Ultralow-loss mirror of the parts-in-10(6) level at 1064 nm

We describe an ultralow-loss and high-reflectance mirror at 1064 nm. A Fabry-Perot cavity is fabricated with two mirrors to measure the finesse and the transmission efficiency on resonance. The finesse was cross checked by two different methods: measurements of the cavity decay time and of the frequency-response function. As a result, a loss of 6 +/- 6 x 10(-6) (6 +/- 6 parts in 10(6), scatter and absorption) and a finesse of 2236 +/- 54 were measured during the cavity decay time. This result coincides with that of the response function within accuracies cited above. To our knowledge, the loss is the lowest obtained at 1064 nm.