An optimal design of a slot waveguide is presented for realizing an ultrafast optical modulator based on a 220 nm silicon wafer technology. The recipe is to maximize the confinement and interaction between optical power supported by the waveguide and electric field applied through metallic electrodes. As height of waveguide is fixed at 220 nm, the waveguide and slot width are optimized to maximize the confinement factor of optical power. Moreover, metal electrodes tend to make the waveguide lossy, their optimal placement is calculated to reduce the optical loss and enhance the voltage per unit width in the slot. Performance of an optimally designed slot waveguide with metal electrodes as ultrafast modulator is also discussed.

A novel all optical measurement scheme is proposed to measure wideband microwave frequencies up to 30 GHz. The proposed method is based on a four-wave mixing (FWM) approach in a semiconductor optical amplifier (SOA) of both even order side-bands generated by an unknown microwave frequency modulating an optical carrier. The optical power of a generated FWM signal depends on frequency spacing between extracted side-bands. A mathematical relation is established between FWM power and frequency of an unknown signal. A calibration curve is drawn based on the mathematical relation which predicts the unknown frequency from power withdrawn after FWM