Patent ID: 6590911
Filing Date: 2003-07-08
Classification: H01S

Abstract:
A laser, comprising:a laser resonator terminated by first and second mirrors; a gain-medium located in said laser resonator; an optical pump for energizing said-gain medium, thereby causing fundamental radiation having a fundamental frequency to circulate in said laser resonator; a first optically-nonlinear element located in said laser resonator between said gain-medium and said first mirror and cooperatively arranged with said first mirror such that a first portion of said fundamental radiation is converted to second-harmonic radiation on traversing said first optically-nonlinear element from said gain-medium to said first mirror and a first portion of said second-harmonic radiation is reflected from said first mirror back into said optically nonlinear element a second portion of said second-harmonic radiation being transmitted out of said laser resonator by said first mirror; means being provided between said first optically-nonlinear element and said first mirror for adjusting the phase relationship between said first portion of said reflected second-harmonic radiation and said fundamental radiation such that said reflected first portion of said second-harmonic radiation is reconverted to fundamental radiation by said first optically-nonlinear element, thereby providing passive modelocking of said fundamental radiation, said passive modelocking causing said fundamental radiation to circulate in said resonator as a sequence of pulses; and a second optically-nonlinear element located outside of said laser resonator and arranged to convert said transmitted second portion of said second-harmonic radiation to one of third-harmonic radiation or fourth-harmonic radiation.