The performance of light intensity modulation using guided-to-radiation mode coupling through the electrooptic effect is investigated theoretically and experimentally. We show that high modulation efficiency is obtainable if a heterostructure waveguide is employed that has appropriate refractive indices to bring forth large field overlap of the two coupled modes. Waveguides of Nb2O5 or Li(Nb0.1 Ta0.9)O3 film on a LiTaO3 substrate structure could have modulation efficiency of more than 100 dB/cm. The experiment was carried out in a Nb2O5-LiTaO3 structure fabricated by rf reactive sputtering, and we obtained the measured modulation depth as high as 45 dB/cm at an applied voltage of 400 V across 55-µm gap electrodes.
© 1984 Optical Society of America
Hidetoshi Onodera, Ikuo Awai, Masamitsu Nakajima, and Jun-ichi Ikenoue, "Light intensity modulation based on guided-to-radiation mode coupling in heterostructure waveguides," Appl. Opt. 23, 118-123 (1984)