Total Reflection Phenomena in Second-Harmonic Generation of Light

TLDR

Second-harmonic beam direction, polarization, and intensity in NaClO3 were measured versus incidence angle for a laser incident from a denser fluid. Below the critical angle a reflected harmonic and two oppositely polarized transmitted beams appear, and between the fundamental and second-harmonic critical angles total reflection occurs but one transmitted beam persists, and above the second-harmonic critical angle only the reflected beam remains, and when two counter‑propagating beams are incident second‑harmonic radiation emerges in both normal directions, all matching Bloembergen and Pershan theory.

Abstract

The direction, polarization, and intensity of second-harmonic light beams generated in a crystal of NaCl${\mathrm{O}}_{3}$ have been observed as a function of the angle of incidence, when the primary laser beam is incident from a denser linear fluid. When the angle of incidence ${\ensuremath{\theta}}_{i}$ is smaller than the critical angle for total reflection ${\ensuremath{\theta}}_{\mathrm{crit}}(\ensuremath{\omega})$, a reflected harmonic beam and two distinct spatially resolved transmitted harmonic beams with polarizations precessing in opposite senses are observed. When ${\ensuremath{\theta}}_{\mathrm{crit}}(2\ensuremath{\omega})>{\ensuremath{\theta}}_{i}>{\ensuremath{\theta}}_{\mathrm{crit}}(\ensuremath{\omega})$, the incident laser power is totally reflected, but one of the transmitted harmonic beams still exists. For ${\ensuremath{\theta}}_{i}>{\ensuremath{\theta}}_{\mathrm{crit}}(2\ensuremath{\omega})$, only the reflected harmonic beam remains. When two totally reflected laser beams are incident from opposite sides of the normal, second-harmonic radiation occurs in the direction of both the inward and outward normal. The results agree quantitatively with the theory of Bloembergen and Pershan.