Robust 5 W continuous-wave 355 nm laser by single-pass third harmonic generation in LBO crystals.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Continuous-wave (CW) lasers are essential for various industrial applications.
• Third-harmonic generation (THG) is a key nonlinear optical process for generating shorter wavelengths.
• Lithium triborate (LBO) crystals are widely used for nonlinear frequency conversion.

Purpose of the Study:

• To develop a high-power, narrow-linewidth, continuous-wave 355 nm laser.
• To investigate phase-matching techniques for efficient third-harmonic generation.
• To assess the performance and potential applications of the developed laser system.

Main Methods:

• Single-pass third-harmonic generation (THG) of a fiber laser in two LBO crystals.
• Investigation of both type I and type II critical phase-matching (PM) in LBO for sum-frequency generation.
• Characterization of output power, power stability, and relative intensity noise.

Main Results:

• A maximum output power of 5 W was achieved using a type-I critical phase-matching LBO crystal.
• A single-pass conversion efficiency of 1.7% from 1064 nm to 355 nm was obtained.
• The relative intensity noise was below -110 dB/Hz for frequencies above 200 Hz, with 0.73% power stability.

Conclusions:

• A robust and compact single-pass THG laser system at 355 nm was successfully demonstrated.
• The laser system exhibits high power, good stability, and low noise, making it suitable for demanding applications.
• The developed laser has significant potential for applications in semiconductor manufacturing and inspection.