CC BY
11LS-I-5
Nonlinear conversion of broadband mid-IR laser radiation into the wavelength range of ~2 - 20 micron
A. Ionin1, I. Kinyaevskiy1, Y. Klimachev1, A. Kotkov1, A. Kozlov1, A. Sagitova1, D. Sinitsyn1, L. Seleznev1
1P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Division of Quantum Radiophysics, Moscow, Russian Federation
The mid-IR laser sources operating within the molecular fingerprint region (the wavelengths of ~2-20 p,m) are being actively developed for various important applications. To cover the mid-IR range with discrete bright spectral lines, a frequency conversion of high-peak power mid-IR molecular gas lasers in different nonlinear crystals was studied.
A hybrid laser system based on repetitively pulsed multiline carbon monoxide (CO) and carbon dioxide (CO2) lasers including slab RF discharge lasers with synchronous Q-switching was developed. Its spectrum is presented in Fig.1. Multiline Q-switched CO laser emitted simultaneously up to 150 spectral lines within 5.0-7.5 p,m in a single microsecond pulse. Multiline Q-switched CO2 laser emitted simultaneously up to 9 spectral lines within 9.25-9.59 p,m in a single microsecond pulse as well. To extend the laser system spectrum down to 2.5-3.7 p,m range, broadband sum frequency (SF) generation of CO laser radiation in ZnGeP2 crystal was implemented (CO_SF). In turn, CO_SF emission lines were mixed with the residual CO laser lines in the same crystal, which resulted in generation of difference frequencies within 4.3-5.0 p,m and 7.5-8.3 p,m spectral ranges (CO_DF).
2 4 6 8 10 12 14 16 18 (im
Fig. 1.
To extend the laser system spectrum toward the near-IR range of 1.7-1.9 p,m, third harmonic generation of CO laser (CO_TH) in BaGa2GeSe6 crystal was performed (sum frequency generation of CO_SF lines and the residual CO laser lines). Sum frequency generation of multiline CO and CO2 lasers radiation in GaSe crystal (CO+CO2) covered 3.3-3.8 p,m range. The highest efficiency of difference frequency generation between CO and CO2 lasers lines (CO-CO2) was obtained in PbIn6Te10 crystal, which allowed us to cover 11.5-19.3 p,m range by dozens of narrow spectral lines.
The research was supported by the Russian Science Foundation (Project No 16-19-10619).
