4035 (2013). 21. J. E. Hellstrom, B. Jacobsson, V. Pasiskevicius, and F. Laurell, “Finite beams in reflective volume Bragg gratings: theory and experiments,” IEEE J. Quantum Electron. 44(1), 81–89 (2008). 22. R. L. Sutherland, Handbook of Nonlinear Optics (Marcel Dekker, 1996). 23. G. D. Boyd and D. A. Kleinman, “Parametric Interaction of Focused Gaussian Light Beams,” J. Appl. Phys. 39(8), 3597–3639 (1968). 24. S. T. Lin, Y. Y. Lin, Y. C. Huang, A. C. Chiang, and J. T. Shy, “Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator,” Opt. Lett. 33(20), 2338–2340 (2008).
1. Introduction Mid-infrared continuous-wave singly-resonant optical parametric oscillators (SROs) are used in various spectroscopic applications such as trace gas analysis, as well as in different industrial and security applications, for instance countermeasures against heat-seeking missiles [1–3]. With the emergence of reliable fiber-laser pump sources with versatile tuning capabilities, the prospect of cost-efficient SROs addressing various wavelength ranges has attracted increased interest [4–6]. In particular, the improved access to considerable pump power has enabled high-power SROs with output powers in excess of 20 W [7]. However, operating SROs at these power levels requires accurate control of the circulating intra-cavity power in order to reach both optimum conversion efficiency to the idler wave [8] and suppress detrimental effects, such as thermal loading, cascaded nonlinear conversion processes, and Raman scattering, all of which can diminish spatial and spectral quality of the output signals [9, 10]. It has been shown theoretically that an optimal ratio of pump to threshold power of (π/2)2 (roughly 2.5) ensures maximal power extraction from SROs described with plane waves [11]. Other studies showed that this value remains unaffected even when collimated Gaussian beams are used to describe the interacting fields [12]. However, it has also been suggested that SROs would be susceptible to modulation instabilities at high pump intensities, which could even require pumping with less than the optimal ratio [13]. These difficulties have been recognized and the introduction of sufficient output coupling by using a set of different mirrors as output couplers [14] or variable output coupling through an anti-resonant ring interferometer [15] have been used to operate SROs with optimal extraction efficiency. However, these approaches either require a time consuming search for the optimal mirror, or some extra optical elements that increase the internal losses and space requirements. In this work, we propose and demonstrate the utilization of a volume Bragg grating (VBG) with variable reflectivity along the transverse direction as an output coupler, which allows continuous variation of the SROs threshold by means of a straightforward one-dimensional translation of the grating. Moreover, using a VBG as a cavity delimiter also obviates the need for any additional intra-cavity elements i.e. etalons for frequency stabilization. Although, the tuning capabilities of such a cavity configuration is reduced at first glance, it was demonstrated earlier that the implementation of a transversal chirp of the VBGs design wavelength is an efficient opportunity to reintroduce wavelength tuning of OPO cavities [16,17]. This would require a VBG reflectivity profile where along one direction of the grating the reflectivity is varied, while in the other direction the spectral position of the reflectivity peak changes gradually. Additionally, in previous work on VBG-locked SROs [18, 19] it was demonstrated, that by employing the VBG in a tilted configuration within a ring cavity single-longitudinal mode output signals are easily achieved.
#224530 - $15.00 USD Received 8 Oct 2014; revised 7 Nov 2014; accepted 14 Nov 2014; published 21 Nov 2014 (C) 2014 OSA 1 December 2014 | Vol. 22, No. 24 | DOI:10.1364/OE.22.029907 | OPTICS EXPRESS 29908
2. Experimental setup The schematic of the experimental SRO configuration is given in Fig. 1. The SRO was pumped with an in-house built continuous wave Yb-doped fiber laser [20]. The pump laser provided low-noise (
