Nonlinear Optical Crystals: A Complete Survey

A simple model for evaluation of refractive indices of some binary and ternary mixed crystals

A method that uses improved mathematical forms and data-processing techniques has been developed for generating index dispersion equations for nonlinear optical crystals. The data may be diverse, including measured indices of refraction, type I, II, or III critically phase-matched angles, noncritically phase-matched wavelengths, non-phase-matched coherence lengths, isoindex wavelengths, and optical retrace wavelengths and angles. The method automatically estimates and compensates for heretofore unknown crystal orientation errors, attributed principally to manufacturing inaccuracies. In the examples given here, 13-parameter fits to refractive indices n(o) and n(e) are required to reconcile literature data(0.49-12 μm) for AgGaS(2), whereas ten-parameter fits are required for KDP (0.18-1.5 μm) and AgGaSe(2) (0.8-15.5 μm). These examples demonstrate improvements in precision over a wider wavelength range than those for previously calculated refractive indices and critically phase-matched angles, as well as non-critically phase-matched and isoindex wavelengths.

Dispersion equations for nonlinear optical crystals: KDP, AgGaSe(2), and AgGaS(2).

The electronic structure of modified CuGaS2, which belongs to the family of Cu-containing chalcopyrites, has been analyzed from first principles within the density functional theory. The chalcopyrite matrix has been modified by introducing a high concentration of atomic impurities that included transition metals and elements of group IVa at substitutional sites of the lattice host. For selected cases, an intermediate band has been found that potentially fulfills the requirements as stated for intermediate-band solar cell materials. Preliminary thermochemical estimations of the stability of the compounds proposed against eventual secondary phases in the form of binary chalcogenides have greatly simplified the general screening. Elements of groups VIIIb and IVa have been identified as interesting impurity candidates to obtain intermediate bands within the main gap of the modified ternary host. Additionally, modified chalcopyrite compounds with potential applications as magnetic semiconductors or spintronic ...

Analysis of the Electronic Structure of Modified CuGaS2 with Selected Substitutional Impurities: Prospects for Intermediate-Band Thin-Film Solar Cells Based on Cu-Containing Chalcopyrites

We demonstrate a novel traveling-wave-type optical parametric generator based on 1.25‐µm pumping of HgGa2S4 that produces tunable, high-power, transform-limited ∝200‐fs pulses in the mid-IR from 5 to 9 µm. Output idler energies on the microjoule level are obtained with maximum conversion efficiency of 11% for the amplifier stage, which is more than two times better than the results obtained with an analogous sample of the widely spread material AgGaS2.

Mercury thiogallate mid-infrared femtosecond optical parametric generator pumped at 1.25 µm by a Cr:forsterite regenerative amplifier

An investigation was made of the phase diagram of the Hgs–HgGa2S4 system. It was shown that there is a region of HgGa2S4-based solid solutions. Optically homogeneous mercury thiogallate single crystals were grown and used to measure the refractive indices in the 0.55–11 μ range. A phase-matching diagram was plotted for an o + o→e frequency mixing process. This diagram confirmed phase-matched interaction in the specified wave-length range.

http://iopscience.iop.org/article/10.1070/QE1979v009n08ABEH009420/pdf

Growth and optical properties of mercury thiogallate

Homogeneous single crystals of mercury thiogallate HgGa2S4 were grown. Their diameter and length were 12 mm and 40 mm, respectively; the absorption coefficient was of the order of 0.1 cm−1. The nonlinear susceptibility coefficients d36(HgGa2S4) = 1.8d36(AgGaS2) and d31(HgGa2S4) = 0.6d36(AgGaS2) were determined.

Growth and nonlinear properties of HgGa2S4

A study was made of the growth conditions for the AgGa1–xInxS2 system and single crystals with the compositions x = 0.08, 0.2 and 0.6 were grown. The absorption coefficients and the refractive indices were measured in the range 0.55–11.5 μ. The wavelength dependences of the refractive indices were approximated by the Sellmeier polynomials. The phase matching diagrams were plotted for the oo-e frequency mixing process. A study was made of the influence of the percentage amounts of gallium and indium in these single crystals on the phase-matching conditions.

http://iopscience.iop.org/article/10.1070/QE1980v010n10ABEH010582/pdf

Growth and optical properties of the AgGa1–xInxS2 system

Calculations were made of the characteristics of a CO2 laser radiation converter utilizing a mercury thiogallate (HgGa2S4) crystal pumped by YAG laser radiation. The measured conversion efficiency was 60%. The experimental results were compared with the theoretical calculations of the geometry and conversion efficiency. The stability of HgGa2S4, crystals with respect to near and middle infrared radiation was estimated.

Frequency up-conversion in a mercury thiogallate crystal

An optical polarization filter was constructed from a CdGa2S4 single crystal. This filter was temperature-tunable in the range 487–580 nm. Its pass band was 2 nm and the transmission at the maximum of the spectral characteristic was 48%. The filter was also capable of withstanding high-power laser radiation (damage threshold 32 MW/cm2).

S M Pshenichnikov

Papers

Growth and optical properties of mercury thiogallate

Growth and nonlinear properties of HgGa2S4

Growth and optical properties of the AgGa1–xInxS2 system

Frequency up-conversion in a mercury thiogallate crystal

Narrow-band tunable optical filter made of a CdGa2S4 single crystal