Patent ID: 7039079

Claim:
A laser comprising: first and second mirrors forming a laser resonator; a gain medium located in said laser resonator for generating laser radiation on being energized, said laser radiation being plane polarized in a first polarization orientation; means for energizing said gain medium; an electro-optical switch located in said laser resonator and arranged such that said generated laser radiation from said gain medium is transmitted through said optical switch in a first direction to said first mirror and is reflected by said first mirror in a second direction opposite to said first direction, said reflected laser radiation being transmitted through said optical switch in said second direction opposite to said first direction; said electro-optical switch being switchable between an activated state and a deactivated state; said electro-optical switch being configured such that, when in said activated state, the polarization orientation of said first and second direction transmitted laser radiation is rotated from said first orientation to a second orientation, and, when in said deactivated state, the polarization orientation of said first and second direction transmitted laser radiation remains in about said first orientation; and a polarization selective device located in said laser resonator between said electro-optical switch and said gain medium, said polarization selective device arranged to permit circulation in said laser resonator of said laser radiation in said first polarization orientation and to restrict circulation of said laser radiation in said second polarization orientation.