Broadband second-harmonic and sum-frequency generation with a long-wave infrared laser in AgGaGe5Se12.

Using an 8 µm long-wave infrared laser as the fundamental wave, we achieved second-harmonic generation (SHG) and sum-frequency generation simultaneously in AgGaGe5Se12 and obtained a 4 µm laser output. Among them, SHG was achieved in the 173 nm spectral range of the fundamental wave, which was consistent with theoretical calculations. The average power of the obtained 4 µm laser was 41 mW, corresponding to an optical-to-optical conversion efficiency of 3.2%. The measured temperature acceptance bandwidth (LδT) (FWHM) was 50 K·cm; the angular acceptance bandwidth (Lδθ) (FWHM) was 13.3 mrad·cm; and the average absorption coefficient in the wavelength range of 0.86-11.30 µm was 0.07cm-1. In addition, the spectral acceptance bandwidth (Lδλ) of fundamental wave in AgGaGe5Se12 SHG and the spectral gain bandwidth of frequency downconversion in AgGaGe5Se12 were calculated. In view of the small absorption coefficient, the large temperature acceptance bandwidth, and the large spectral gain bandwidth, we conclude that AgGaGe5Se12 is a suitable nonlinear crystal for high-power short/mid/long-wave infrared lasers and frequency conversions of nanosecond-femtosecond infrared lasers. These results are conducive to the further development of AgGaGe5Se12 lasers.

[1]  O. A. Rulev,et al.  Frequency conversion of mid-IR lasers into the long-wavelength domain of 12-20 µm with AgGaSe2, BaGa2GeSe6 and PbIn6Te10 nonlinear crystals. , 2019, Optics express.

[2]  B. Yao,et al.  High-efficiency, tunable 8-9 μm BaGa4Se7optical parametric oscillator pumped at 21 μm , 2018, Optical Materials Express.

[3]  Wang Li,et al.  Growth and characterization of mid-far infrared optical material CdSe crystal , 2018, Optical Materials Express.

[4]  S. Hädrich,et al.  100 kHz, femtosecond, 4-10 μm tunable, AgGaSe2-based OPA pumped by a CPA Tm:fiber laser system , 2017 .

[5]  Patricia L. Inacio,et al.  Angle noncritical phase-matched second-harmonic generation in the monoclinic crystal BaGa₄Se₇. , 2015, Optics letters.

[6]  M. Qi,et al.  Growth and optical properties of single AgGaGe5Se12 (AGGSe) crystal , 2015 .

[7]  Valentin Petrov,et al.  Difference-frequency generation of ultrashort pulses in the mid-IR using Yb-fiber pump systems and AgGaSe(2). , 2015, Optics express.

[8]  D. Kahler,et al.  Quaternary AgGaGenSe2(n+1) crystals for NLO applications , 2010 .

[9]  V. Petrov,et al.  Orthorhombic nonlinear crystals of AgxGaxGe1−xSe2 for the mid-infrared spectral range , 2009 .

[10]  Peter G. Schunemann,et al.  Improved NLO crystals for mid-IR laser applications , 2007, SPIE LASE.

[11]  Peter G. Schunemann,et al.  Growth of new quaternary nonlinear optical crystals for 1-micron-pumped mid-IR generation , 2006, SPIE LASE.

[12]  Peter G. Schunemann,et al.  Horizontal gradient freeze growth of AgGaGeS4 and AgGaGe5Se12 , 2006 .

[13]  V. Petrov,et al.  Phase-matching and femtosecond difference-frequency generation in the quaternary semiconductor AgGaGe5Se12. , 2004, Applied optics.

[14]  S. Marzenell,et al.  Synchronously pumped femtosecond optical parametric oscillator based on AgGaSe2 tunable from 2 μm to 8 μm , 1999 .

[15]  S. Tochitsky,et al.  Efficient continuous-wave frequency doubling of a tunable CO(2) laser in AgGaSe(2). , 1997, Applied optics.

[16]  G. D. Boyd,et al.  Linear and nonlinear optical properties of some ternary selenides , 1972 .

[17]  R. Miller.  Second harmonic generation with a broadband optical maser , 1968 .