Broad-band squeezed states of light are generated by forward nondegenerate four-wave mixing in a single-mode optical fiber cooled below 4.2 K. The minimum total noise level was (12.5 ±0.5)% below the standard quantum limit.

Performance degradation in liquid crystal cells was studied by analyzing the time evolution of optical and integrated current vs voltage hysteresis curves as test cells were subjected to a dc bias. We find evidence for permanent increases in liquid crystal mobile ion populations, the primary cause of device performance degradation, and suggest this permanent increase is due to selective adsorption by the alignment layers of ions of a single charge sign combined with the presence of a neutral ionizable species in the liquid crystal.

Nondegenerate four-wave mixing in an optical fiber is shown to attenuate one quadrature of random sideband fluctuations created by external modulators. A theory of the nonlinear interaction that includes nonlinear dispersion fits the results. Analogous experiments on quantum noise inputs should prove successful.

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The centroid of a single-transverse-mode laser beam fluctuates in position because of spontaneous emission of the laser medium into higher transverse cavity modes.

Polarized and depolarized components of the quasielastic light-scattering spectrum of fused-silica optical fiber have been measured in the frequency range 100 kHz to 100 MHz at temperatures from 10 to 293 K. The depolarization ratio was found to be 0. 14+0.03. In the backscattering geometry both polarization components are seen to obey an inverse-power-law frequency dependence. Both the temperature and frequency dependence are consistent with a model that assumes thermal activation of structural relaxations which have a wide distribution of relaxation-time constants. In the forward direction, an additional polarized component with the same temperature dependence appeared.

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