Difference frequency generation of 5–18 μm in a AgGaSe_2 crystal

Abstract

Mid-infrared radiation in the 5-18-mum range has been obtained by difference frequency generation in a AgGaSe(2) crystal by pumping with the output of a type I LiNbO(3) optical parametric oscillator (OPO). Here we suggest the use of a LiTaO(3) retarder to achieve an orthogonal state of polarization between OPO outputs that are necessary for efficient pumping of a AgGaSe(2) crystal. Several tens of kilowatts of peak power near 8 mum and continuously tunable operation in the above range have been obtained.

Difference frequency generation between the output waves of the PP-MgO:LN optical parametric oscillator

“…This value is smaller than those previously reported for experiments of DFG with OPO pumping [6,9]. The spectrum of the DFG radiation at 9.88 µm is presented in Fig.…”

“…Therefore, a special phase plate must be used to rotate polarization of one wave, but to leave the polarization of the other intact. We used calculations presented in [6] for such a phase plate and a 470 µm thick quartz plate was made which rotated the polarization of the idler wave by 90 degrees, but the polarization of the signal wave remained unchanged. This phase plate was optimized for the 2.5 µm wavelength, but we did not observe a significant decrease in its performance in the whole tuning range from 2.3 to 2.6 µm used in this work.…”

“…This approach has been successfully applied with bulk LN and KTP (KTiOPO 4 ) OPOs in AgGaSe 2 and AgGaS 2 crystals (see [5][6][7][8]). As far as periodically poled crystals are concerned, successful DFG in AgGaS 2 between PPLN OPO output waves was reported by Haidar et al [9].…”

En route to electrically pumped broadly tunable middle infrared lasers based on transition metal doped II–VI semiconductors

“…This work has included direct generation in semiconductors using InAsSbP/InAsSb/InAs [1] and quantum cascade lasers [2][3][4]. Mid-IR wavelengths have also been generated using nonlinearities in optical parametric oscillators (OPOs) and difference frequency generators (DFGs) [5][6][7]. All of these approaches yield tunable sources in the mid-IR.…”

“…Tunability over 400 nm between 2250 and 2650 nm was achieved [29,30]. (5) In an external cavity configuration a compact Er-fiber laser pumped broadly tunable over $700 nm between 2170 and 2840 nm CW RT Cr 2+ :ZnS laser was realized, yielding up to 700 mW at $40% slope efficiency [31,32]. (6) First multiline and ultrabroadband lasing of Cr 2+ :ZnSe in a spatially dispersive cavity has been realized [33].…”