Patent ID: 8094368

Claim:
An optical parametric oscillator, comprising: a laser pump source operable to provide pump pulses of light of wavelength in the range from 300 nm to 500 nm, which pump pulses are of a duration of at most 500 fs and at a predetermined repetition rate of at least 0.1 MHz; an oscillator cavity including a first focus; a nonlinear optical crystal comprising either (a) BiB 3 O 6 or (b) Bi 1-x M x B 3 O 6 where M is Ga, In, Sc or one of the rare earth elements and 0<x≦0.5, in a collinear phase-matching configuration, located at the focus of said oscillator cavity; the laser pump source being located external to the oscillator cavity and arranged to direct the pump pulses through said crystal to synchronously pump said crystal and thereby cause the crystal to generate signal pulses and idler pulses from the pump pulses, the oscillator cavity being arranged to direct the signal pulses along the oscillator cavity and to output output pulses derived from the signal pulses.