Accurate measurement of ultralow loss in a high-finesse Fabry-Perot interferometer using the frequency response functions

We describe the accurate measurement of ultralow loss in a high-finesse Fabry-Perot interferometer using a diode-pumped Nd:YAG laser locked to the longitudinal mode with an active frequency-stabilization technique. By measuring the resonance full width and the free spectral range with the frequency response functions, and by measuring the transmission efficiency on resonance, the finesse and the loss at 1064 nm are accurately measured to be 78100 ± 1200 (reflectance of 99.99598 ± 0.00006%) and 1 5.9 ±2.0 × 10^–6 (15.9 ± 2.0 ppm), respectively.