Simultaneous broadband Raman cascading and parametric conversion in potassium titanyl phosphate

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Stimulated Raman scattering (SRS) is a key nonlinear optical process for generating new frequencies.
• Cascaded SRS can produce a broad spectrum of light, but controlling spatial properties is challenging.
• Second-harmonic generation (SHG) and sum-frequency mixing (SFM) are vital for frequency conversion.

Purpose of the Study:

• To generate a broad infrared light spectrum using cascaded SRS in a potassium titanyl phosphate (KTP) crystal.
• To simultaneously achieve broadband visible light conversion via SHG and SFM.
• To investigate the spatial characteristics and nonlinear conversion efficiencies of the generated light.

Main Methods:

• Utilized a potassium titanyl phosphate (KTP) crystal to induce cascaded stimulated Raman scattering.
• Employed second-harmonic generation (SHG) and sum-frequency mixing (SFM) for broadband visible light conversion.
• Analyzed the spatial distribution and angular separation of generated Stokes components.

Main Results:

• Generated a broad spectrum of infrared light (1064-1300 nm) via cascaded SRS.
• Observed spatial separation of odd- and even-order Stokes components at different propagation angles.
• Reported significant spatial distortions in the output Stokes beams and discussed SHG/SFM efficiency dependence on pump polarization.

Conclusions:

• Demonstrated efficient generation of a broadband infrared spectrum and its subsequent visible conversion in KTP.
• Highlighted the spatial addressing of different order Stokes components, offering potential for beam steering.
• Identified spatial distortions as a key factor influencing nonlinear conversion processes.