title: Nearly diffraction-limited signal generated by a lower beam-quality pump in an optical parametric oscillator.
abstract: The beam quality of an optical parametric oscillator (OPO) within a singly resonant, confocal-positive branch unstable resonator is investigated. Resonator configurations have been found in which the beam quality of the outgoing signal exceeds the beam quality of the pump. Cavity magnification and pump-pulse duration are found to determine the signal beam quality. It is shown that signal M2 decreases with increasing pump-pulse duration for a given cavity magnification. In an experimental demonstration of a LiNbO3 OPO within an unstable resonator, pumped by a multitransversal mode beam, a signal beam with an almost-single transversal mode has been generated, whereas the multitransversal mode behavior of the pump beam is projected on the idler beam.
authors.affiliation: Electro-optics Division of Soreq Nuclear Research Center, Yavne 81800, Israel. pearl@soreq.gov.il
authors.forename: Shaul
authors.initials: S
authors.lastname: Pearl
authors.forename: Yosi
authors.initials: Y
authors.lastname: Ehrlich
authors.forename: Shlomo
authors.initials: S
authors.lastname: Fastig
authors.forename: Salman
authors.initials: S
authors.lastname: Rosenwaks