Guided-wave Electrooptic Modulator Research Articles

Optical pulse generation using guided-wave electrooptic modulator with resonant electrodes and polarization reversal

This paper reports on optical pulse generation using a new guided-wave electrooptic (EO) phase modulator with long resonant electrodes and polarization reversal. Adopting polarization-reversal structure to a guided-wave EO modulator with long standing-wave resonant electrodes, high-efficiency optical modulation is obtained by the compensation of the transit-time effect. By operating a fabricated EO phase modulator with a large amplitude modulation signal, optical sidebands over 100 GHz were obtained. Furthermore, optical pulse trains of an ~ 25-ps pulsewidth and a 15.28-GHz repetition frequency were successfully obtained by controlling the generated optical sidebands by use of an optical synthesizer

Guided-Wave Electro-Optic Modulators Using Novel Electrode Structure of Coupled Microstrip Line Resonator

A novel structure of guided-wave electro-optic modulators is proposed and their operation of the optical intensity modulation is successfully confirmed. The modulators use a newly developed modulation electrode consisting of coupled microstrip lines. A high voltage can be induced by the resonance of the odd propagation mode to realize efficient electro-optic modulation in spite of the microstrip-line configuration. The properties of the coupled microstrip lines were analytically evaluated by using the method of conformal transformations and the effectiveness as a modulation electrode was presented. The modulation electrodes of the half-wavelength coupled microstrip line resonator were designed at 10 GHz and 26 GHz, where the electrode lengths were 3 mm and 1.2 mm, respectively. The modulators using these electrodes with the Mach-Zehnder interferometer of LiTaO 3 waveguides were fabricated. The measured modulation coefficient of the 26 GHz modulator normalized at 100 mW signal input was 0.13 rad.

Guided-wave electro-optic modulator using resonator electrode of coupled microstrip lines

A newly proposed electrode structure consisting of coupled microstrip-lines can achieve an efficient modulation by using the resonance of the odd propagation-mode. The modulator with the 1.2 mm-long electrode for 26 GHz operation was fabricated and its workability was experimentally confirmed.

Optical pulse generation by using quasi-velocity-matched guided-wave electrooptic phase modulator

A quasi-velocity-matched guided-wave electrooptic modulator was fabricated using a periodically domain-inverted LiTaO3. Band modulation characteristics around the designed modulation frequency and the generation of optical sidebands of about 100 GHz were confirmed experimentally. The trains of optical pulses below 20 ps were also generated by the compression of the optical sidebands from the modulator. It should lead to the construction of integrated optical pulse generators.

Simulation and analysis of silicon electro-optic modulators utilizing the carrier-dispersion effect and impact-ionization mechanism

A new type of Si guided-wave electro-optic modulator is proposed and analyzed. The modulator makes use of the impact-ionization mechanism for carrier generation, and the carrier-dispersion effect for electro-optic conversion. Both electrical and wave propagation properties of the modulator were examined by a two-dimensional device simulator and a three-dimensional waveguide simulator, respectively. Numerical estimates of phase modulation due to refractive-index change and intensity modulation due to optical absorption and radiation loss were obtained. One of important features of the prospected modulator is speed. The simulated turn-on and turn-off time of the modulator was less than 1 ns. GHz modulation is, therefore, possible for this class of modulators with device structure and doping profiles optimized for fiber coupling.

Generation of dark solitons under a cw background using waveguide electro-optic modulators

We propose a novel method for generating dark solitons with a cw background by using broadband guided-wave electro-optic modulators. The generated pulse can be amplified by stimulated Raman scattering to permit the observation of soliton effects in the fiber.