We study a hybrid silicon organic high speed electro-optic phase shifter based on polymer infiltrated P-S-N (“S” refers to the slot) diode capacitor structure. This optical phase shift is realized based on index perturbation both inside the slot via Pockels nonlinearity and within the silicon ridges via the free carrier effect (carrier depletion). The combination of the polymer diode capacitor configuration with the low aspect ratio slot waveguide system leads to a promising method of constructing sub-THz speed optical modulators without sacrificing either modulation efficiency or energy consumption. By optimizing the waveguide geometry in terms of balancing effective index shift and device speed, at least 269 GHz bandwidth can be achieved with a high modulation efficiency of 5.5 V-cm when the diode capacitor is reverse biased by an external radio frequency (RF) voltage signal between the electrodes (optical propagation loss is acceptably low at 4.29 dB).
Low-loss high-speed traveling-wave silicon Mach-Zehnder modulator with reduced series resistance is studied in
microwave and optical measurements. Microwave impedance and propagation loss under reverse bias are characterized
by S-parameter measurements. Resonant loss due to series inductance-resistance-capacitance coupling limits microwave
performances of the traveling-wave modulator. High-speed optical performances are characterized, based on eyediagram
measurements in on-off keying at 10-32 Gb/s and constellation and eye-diagram measurements in differential
phase-shift keying at 20 Gb/s. Dispersion tolerance in error-free transmission in 10-Gb/s on-off keying and 20-Gb/s
differential phase-shift keying is obtained as +/-950 ps/nm and +/-220 ps/nm, respectively by path-penalty measurements.
Transmission performance in 10-Gbps on-off keying is comparable with lithium niobate Mach-Zehnder modulator.
Optical modulation is one of the key determinants to the operating speed of a network. In this work, we report an
accurate methodology to study high-speed eye diagram from electrical and optical simulation data of individual
modulators. The methodology constitutes electrical parameters such as capacitance, conductance and transitioning times
to model time response and effective complex refractive index from optical simulations of phase shifter arms and in turn
model the phase change and resultant loss induced by each arm. This methodology is suitable for interferometer-based
optical devices and has been applied to silicon-based depletion mode modulators at 10-, 40-Gbps.