title: Ultrasensitive and high-dynamic-range two-photon absorption in a GaAs photomultiplier tube.
abstract: We demonstrate improved efficiency and dynamic range for two-photon absorption at 1.5 microm in a photoelectron-counting GaAs photomultiplier tube. cw laser measurements show pure two-photon absorption occurring in the device from average powers of 1.3 microW to nearly 1 mW. We use the detector to implement an autocorrelator with peak-power x average-power sensitivity of 1.7 x 10(-4) (mW)(2) and discuss practical ways to reduce this figure of merit to as low as 1 x 10(-5) (mW)(2).
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Roth
authors.forename: T E
authors.initials: TE
authors.lastname: Murphy
authors.forename: Chris
authors.initials: C
authors.lastname: Xu