Abstract

Superhigh-efficiency (SHE) holographic technology¹ can offer high reflectivities up to 99.9% (in Lippmann geometry), with regulated bandwidth and Bragg wavelength with near-IR, UV and visible spectrum. Those degrees of freedom are due to very flexible DCG processing with regulated shrinkage/swelling nonuniformity that can be analyzed by using the WKB method.² The additional degrees of freedom, unique for holographic technology, are related to the possibility of controlling refractive-index modulation amplitude and profile. In the first case, it is possible to regulate refractive-index modulation from 0.001 to at least 0.1, while in the second case, the refractive-index modulation profile can be adjusted from sinusoidal to quasi-rectangular. The latter effect can be monitored by spectroscopic measurement of second-harmonic line reflectivity and by reflectivities of the next harmonics. In particular, by using a specific DCG processing method, the reflectivity of the second harmonic can be tuned from zero-level (equivalent to perfectly sinusoidal refractive-index modulation) to ~95 % efficiency. The possible applications of this effect are discussed, especially in the case of Lippmann holographic window films.

© 1985 Optical Society of America