Statistical Fluctuations in Nonlinear Optical Processes

TLDR

Momentum‑space limitations require a separate discussion of light‑beat creation at small difference frequencies. The study examines how partial coherence in a laser beam affects nonlinear optical interactions. The analysis includes mixing and higher‑harmonics generation. Experiments with a Q‑switched ruby show that random amplitude and phase modes cause fluctuations in second‑harmonic production and errors in measuring the nonlinear constant.

Abstract

The influence of partial coherence in a laser beam on nonlinear optical interactions is discussed. The presence of several different modes with random amplitude and phases is shown to lead to fluctuations in second-harmonic production and to an error in the measurement of the corresponding nonlinear constant. Experiments have been carried out with a "$Q$-switched" ruby, which demonstrate the role of partial spatial coherence in creating fluctuations in second-harmonic production. Mixing and higher harmonics generation are also considered. Limitations in momentum space necessitate a separate discussion of the creation of light beats at small difference frequencies.