All-solid-state single-frequency 248-nm DUV source based on compact collinear cascaded sum frequency mixing scheme

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Deep ultraviolet (DUV) light sources are crucial for various scientific and industrial applications.
• Traditional DUV generation methods often involve complex setups or less efficient processes.
• All-solid-state sources offer advantages in terms of stability, compactness, and reliability.

Purpose of the Study:

• To demonstrate an all-solid-state 248-nm DUV source using a collinear cascaded sum frequency generation (SFG) scheme.
• To investigate and compare the performance of type-I and type-II phase-matched BBO crystals for SFG at 248 nm.
• To achieve efficient DUV generation without the need for a time delay line.

Main Methods:

• Utilized a 355-nm pumped optical parametric oscillator (OPO) to generate an 827-nm idler beam.
• Combined the 827-nm idler and residual 355-nm pump in a collinear cascaded BBO crystal for SFG.
• Employed both type-I and type-II phase-matched BBO crystals for SFG and compared their output characteristics.

Main Results:

• Achieved a 248-nm DUV source with a linewidth of ~450 MHz, pulse width of ~4 ns, and central wavelength of 248.1 nm.
• Type-I SFG yielded an output power of 123.4 mW with beam quality factors M_x^2 = 2.86 and M_y^2 = 2.80.
• Type-II SFG produced 34.6 mW output power but with improved beam quality (M_x^2 = 1.21, M_y^2 = 1.18) due to nonlinear coefficients and phase-matching conditions.

Conclusions:

• Successfully demonstrated a compact, all-solid-state 248-nm DUV source via collinear cascaded SFG.
• Type-I phase-matching offers higher output power, while type-II provides superior beam quality for the 248-nm DUV generation.
• The collinear cascaded SFG scheme is an effective approach for generating DUV radiation without time delay lines.