Difference frequency generation in AgGaS_2: Sellmeier and temperature-dispersion equations

Abstract

Two single-mode diode lasers and AgGaS(2) as a nonlinear medium are applied for difference frequency generation (DFG) in the mid-infrared spectral range between 4.9 and 6.5 mum. Phase matching is achieved by either temperature tuning or angle tuning of the crystal. Experimentally measured sets of input wavelengths lambda(s) and lambda(p), the resulting DFG wavelength lambda(i), and corresponding phase-matching temperatures or angles are compared with the calculated values derived by use of different Sellmeier equations and coefficients and temperature-dispersion equations dn/dT. Our results show that only specific combinations of previously published Sellmeier equations, coefficients, and temperature-dispersion equations are suitable for exact calculations of phase-matching parameters. These combinations reproduce our experimentally obtained phase-matching temperatures and angles with an accuracy of better than 5% and are therefore of fundamental interest for the design of a mid-infrared DFG spectrometer with AgGaS(2) as a nonlinear medium.

Synthesis, Structure and Bonding, Optical Properties of Ba4MTrQ6 (M=Cu, Ag; Tr=Ga, In; Q=S, Se)

“…Thus, an equal occupation between monovalent Ag (or Cu) and trivalent Ga (or In) can exactly fit the precise requirements of the electrons. Such a mixing can be further supported by the corresponding interatomic distances ( Table 3): for example, the Ag/ GaÀS bonds fall into a medium distance range of approximately 2.4049(18)-2.4927 (14) ; these bonds are evidently longer than the sole GaÀS pairs such as those in AgGaS 2 and Ba 23 Ga 8 Sb 2 S 38 , [1,15] but they are shorter than the typical Ag À S bonds in Ba 2 AgInS 4 . [36] The sites occupied by a mixture of Ag (or Cu) and Ga (or In) are coordinated by four chalcogen atoms, and the resulting tetrahedra are further connected in a corner-sharing fashion to build 1D chains parallel to the direction of the b axis ( Figure 3).…”

“…Among them, important nonlinear optical and photovoltaic materials have been frequently reported for ternary phases such as AgGaQ 2 , LiInQ 2 , LiGaQ 2 , BaGa 4 Q 7 , and CuInQ 2 (Q = S, Se). [1][2][3][4][5][6][7][8][9][10] Most of these chalcogenides are based on metal chalcogenide tetrahedra interconnected in a corner-or edge-sharing manner. In recent years, systematic research efforts in this area have resulted in the extension of these systems to include group 14 and 15 metals as well as some transition metals.…”

Mid-infrared laser-tomographic imaging of carbon monoxide in laminar flames by difference frequency generation

“…Phase-matching conditions and, thus, the obtained MIR output power and the spectrometer's sensitivity were affected by jittering of the pump and signals wavelengths, as well as the alignment of the nonlinear crystal and the beam shaping optics, as discussed quantitatively elsewhere [20]. …”

“…Nevertheless, for combustion diagnostics the detection of CO and NO, which show fundamental absorption at ∼ 4.9 and 5.1 µm, respectively, is very important. Therefore, in the present investigation, DFG in silver thiogallate (AgGaS 2 ), applying two singlemode NIR diode lasers as pump and signal sources, was used to setup a tunable narrow-bandwidth laser system in the spectral range at ∼ 5 µm operating at room temperature [20]. Despite the apparently low optical output power achievable by DFG laser sources, the technology provides high sensitivity and selectivity.…”

Picosecond mid-infrared LIDAR system

“…Difference frequency generation in penodically poled LiNbO3 is a powerful tool for the generation of widely tunable and narrow bandwidth mid-infrared laser radiation [2]. An Yb-fiber amplified passively Q-switched Cr4+:Nd3+:YAG microchiplaser is used as a pulsed signal source while the pump source is a cw laser diode which is amplified by a tapered amplifier.…”