Remarkable temperature-dependent second-harmonic-generation performance of a YCOB crystal

Area of Science:

• Nonlinear Optics
• Materials Science

Background:

• Second-harmonic-generation (SHG) is crucial for frequency conversion in lasers.
• Temperature stability of nonlinear optical crystals is a key parameter for practical applications.

Purpose of the Study:

• To investigate the temperature stability of SHG in YCa4O(BO3)3 (YCOB) crystals across a wide temperature range (-10 to 520 °C).
• To identify the optimal phase-matching (PM) conditions for temperature-insensitive SHG in YCOB.
• To evaluate YCOB as a potential material for high-temperature, stable SHG applications.

Main Methods:

• Theoretical calculations and experimental measurements were employed to determine SHG properties.
• The temperature stability of the phase-matching angle was analyzed.
• The temperature bandwidth of SHG was experimentally measured for a YCOB crystal cut along the optimal PM direction.

Main Results:

• An optimal phase-matching direction for YCOB was identified at (θ = 149.2°, ϕ = 0°) within the XZ principle plane.
• A unique regression phenomenon of the PM angle was observed, enhancing SHG output at temperatures above 200 °C.
• A YCOB crystal cut along the optimal direction demonstrated a temperature bandwidth exceeding 490 °C·cm for Nd:YAG laser SHG.

Conclusions:

• YCOB crystals offer exceptional temperature stability for SHG.
• The identified optimal cut provides a significant advantage for applications requiring temperature-insensitive frequency conversion.
• YCOB is a leading candidate among nonlinear optical crystals for demanding, high-temperature SHG applications.