Optical properties of Nd:KGW crystal in the range of 0.2–2.1 THz

Abstract

We study optical properties of 1% Nd-doped KGW crystal by terahertz time-domain spectroscopy in the range of 0.2–2.1 THz. We find dispersion of the measured refractive indices in the studied frequency range. Their values for the three optical axes are ng = 3.75, nm = 3.37, np = 3.40 at 1 THz indicating the birefringence of Δn = ng – nm ≈ 0.38. We observe an increasing absorption for all three axes with dichroism up to 20 cm−1 at 2 THz. We attribute the main source of the dispersion and increasing absorption to phonon oscillations at 2.58 and 2.7 THz outside of the studied frequency range.

Keywords

• Terahertz spectroscopy
• Refractive index
• Absorption coefficient
• Birefringence
• KGW
• Nonlinear crystal