Octave-spanning supercontinuum generation from off-axis Raman oscillation in a monolithic KTP crystal

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Supercontinuum generation is crucial for various applications, including spectroscopy and optical communications.
• Traditional supercontinuum sources often rely on complex fiber-optic setups or bulky laser systems.
• Developing compact, efficient, and broadband light sources remains an active area of research.

Purpose of the Study:

• To demonstrate a novel, mirrorless Raman oscillator for generating broadband visible and near-infrared supercontinuum.
• To investigate the underlying physical mechanisms of supercontinuum generation in a monolithic KTP crystal.
• To achieve octave-spanning spectral bandwidth from a compact laser system.

Main Methods:

• Utilized a monolithic potassium titanyl phosphate (KTP) crystal as a Raman gain medium.
• Employed a Q-switched Nd:YAG laser as the pump source.
• Leveraged total internal reflection (TIR) and off-axis Stokes wave trapping for enhanced Raman gain and spectral broadening.

Main Results:

• Generated a visible and near-infrared supercontinuum spanning from 540 nm to 1800 nm.
• Achieved quasi-mode-locked Stokes pulses due to the oscillator's design.
• Demonstrated maximization of Raman gain with specific polarization configurations.

Conclusions:

• The monolithic mirrorless Raman oscillator in KTP is a viable and compact source for broadband supercontinuum generation.
• The demonstrated approach offers a promising alternative to conventional supercontinuum generation techniques.
• Further research could explore different crystal materials and pump sources for tailored spectral outputs.