Intensity Dependent Reflection Research Articles

Analysis of a high-resolution and large-dynamic-range spatial filter using a pair of facing phase conjugators with gains

We propose and analyze a complex-amplitude spatial filter consisting of a pair of facing phase conjugators with gains that have the special features of a large dynamic range and a high spatial resolution. We show analytically that the high resolution is maintained even if the imaging lenses inserted have large aberrations. The large-dynamic-range characteristics are evaluated numerically, taking into account the intensity-dependent nonlinear reflectivity of the phase conjugators, showing that the maximum intensity of the input wave allowed decreases with the increasing dynamic range required. Some consideration is also given to the design of the spatial filter.

Probe-beam intensity-dependent reflectivity in degenerate four-wave mixing in a saturable absorber

A degenerate four-wave mixing experiment is performed in the saturable absorber of cryptocyanine. When the pump-beam intensity is below the saturation intensity, the reflectivity of the probe beam does not change, even though the probe-beam intensity is increased; however, the reflectivity begins to decrease slowly for moderate pump-beam intensity and finally decreases as l/q (q is the ratio of probe-to-forward pump-beam intensity) for pump-beam intensity far above the saturation intensity. The results are explained by extending Kogelnik's coupled-wave theory of volume grating to the four-wave case.

Theory of continuous-flow amplifiers and resonators

An analysis is made of the influence of overlap of optical beams on the performance of optical amplifiers and resonators. Complete analytic solutions are obtained for single- and double-pass amplifiers, and also for a resonator having mirrors with an intensity-dependent reflection coefficient. Simple equations are derived for their efficiencies.

Saturation of Stimulated Backscattered Radiation in Laser Plasmas

Measurements of the back reflection from laser-produced plasmas have been carried out for laser intensities of up to 1.5\ifmmode\times\else\texttimes\fi{}${10}^{16}$ W/${\mathrm{cm}}^{2}$ with pulse durations of 120 psec using spherical low-$Z$ targets. The reflectivity of the plasma increases with incident intensity but saturates at a value of 10%. The intensity-dependent reflectivity is attributed to stimulated Brillouin scattering.