Waveguide electrooptic modulator with a limiting modulation frequency higher than 10 GHz

A study was made of the main characteristics of a waveguide electrooptic modulator with an "interrupted cumulative interaction" proposed earlier by the present authors. A Y-cut LiNbO₃ crystal was used in the form of a structure in which a bent optical waveguide passed out of the interelectrode zone and returned after a certain distance. Calculations were made of the frequency dependence of phase modulation taking into account attenuation of a microwave modulating wave in the modulator circuit. In the low-frequency range the measured half-wave modulator voltage was 4.5 V at the wavelength of 0.63 μm. The results of calculations and measurements in the low-frequency range showed that this structure can provide phase modulation slightly greater than π/2 at a control voltage of 4.5 V and modulation frequencies of 13–15 GHz.