| Abstrakt: |
LiTaO_3 optical modulators have been developed using the technique of self-compensation for therma stability. By using two crystals in cascade, with optic axes 180° apart, and a half-wave plate between them with axis at 45°, the birefringence of each crystal is equal but opposite and there is no net change in birefringence with temperature. Aside from thermal stability, the optical modulator described damps out mechanical resonances caused by the piezoelectric properties of the crystals, and its thin-film substrate mounting is applicable to wideband modulation. Experimental measurements show that 95% modulation depth can be attained over a 25° C temperature range with virtually no change in the amplitude or phase of the modulated signal. |
