matrices have been used extensively to study the propagation of light in anisotropic layered systems whose principal optic axes have arbitrary orientation. We present a general theory for the propagation of light in arbitrarily anisotropic layered systems that is particularly suited for treating optical degeneracies that arise ͑1͒ when light propagates in an isotropic medium embedded within the anisotropic layers or ͑2͒ when light propagates along one of the optic axes in an anisotropic layer. Boundary conditions are applied explicitly to the electric and magnetic fields at each interface, and transfer matrices that relate the transmitted and reflected fields to the optical properties of the system are developed. Criteria are given for identifying the mathematical singularities caused by the degeneracies described above, and a method for treating the singularities in the relevant expressions is presented.

We have calculated the total critical current as a function of applied magnetic flux for a superconducting interferometer consisting of many Josephson junctions in parallel. An enhancement and narrowing of the periodic principal maxima in the critical current versus flux characteristic is predicted as the number of junctions in parallel increases, even when the effects of finite self- and mutual inductances and nonuniformity of the junction critical currents are included in the calculations. The possible application of the superconducting quantum interference grating, or SQUIG, for the detection of magnetic flux is discussed.

X-ray diffraction is shown to provide a direct, quantitative, structural measurement of the degree of spontaneous ordering in GaInP. In this paper we combine x-ray diffraction and excitation photoluminescence analyses of CuPt-ordered GaInP, and comparing the results to theoretical predictions for the dependence of the band structure on order parameter, determine the values of the band-gap reduction and crystal-field splitting parameters for the perfectly ordered alloy. ͓S0163-1829͑98͒06447-9͔

Shortwave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In 0.28 Ga 0.72 As 0.25 Sb 0.75 allowed for lattice matching to GaSb and cutoff wavelengths of 2.9 lm at 250 K and 3.0 lm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7 Â 10 10 Jones and 1 Â 10 10 Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures. V