Enhancement of the Kerr effect was studied to assess its effectiveness in improving readout characteristics of a magneto-optical memory utilizing MnBi films. SiO was used to enhance the Kerr effect by coating it on magnetic films. The coating results in a change, not only in the Kerr rotation but also in the ellipticity and reflectivity of the films. Changes of these quantities were calculated as a function of the SiO thickness, using optical constants of both MnBi and SiO, i.e., the refractive indices n2 and n3 of SiO and MnBi, respectively, and the off-diagonal element ε′ of the dielectric tensor of MnBi. The optical constants determined in this work were n2=(2.0±0.02)−(0.02±0.02)i, n3=3.1−3.5i, and ε′ = −1.2−0.4i at a wavelength of 6328 Å. The Kerr rotation and the reflectivity were measured for various SiO thicknesses and were compared with the results of theoretical calculations. Experimental and theoretical results agreed well with each other. The readout signal-to-noise ratio, which is a function of the Kerr rotation, ellipticity, and reflectivity, is expected to be improved by a factor of more than 2, when SiO is coated on the MnBi film surface.

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Low loss splicing of silica fibers by means of a 5-W CO(2) laser has been demonstrated. Step-index fibers with a core diameter of 56 microm and an outer diameter of 154 microm were fused together. The chopped laser beam, effectively 2.3 W and about 1.0 mm in beam-spot diameter, was moved across the fiber ends at a speed of 10 microm/sec. Ninety percent of twenty-one splices had losses less than 0.12 dB with a minimum loss of 0.02 dB. Good reproducibility of the low loss splice was achieved by contacting the fibers tightly before fusing them together.

Heat conduction in optical fibers during CO(2) laser splicing is analyzed, taking into account the Gaussian profile of the laser power density distribution. Expressions for temperature in optical fibers are derived as a function of time, position, and beam radius. The minimum required laser power is calculated for various beam radii and compared with the experimental results. Typical combinations of laser beam parameters required to achieve good splices of silica fibers with approximately 150-microm o.d. are 500-microm beam radius and 3-W beam power.

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