George L. Fischer

Z-scan measurement technique for non-Gaussian beams and arbitrary sample thicknesses

We demonstrate a new Z-scan measurement technique that permits the use of non-Gaussian beams and thick, as well as thin, samples. We expect that this technique will make possible the measurement of optical nonlinearities by the use of lasers that previously would have been unsuitable for this purpose, because of either inadequate beam quality or inadequate power. Another advantage of this technique is that it does not require detailed knowledge of the temporal characteristics of the laser pulse that is used.

NONLINEAR-OPTICAL CHRISTIANSEN FILTER AS AN OPTICAL POWER LIMITER

We have constructed an optical power limiter based on nonlinear induced scattering in a cell containing crushed glass and a mixture of acetone and carbon disulfide. For 30-ps-long laser pulses the transmitted energy saturates at a value of 6 microJ. We also present the results of a theoretical modeling study that shows how the operating characteristics of such a device can be optimized.

Measurement of the power distribution during stimulated brillouin scattering with focused gaussian beams

Abstract We show both theoretically and experimentally that, when stimulated Brillouin scattering (SBS) is produced using focused Gaussian beams, the spatial extent of the pump depletion region changes significantly with the input power. We also show that the location of the SBS interaction region depends on the ratio of the input power to the SBS threshold power. Only below and near SBS threshold is the interaction region largely located within several confocal parameters of the beam waist, as is often assumed in simplified treatments of the SBS process.

Enhancement of the uniformity and rotation of large aperture, permanent magnet, tunable Faraday rotators

Abstract We present new methods for increasing the magnitude and uniformity of rotation of a Faraday rotator with a large clear aperture. We show theoretically and experimentally that the amount of rotation and the uniformity of rotation across the aperture can be simultaneously increased by introducing a small separation between adjacent, oppositely oriented magnets. Furthermore we show that the uniformity can be increased by displacing the rod of rotator glass longitudinally from the centred position. We have constructed such a device and obtained an isolation ratio of 45 dB at 1·06 μm.

Nonlinear optical properties of thin film composite materials

Several groups have proposed the use of composite materials as a means of achieving large values of the third-order susceptibility /spl chi//sup (3/). One proposal involves forming a composite of alternating layers of two different materials with layer thicknesses much smaller than an optical wavelength. The angular dependence of the nonlinear optical response of this material can offer a means to determine quantitatively the extent to which the /spl chi/((3)) susceptibility is enhanced. In the present paper, we report the results of our experimental study of this angular dependence. We find that the angular dependence is in good qualitative agreement with theoretical predictions.<<ETX>>