OPTICAL RESONATOR BASED ON A GRATING

摘要

The optical resonator according to the invention resonates at one frequency, either the signal or idler frequency. The optical resonator is fed with a pump wave (PB) produced with a laser source (501). The resonator comprises an optically nonlinear medium component (510), two mirrors around the medium component on its optical axis, a first (521) and a second mirror (522), and at least one mirror outside the optical axis of the medium component. The first mirror is on the incoming side of the medium component and the second mirror on the outlet side of the medium component. The medium component transforms the pump beam into a signal and idler frequency. At least one of the mirrors of the resonator is focusing at the resonant frequency and the focus is located in the medium component. One of the mirrors outside the optical axis of the medium component of the resonator is a grating (524), which is highly reflecting at the resonant frequency. The object of the grating is to produce a sufficient frequency selectivity, so that the optical resonator operates in a stable manner in one longitudinal resonator mode without mode hops. Additionally the grating makes possible the adjustment of the wavelengths of the signal and idler beams, because by changing the grating angle the wavelength resonating in the resonator can be selected. The structure according to the invention makes possible the use of a continuously operating laser device, whereby the outgoing beam (IB) is also continuous.