Abstract

The recent progress in highly efficient volume holographic materials, such as dichromated gelatin (DCG), DCG/polymer grafts, Polaroid's DMP-128, and DuPont photopolymer, has stimulated a strong interest in applications requiring high-diffraction-efficiency holographic optical elements (HOEs), such as head-up displays, solar-control windows, IR mirrors, wavelength-division multiplexing gratings, holographic interconnects, holographic delivery systems, and holographic couplers. In some of these applications, the Bragg bandwidth must be tunable as well as very broad (>500 nm). Recent developments in volume holographic technology offer high diffraction efficiency (>99.8%), high-index modulation (>0.1), and tunable bandwidth over a broad range (5–500 nm). In this article, we discuss the optical properties and potential applications of Lippmann-Bragg broadband holographic mirrors, which represent a new class of volume holograms that are very different from those described by the Kogelnik model. The theoretical analysis of their optical properties includes examination of diffraction-efficiency spectral/angular characteristics as a function of hologram thickness and discussion of index modulation. We show that in order to obtain a uniform reflection bandwidth, a balanced relation between hologram parameters is required.

© 1990 Optical Society of America