Numerical study of multiline CO laser frequency conversion in a ZnGeP2 crystal to the THz range

A numerical simulation was performed for frequency conversion of multiline CO laser radiation to the THz range by difference frequency generation in a ZnGeP2 crystal. It was shown that the difference frequencies spectrum can be tuned in the wavelength interval of 70–1300 μm by tuning the phase-matching angle in the range of 11° to 55°. The maximal peak power of difference frequencies radiation (integral over the spectrum) was ~0.23 W at 45° phase-matching angle, which corresponds to a peak power conversion efficiency of 6 × 10−5

Three-stage frequency conversion of sub-microsecond multiline CO laser pulse in a single ZnGeP2 crystal

Broadband three-stage frequency conversion of multiline sub-microsecond CO laser radiation in a single sample of ZnGeP2 crystal was experimentally and numerically studied for the first time, to the best of our knowledge. As a result, the hybrid laser system emitted more than 200 narrow spectral lines within the 2.4–6.2 μm spectral range. The measured conversion efficiencies of the first, second, and third stages were about 4.8%, 0.4%, and 0.05%, respectively. Our numerical simulation demonstrated that the third stage of this frequency conversion can extend the laser system spectrum toward the shorter wavelength of 2.2 μm

CO laser sum-frequency comb for atmosphere sensing

Sum-frequency spectrum of non-selective (multi-line)CO laser radiation generated in ZnGeP2 crystal under noncritical spectral phase-matching conditions was experimentally studied with spectral resolution of ∼0.1 cm⁻¹. The number of spectral lines for this spectrum was found to be about an order of magnitude larger than for previously reported one. Its spectral structure looked like a broadband mid-IR comb of multi-line groups having complicated substructure. That is attractive for the atmosphere sounding by both differential absorption technique and absorption line profile spectroscopy. A list of the atmosphere gases and pollutants that could be detected by these procedures was considered. An opportunity of absorption line profile measuring by means of CO laser sum-frequency comb was experimentally demonstrated for CO2 molecules

Frequency conversion of mode-locked and Q-switched CO laser radiation with efficiency up to 37%

Frequency conversion of CO laser radiation was experimentally studied in ZnGeP2 and GaSe nonlinear crystals. T

Temperature phase-matching tuning of nonlinear ZnGeP2 crystal for frequency conversion under noncritical spectral phase-matching

Temperature dependences of nonlinear ZnGeP2 crystal indices within the wavelength range of 5.0–6.2 μm (around noncritical spectral phase-matching) were examined with a frequency-selective Q-switched CO laser. The correct dependences were found and applied for numerical study of the spectrum tuning by the crystal temperature changing under the broadband CO laser sum frequency generation. The latter was experimentally studied for the crystal temperature range from the room one up to 145 °C. Requirements for ZnGeP2 crystal temperature changing needed for broadband frequency conversion of 5–7.5 μm radiation were formulated

Frequency conversion of mode-locked and Q-switched CO laser radiation with efficiency up to 37%

Frequency conversion of CO laser radiation was experimentally studied in ZnGeP2 and GaSe nonlinear crystals. T