Abstract

The spectral-absorptance curves of quarter-wave reflectors are quite asymmetric in general as a result of absorption in the layers. The maximum electric field E in an infinite stack is in the center of the high-index (low-index) layer at the low-frequency (high-frequency) end of the high-reflection band. Thus, the absorptance minimum of a stack having much greater absorption in the high-index material occurs at ω > ω_c (band center). Operation at ω > ω_c could increase the damage resistance if the high-index material is easily damaged. At ω_c, E decays rapidly. As ω departs from ω_c in an infinite reflector, E penetrates deeper into the coating, with no decay at the band edges. The peak-to-peak distance in an infinite dielectric stack is constant for all frequencies in the band. By using the continuity of E and dE/dz, E can be obtained from E = 0 at the metallic substrate or, in an infinite stack, from E = 0 at the reflector surface for ω = ω_c or E = 0 in the center of the high- or low-index layer at the band edges. Simple closed-form approximations for the spectral absorptance and the phase of E are accurate and sufficient for present applications.

© 1979 Optical Society of America

A simple method for calculating the optical properties of multilayer-dielectric reflectors*

M. Sparks
J. Opt. Soc. Am. 67(11) 1590-1594 (1977)

Nearly perfect multilayer dielectric reflectors: theory

M. Flannery, E. Loh, and M. Sparks
Appl. Opt. 18(9) 1428-1435 (1979)

Maximum reflectance of multilayer dielectric mirrors in the presence of slight absorption

C. K. Carniglia and Joseph H. Apfel
J. Opt. Soc. Am. 70(5) 523-534 (1980)

Diffraction and diffuse scattering from dielectric multilayers

J. M. Elson
J. Opt. Soc. Am. 69(1) 48-54 (1979)

Temperature dependence of absorptance in laser damage of metallic mirrors: I. Melting

M. Sparks and E. Loh
J. Opt. Soc. Am. 69(6) 847-858 (1979)