Multi-color switchable visible light source generated via nonlinear frequency conversion of a random fiber laser

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Nonlinear frequency conversion of random fiber lasers enables flexible visible and mid-infrared light generation.
• Previous methods for random fiber lasers produced single-color visible light via frequency doubling.

Purpose of the Study:

• To propose and demonstrate a novel multi-color switchable visible light source.
• To utilize a dual-wavelength switchable random Raman fiber laser (RRFL) for generating switchable visible light.

Main Methods:

• Developed a dual-wavelength switchable RRFL using phosphosilicate fiber, leveraging distinct Raman gain peaks.
• Employed a periodically poled lithium niobate (PPLN) crystal array for second-harmonic generation (SHG) and sum-frequency generation (SFG).
• Precisely tuned pump wavelength to control Raman gain and achieve switchable lasing at 1120 nm and 1238 nm.

Main Results:

• Achieved switchable dual-wavelength lasing at 1120 nm and 1238 nm with 3-watt level output power and sub-1 nm bandwidth.
• Demonstrated switchable visible light output of green (560 nm), yellow (588 nm), and red (619 nm) light via nonlinear frequency conversion.
• Obtained optical powers of 22.2 mW (green), 16.9 mW (yellow), and 18.5 mW (red).

Conclusions:

• The dual-wavelength RRFL serves as a versatile platform for generating flexible multi-color visible light.
• This technology holds potential for applications in advanced imaging, sensing, and optical metrology.
• Further improvements in output power and spectral bandwidth are achievable with optimized laser design.