Degenerate Frequency Two Beam Coupling in Organic Media Via Phase Modulation

by Jonathan E. Slagle

Institution: University of Dayton
Department: Electro-Optics
Degree: MS(M.S.)
Year: 2014
Keywords: Optics; Physics; Electromagnetism; two beam coupling; degenerate frequency; self-phase modulation; nonlinear optics; organic media; irradiance scan; two wave mixing; nonlinear transmission
Record ID: 2042894
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417798867


The following research was born out of the observation of a counter-propagating beam (CPB) originating from the interaction of a pump beam and a Fresnel reflection inside an organic liquid held inside a fused silica cuvette. The strong influence on overlap with the Fresnel reflection is evidence for degenerate frequency two-beam coupling (TBC) via a transient phase grating. It is well known that TBC requires a phase shift between the fields and the induced grating which is supplied by the finite temporal response of the nonlinearity. TBC also requires a frequency shift between the interacting fields. For degenerate frequencies to couple, this shift must arise from self or cross phase modulation in the medium. In this work, we present a strong, degenerate frequency TBC in two organic systems using a single nanosecond beam where the probe is generated from the Fresnel reflection of the cuvette and the necessary phase and frequency shifts are the result of the thermo-optic effect and population redistribution. Its effect on the analysis of nonlinear transmission experiments and its relationship with Stimulated Rayleigh Bragg Scattering (SRBS) is also presented.