Nonlinear optical coefficients and phase-matching conditions in Sn(2)P(2)S(6)

Area of Science:

• Materials Science
• Optics
• Crystallography

Background:

• Nonlinear optical (NLO) crystals are crucial for frequency conversion in lasers.
• Sn2P2S6 is a promising material for NLO applications, but its phase-matching properties require detailed investigation.

Purpose of the Study:

• To determine the second and third-order nonlinear optical coefficients of Sn2P2S6 crystals.
• To analyze phase-matching conditions for various nonlinear optical processes.
• To experimentally demonstrate phase-matched second harmonic generation (SHG).

Main Methods:

• Maker-Fringe technique for measuring nonlinear optical coefficients.
• Calculation of phase-matching conditions using refractive index data.
• Experimental demonstration of type I SHG at 1907 nm.

Main Results:

• Reported largest second harmonic generation (SHG) coefficients: d111 = 17±1.5 pm/V at 1542 nm and d111 = 12±1.5 pm/V at 1907 nm.
• Determined third-order susceptibilities chi(3) 1111 and chi(3) 2222 at 1907 nm.
• Demonstrated experimental phase-matched type I SHG at 1907 nm, consistent with theoretical predictions.

Conclusions:

• Sn2P2S6 exhibits significant nonlinear optical properties suitable for frequency conversion.
• Phase-matched optical parametric oscillation is feasible across the crystal's transparency range up to 8 micrometers.
• The material shows great potential for applications in tunable light sources and nonlinear optics.