High repetition rate, mode locked, figure eight laser with extracavity

Abstract

An optical pulse generator for producing mode-locked optical pulses comprises: a beam splitter; first and second optical loops coupled together by the beam splitter so as to define a figure eight optical path in which a light beam propagating toward the beam splitter in one of the first and second optical loops is split by the beam splitter to form two light beams propagating in opposite directions around the other one of the first and second optical loops; a direction dependent loss element disposed in the first optical loop for reducing the intensity of light propagating in a predetermined direction around the first optical loop; a nonlinear element disposed in the second optical loop and having an intensity dependent nonlinear optical transmission characteristic; an optical gain medium disposed in a selected one of the first and second optical loops; coupling apparatus for coupling pump light into the selected one of said first and second optical loops having the gain medium, and for coupling mode-locked optical pulses out of the optical pulse generator; and a feedback structure, coupled to the coupling apparatus, being responsive to light propagating therethrough for controlling the repetition rate of the mode-locked optical pulses.