Ultrahigh finesse fiber Fabry-Perot interferometers

Fiber Fabry-Perots have been built with a finesse of 500 and throughput of 30-40 percent. The devices are piezoelectrically scanned and operate at 1.52μm, and have free spectral ranges of 1000, 500, 333, and 250 MHz, with linewidth resolution as small as 0.5 MHz. The sources of loss which limit the attainable finesse have been identified and analyzed.