title: VECSEL gain characterization.
abstract: We present the first full gain characterization of two vertical external cavity surface emitting laser (VECSEL) gain chips with similar designs operating in the 960-nm wavelength regime. We optically pump the structures with continuous-wave (cw) 808-nm radiation and measure the nonlinear reflectivity for 130-fs and 1.4-ps probe pulses as function of probe pulse fluence, pump power, and heat sink temperature. With this technique we are able to measure the saturation behavior for VECSEL gain chips for the first time. The characterization with 1.4-ps pulses resulted in saturation fluences of 40-80 μJ/cm2, while probing with 130-fs pulses yields reduced saturation fluences of 30-50 μJ/cm2 for both structures. For both pulse durations this is lower than previously assumed. A small-signal gain of up to 5% is obtained with this technique. Furthermore, in a second measurement setup, we characterize the spectral dependence of the gain using a tunable cw probe beam. We measure a gain bandwidth of over 26 nm for both structures, full width at half maximum.
authors.affiliation: Department of Physics, Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland. mangoldm@phys.ethz.ch
authors.forename: Mario
authors.initials: M
authors.lastname: Mangold
authors.forename: Valentin J
authors.initials: VJ
authors.lastname: Wittwer
authors.forename: Oliver D
authors.initials: OD
authors.lastname: Sieber
authors.forename: Martin
authors.initials: M
authors.lastname: Hoffmann
authors.forename: Igor L
authors.initials: IL
authors.lastname: Krestnikov
authors.forename: Daniil A
authors.initials: DA
authors.lastname: Livshits
authors.forename: Matthias
authors.initials: M
authors.lastname: Golling
authors.forename: Thomas
authors.initials: T
authors.lastname: Südmeyer
authors.forename: Ursula
authors.initials: U
authors.lastname: Keller