title: Characterization of thin-film losses with a synchronously pumped ringdown cavity.
abstract: We describe the use of a synchronously pumped ringdown cavity for measuring total optical losses, absorption and scattering, in thin optical films of arbitrary thickness on transparent substrates. This technique is compared with a single-pulse ringdown cavity regime and is shown to have a superior signal-to-noise ratio and resolution. We also provide an analysis of the factors affecting the resolution of the technique. Using this ringdown cavity pumped by a conventional mode-locked Ti:sapphire laser, we experimentally detect losses of only 58 +/- 9 and 112 +/- 9 parts per million in Ta2O5 and SiO2 films, respectively. To our knowledge, these are so far the lowest losses measured in thin films on stand-alone transparent substrates.
authors.affiliation: Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA. vaschen@engr.colostate.edu
authors.forename: Georgiy
authors.initials: G
authors.lastname: Vaschenko
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Godwal
authors.forename: Carmen S
authors.initials: CS
authors.lastname: Menoni
authors.forename: Claude
authors.initials: C
authors.lastname: Montcalm
authors.forename: Richard
authors.initials: R
authors.lastname: Blacker
authors.forename: Daniel
authors.initials: D
authors.lastname: Siegfried