NESTED-CAVITY OPTICAL PARAMETRIC OSCILLATOR FOR FAST FREQUENCY TUNING

摘要

Doubly resonant optical parametric oscillator with achromatic phase-maintaining pump reflection comprising a source (11) of pump radiation (fp), a non linear crystal (7) situated within two resonant cavities for the signal (fs) and complementary (fc) radiations of respective optical lengths ls and lc„ and forming a doubly resonant resonator for a single pair of longitudinal signal and complementary modes, the crystal is of prismatic shape with its rear face (9) inclined along a non zero angle α with respect to the direction x orthogonal to the direction z of propagation of the radiations, the crystal (7) being moveable within the plane xz. The crystal (7) is moveable along a direction forming a non zero angle ß with respect to the direction x to enable fast frequency scanning of the oscillator, the value of ß is fixed so that the movement of the crystal (7) is accompanied by a change in the respective optical lengths ls and lc of the two resonant cavities in a ratio such that the double resonance condition between the longitudinal modes of each cavity is maintained and as a result the values of the frequencies fs and fc are continuously tunable over a wide range without having to use a device for monitoring and correcting cavity lengths capable of maintaining the coincidence of modes between the two cavities. Figure for the abstract: Fig 4