All solid-state single-frequency DUV source at 248 nm

Area of Science:

• Optics and Photonics
• Laser Physics
• Nonlinear Optics

Background:

• Development of compact and efficient deep ultraviolet (DUV) laser sources is crucial for various scientific and industrial applications.
• Existing DUV sources often face limitations in terms of size, robustness, or spectral purity.
• Solid-state laser technology offers advantages over traditional gas lasers for DUV generation.

Purpose of the Study:

• To realize an all solid-state single-frequency 248 nm pulsed DUV source.
• To achieve high beam quality and coherence from the DUV source.
• To establish a compact and robust DUV generation method using readily available fundamental laser drivers.

Main Methods:

• Multi-stage nonlinear frequency conversion of a 1064 nm fundamental laser driver.
• Generation of a 355 nm third harmonic wave and an 827 nm signal wave from an optical parametric oscillator (OPO).
• Sum-frequency generation (SFG) combining the 355 nm and 827 nm sources to produce 248 nm DUV radiation.

Main Results:

• Achieved an average power of approximately 120 mW at a 4 kHz repetition rate.
• Obtained a pulse width of 4.8 ns with a beam quality factor (M^2) less than 1.5.
• Estimated linewidth of approximately 250 MHz, indicating single-frequency operation.

Conclusions:

• A compact, robust, and efficient all solid-state 248 nm DUV source was successfully demonstrated.
• The developed DUV source utilizes multi-stage nonlinear frequency conversion from a single 1064 nm driver.
• The 248 nm DUV source is suitable as a seed for KrF excimer laser amplifiers, enhancing beam quality and coherence.