Abstract

Ultralow-loss and high-reflectance mirrors were produced by Japan aviation electronics industry Ltd. whose characteristic was measured in precisely. To determine a mirror reflectance, we used the frequency response function measurement and the cavity decay-time measurement method (the ring-down method).¹ As a result, a loss of 6 ± 6 ppm (6 ± 6 × 10⁻⁶ includes scatter and absorption), a transmittance of 1399 ± 39 ppm, and reflectance of 99.8595 ± 0.0033% were measured by the cavity decay-time measurement. A transmission efficiency η_t = 99.14 ± 0.86% can be calculated from the result. We found the transmission efficiency was 100% within the error. Reflected optical power is almost zero at the point of resonant frequency shown in Fig. 1. The loss measured here is the lowest at 1064 nm to our knowledge. The finesse was cross checked with measurement of frequency response function whose result is good agreement with the result of decay-time measurement. The high-transmission and high-reflectance mirror is possible to make an ideal FP cavity which used mode cleaner for the Gravitational wave antenna. Such mirrors will be one of the key technology not only for fundamental optical science but also for industrial applications.

© 1995 IEEE