Broadband two-stage frequency conversion of CO laser in AgGaSe_2 crystal

Abstract

For the first time, to the best of our knowledge, a broadband two-stage frequency conversion of multiline CO laser radiation was theoretically and experimentally demonstrated in a single AgGaSe₂ crystal. The first stage is sum frequency generation of CO laser radiation. The second stage is concurrent difference frequency generation within 4.3-4.9 μm spectral range when mixing sum frequency radiation with the pump radiation in the same AgGaSe₂ crystal. Internal sum frequency generation efficiency of multiline CO laser was up to 1%, while internal difference frequency generation efficiency was up to 0.065%.

Influence of multi-line CO laser focusing on broadband sum-frequency generation

“…One more attractive point for CO laser research and applications is a noncritical spectral phase-matching in widely-known mid-IR nonlinear crystals such as ZnGeP2, GaSe, AgGaSe2 [6]. Due to noncritical spectral phase-matching, the broadband two-stage frequency conversion of multi-line CO laser radiation was obtained in ZnGeP2, [7,8] and AgGaSe2 [9] crystals. Similar method of broadband phase-matching frequency conversion was suggested for generation and amplification of ultra-short mid-IR laser pulses [10][11][12], which has many important applications, such as high harmonic generation [13], for instance.…”

Sum frequency generation under conversion of Q-switched cryogenic slab RF discharge CO laser radiation in ZnGeP2

“…Therefore, the CO laser radiation covers the spectral ranges where the absorption bands of various atmospheric components and strong pollutants, explosives and drugs are located, and their reliable detection is quite needed. Moreover, the CO laser radiation spectrum can be significantly extended by the sum and difference frequency conversion in nonlinear crystals [4][5][6][7][8][9][10], and this dramatically enhances the potential of such a laser source for gas analysis applications.…”

“…This crystal has phase-matchable birefringence, good mechanical properties and a high optical damage threshold. The efficiency of the sum frequency generation of a low-pressure DC discharge CO laser radiation in ZnGeP 2 was demonstrated to range from 6.5%-10% [4,5], while in AgGaSe 2 , GaSe, and PbIn 6 Te 10 crystals it was 1% [6], 0.3% [7] and 0.01% [8], respectively (under similar experimental conditions).…”

“…All previous studies of frequency conversion of CO laser radiation in nonlinear crystals were made with long-size lowpressure DC discharge CO lasers [5][6][7][8] and a fairly large high-power nanosecond CO laser system [9,10]. However, a slab RF discharge CO laser is far more compact and has several advantages, such as pulse-periodic running, low-voltage power supply, the feasibility of pumping a large active volume at gas pressure of several tens or even up to 1000 Torr [12] without any external ionizing sources.…”

Numerical analysis of СО laser frequency conversion efficiency in BaGa2GeSe6crystal

“…Therefore, the objective of this paper is estimation of BGGSe crystal efficiency with respect to ZnGeP 2 , GaSe, and AgGaSe 2 by means of frequency conversion simulation for CO-and CO 2 -laser radiation. The calculations under discussion demonstrated that broadband two-stage frequency conversion of multi-line COlaser is quite possible in a BGGSe crystal as well as in ZnGeP 2 [6] and AgGaSe 2 [7]. …”