High frequency-reproducibility nanosecond pulsed laser with high output power

Area of Science:

• Laser Physics
• Nonlinear Optics
• Optical Engineering

Background:

• Achieving high-power, single-longitudinal-mode (SLM) pulsed lasers with excellent frequency reproducibility is crucial for various scientific applications.
• Existing methods often struggle to balance high power with precise spectral control and inter-pulse consistency.

Purpose of the Study:

• To develop a novel method for enhancing the frequency reproducibility and spectral purity of high-power SLM pulsed lasers.
• To investigate the combined effects of nonlinear optical frequency conversion (NOFC), pre-lasing, and etalon filtering on laser performance.

Main Methods:

• Implemented a type-I phase-matched Lithium Triborate (LBO) crystal for NOFC to increase mode selectivity.
• Introduced a pre-lasing process by optimizing Q-switch loss to boost dominant mode intensity.
• Incorporated an etalon set with varying thicknesses (0.5 mm, 1 mm, 10 mm) for precise frequency selection within the laser resonator.

Main Results:

• Successfully narrowed the spectral width of the 1064 nm laser from 32.80 pm to 14.40 pm using NOFC and pre-lasing.
• Significantly improved wavelength drift from <1.20 pm to <0.36 pm.
• Further reduced spectral width to 2.20 pm and wavelength drift to <0.07 pm by employing the etalon set, demonstrating high frequency reproducibility.

Conclusions:

• The combined approach of NOFC, pre-lasing, and etalon filtering effectively enhances frequency reproducibility and spectral purity in high-power SLM pulsed lasers.
• This technique offers a robust solution for applications demanding highly stable and spectrally narrow laser outputs.
• The demonstrated improvements in spectral width and wavelength drift pave the way for advanced laser system designs.