Temperature-tunable UV generation using an Alexandrite laser and PPLN waveguides.

Area of Science:

• Laser Physics and Photonics
• Nonlinear Optics
• Materials Science

Background:

• Continuous-wave (CW) tunable ultraviolet (UV) laser sources are crucial for various scientific applications.
• Existing methods for UV generation often involve complex setups or lack tunability.
• Alexandrite lasers offer near-infrared (NIR) tunability, but direct UV generation is challenging.

Purpose of the Study:

• To demonstrate a simple and novel technique for achieving wavelength-tunable CW UV laser operation.
• To explore the use of periodically-poled lithium niobate (PPLN) for second-harmonic generation (SHG) in the UV range.
• To assess the potential of this method for generating UV light between 360-400 nm.

Main Methods:

• Utilized a compact two-mirror Alexandrite laser cavity for NIR wavelength-tunable operation via temperature tuning.
• Employed temperature tuning of a periodically-poled lithium niobate (PPLN) waveguide for second-harmonic generation (SHG) to the UV.
• Investigated a third-order PPLN grating with a period (Λ) of 6.1 μm for efficient UV conversion.

Main Results:

• Achieved wavelength-tunable NIR operation from the Alexandrite laser crystal through temperature control.
• Generated UV light in two distinct tunable ranges: 376-379 nm and 384-386 nm, via SHG in the PPLN waveguide.
• Obtained a maximum UV power of 1.3 mW with 185 mW of NIR pump throughput, demonstrating efficient conversion.

Conclusions:

• The presented technique offers a simple and effective method for generating tunable CW UV laser light.
• The combination of a tunable Alexandrite laser and PPLN SHG provides access to the desired 360-400 nm wavelength range.
• This approach shows significant promise for developing practical and versatile UV light sources for diverse applications.