Guided-Wave EO Intensity Modulator Using Coupled Microstrip Line Electrode of Higher-Order Harmonic Resonance Combined with Polarization-Reversed Structure

A novel structure of a resonator type guided-wave electrooptic intensity modulator is introduced that uses a higher-order harmonic resonant electrode of coupled microstrip lines combined with polarizationreversed structure. The light modulation cancellation caused by the light transit-time effect in the resonant electrode, which is longer than the wavelength of the standing wave, is compensated for to enhance modulation efficiency. The modulator for 26 GHz operation was designed and fabricated with a LiTaO3 substrate. The modulation electrode is 9.03 mm long for seventh order harmonic resonance by RF signal. The workability of the modulator was confirmed by experiments with 1.3 μm wavelength light. key words: EO modulator, resonant electrode, higher order harmonic resonance, polarization reversed structure, transit-time effect, LiTaO3