A simplified scheme for generating narrow-band mid-ultraviolet laser radiation

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Science and Photonics
• Spectroscopy

Background:

• Developing continuous, narrow-band, and tunable laser sources in the mid-ultraviolet (UV) spectral region is crucial for high-precision spectroscopy.
• Direct frequency conversion methods offer efficient routes to generate UV light from readily available laser diodes.

Purpose of the Study:

• To report the development and characterization of novel laser systems for mid-UV generation.
• To demonstrate the capability of these systems for high-resolution spectroscopic measurements.
• To achieve stable frequency locking to atomic transitions.

Main Methods:

• Utilized direct second-harmonic generation (SHG) from blue and green diode lasers.
• Characterized the output power, spectral bandwidth, and tunability of the generated mid-UV laser systems.
• Employed Doppler-free saturation spectroscopy to probe the mercury 6(1)S0 → 6(3)P1 intercombination line at 253.7 nm.
• Implemented a frequency stabilization technique to lock the laser to the atomic transition.

Main Results:

• Achieved continuous, narrow-band, and tunable laser output in the mid-UV with power levels up to 11.1 mW.
• Successfully tuned the laser system to the 253.7 nm mercury intercombination line.
• Demonstrated Doppler-free saturation spectroscopy on the target transition.
• Attained long-term frequency locking of the laser to the mercury transition.

Conclusions:

• The developed laser systems provide a robust and efficient source for mid-UV generation.
• Direct SHG from diode lasers is a viable method for producing tunable, narrow-band UV light.
• The capability for precise spectroscopy and long-term frequency stabilization opens avenues for advanced metrology and fundamental physics research.