Patent ID: 7532657

Claim:
A laser oscillator, comprising: a non-planar optical ring resonator; an optical amplifier element on an optical path inside the optical resonator, (i) the optical path in the optical resonator having an even number of optical reflections per resonator circuit or round-trip, which is formed by total reflections at each side face of two right-angle prisms and by deflection by a lens through which an off-center position of the optical path passes, (ii) the transverse mode pattern of the laser light in the optical resonator rotating with each resonator circuit or round-trip by a rotation angle other than zero degrees, 90 degrees or 180 degrees, the cumulative rotation angle increasing or decreasing monotonically as the number of circuits or round-trips increases; and polarization maintaining means that maintains the polarization direction of the laser light through one resonator circuit or round-trip.