Continuous-wave single-frequency 295 nm laser source by a frequency-quadrupled optically pumped semiconductor laser.

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Nonlinear Optics

Background:

• Optically pumped semiconductor lasers (OPSLs) offer tunable, high-power output.
• Generating ultraviolet (UV) light efficiently remains a challenge.
• Frequency conversion techniques are crucial for accessing shorter wavelengths.

Purpose of the Study:

• To develop a compact and efficient source for single-frequency ultraviolet (UV) light at 295 nm.
• To explore the potential of frequency quadrupling in semiconductor laser systems.
• To investigate the use of external resonators for enhanced nonlinear frequency conversion.

Main Methods:

• Utilized a highly strained Indium Gallium Arsenide (InGaAs) quantum-well semiconductor laser operating at 1178 nm.
• Employed intracavity frequency doubling to achieve 589 nm output.
• Implemented an external resonator with beta-Barium Borate (BBO) crystal for second harmonic generation to reach 295 nm.

Main Results:

• Achieved up to 136 mW of continuous-wave (cw) single-frequency output power at 295 nm.
• Demonstrated stable single-frequency operation of the InGaAs semiconductor laser at 1178 nm.
• Successfully converted the 589 nm intracavity-doubled output to the target 295 nm UV wavelength.

Conclusions:

• Frequency quadrupling of an optically pumped semiconductor laser is a viable method for generating UV light.
• The developed system provides a powerful and compact source for 295 nm radiation.
• This technology has potential applications in spectroscopy, photochemistry, and biomedical imaging.