CRITICAL-FIELD PATTERNS IN OPTICAL FIBONACCI MULTILAYERS

Optical coatings with 13, 34, 55, and 89 quarter-wave layers of high- and low-index dielectric materials arranged in Fibonacci sequences F6, F8, F9, and F10, respectively, were deposited with use of a reactive low-voltage ion plating process. The calculated average transmission ( T(ave)) for phi = (1/2 +/- 1/4)pi follows a power law T(ave) almost-eq ual-to N(m)-delta, where N(m) is the number of optical quarter-wave la yers in a Fibonacci sequence F(m). The critical exponent delta for the se multilayers is compared with a renormalization calculation of the e xponent governing the total energy width for an electronic system of F ibonacci layers. Spectral-transmittance measurements of the experiment al Fibonacci multilayers show some deviation from the calculated spect ral transmittance, which is due primarily to absorption in the short-w avelength range, but these measurements do still indicate that the obs erved optical field patterns are critical.