Patent ID: 8279517

Claim:
A doubly resonant optical parametric oscillator with return of the pump radiation comprising, in the direction of out propagation of the pump radiation, a non-linear crystal ( 4 ) having a front face ( 6 A) and a rear face ( 6 B), a device ( 5 ) situated downstream of the rear face ( 6 B) of the crystal, defining with a first mirror ( 7 ) situated upstream of the front face ( 6 A) of the crystal a first resonant cavity for the signal radiation and with a second mirror ( 8 ) situated upstream of the front face ( 6 A) of the crystal defining a second resonant cavity for the complementary radiation, one at least of the two cavities being of adjustable length to ensure an operating mode of the oscillator which is one of mono-frequency and bi-frequency, the pump radiation at the frequency f p making an out path entering via the front face ( 6 A) of the crystal through the crystal ( 4 ) and exiting via the rear face ( 6 B) of the crystal, then, after reflection on the device ( 5 ), a return path entering via the rear face ( 6 B) of the crystal, the signal radiation at the frequency f s , making out-and-back paths in the first resonant cavity, the complementary radiation at the frequency f c , making out-and-back paths in the second resonant cavity, said three radiations exiting from the rear face of the crystal ( 6 B) with relative dephasing ΔΦ a =φ p a −(φ s a +φ c a ) and entering via the rear face of the crystal ( 6 B) with relative dephasing ΔΦ r =φ p r −(φ s r +φ c r ) after reflection on the device ( 5 ), the value of the relative dephasing spread ΔΦ ar =ΔΦ r −ΔΦ a determining, for a given type of phase tuning, the mono-frequency or bi-frequency operating mode of the oscillator, wherein the device ( 5 ) is a metallic mirror common to the two cavities, due to which the value of the relative dephasing spread ΔΦ ar is equal to π (mod. 2π) irrespective of the operating frequency of the oscillator; and wherein φ p a is the phase of the pump radiation measured at the level of the rear face of the crystal ( 4 ) during the out paths; φ s a is the phase of the signal radiation measured at the level of the rear face of the crystal ( 4 ) during the out paths; φ c a is the phase of the complementary measured at the level of the rear face of the crystal ( 4 ) during the out paths; φ p r the phase of the pump radiation measured at the level the rear face of the crystal ( 4 ) during the return paths; φ s r is the phase of the signal radiation measured at the level of the rear face of the crystal ( 4 ) during the return paths; and φ c r is the phase of the complementary radiation measured at the level of the rear face of the crystal ( 4 ) during the return paths.