Tunable stimulated Raman scattering by pumping with Bessel beams

Area of Science:

• Nonlinear Optics
• Laser Physics
• Condensed Matter Physics

Background:

• Stimulated Raman scattering (SRS) is a vital nonlinear optical process for generating new frequencies.
• Traditional SRS methods often face limitations in beam quality and tunability.
• Bessel beams offer unique propagation-invariant properties with potential applications in nonlinear optics.

Purpose of the Study:

• To introduce and investigate a novel pumping scheme for SRS utilizing a Bessel beam.
• To explore the generation mechanism of the Stokes beam in this new configuration.
• To demonstrate the tunability of SRS from polaritons using the Bessel beam geometry.

Main Methods:

• Implementation of a Bessel beam for pumping stimulated Raman scattering.
• Experimental SRS generation from molecular vibrations in acetone.
• Experimental SRS generation from a polariton mode in lithium iodate (LiIO(3)).
• Analysis of the generated Stokes beam characteristics and propagation.
• Investigation of the Stokes beam generation mechanism through component plane wave scattering.

Main Results:

• A nearly diffraction-limited Stokes beam was successfully generated along the Bessel beam's cone axis.
• The generation mechanism was identified as noncollinear scattering from the Bessel beam's constituent plane waves.
• Tunable frequency generation of SRS from polaritons in LiIO(3) was achieved by altering the Bessel beam's cone angle.

Conclusions:

• The Bessel beam pumping scheme provides an effective method for generating high-quality Stokes beams in SRS.
• This approach offers a new route for tunable frequency generation, particularly from polaritonic excitations.
• The findings open possibilities for advanced spectroscopic techniques and light sources.