14 July 1988 Effects Of Profile Replication On Diffraction Anomalies In Multilayer-Overcoated Gratings
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Abstract
An analysis is made of anomalous resonance effects on multilayer-overcoated, low-efficiency gratings using the extinction theorem technique for various degrees of grating replication at overlayer interfaces. For wavelength-to-grating-period ratios such that only the specular and -1 order are reflected from the grating, an enhancement of the 2% nominal efficiency in the -1 order can be realized. Anomalously high diffraction efficiency at resonance, which may exceed 50% in the -1 order, results from the coupling of the incident beam into guided waves supported by the multilayer assembly. Previously, resonance effects were studied assuming perfect replication of the substrate grating profile at each film interface. However, perfect transfer of the grating relief to the film boundaries does not occur in all instances; it depends on the grating and film characteristics as well as the conditions during deposition. In this paper, we investigate the effect of nonreplication of the grating profile at film interfaces on anomalous diffraction, while assuming a transition from trapezoidal profile at the grating substrate to a rounded relief at the top surface of the multilayer structure.
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L F DeSandre, L F DeSandre, J. Merle Elson, J. Merle Elson, } "Effects Of Profile Replication On Diffraction Anomalies In Multilayer-Overcoated Gratings", Proc. SPIE 0927, Wave Propagation and Scattering in Varied Media, (14 July 1988); doi: 10.1117/12.945825; https://doi.org/10.1117/12.945825
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