Design and Analysis of High-Speed, High-Contrast All-Optical Modulator Based on CdSe Quantum Dot-Doped Glass

To elucidate the theoretical foundation of an all-optical modulator (AOM) based on semiconductor quantum dots (QDs), numerical analysis have been performed, which is supported by the rate equations. Coupled rate and propagation equations have been solved toward investigating the carrier dynamics and optical behavior of the introduced AOM. A modulation depth (MD) of ~96% has been achieved in the output probe signal at the telecommunication wavelength of 1522 nm through an active planar waveguide design on silicon platform with a length of 200 μm for a pump power density of 5.6 MW/m² at the visible wavelength of 460 nm. Results indicate that the MD remains constant, until the pump frequency exceeds 71 GHz; the higher the pump frequency, the lower the MD. The throughput extinction ratio of the AOM is ~15 dB at the mentioned roll-off frequency. The MD decreases to ~45% while the modulation frequency reach to 1 THz. Also, the designed AOM based on cadmium selenide (CdSe) QDs operates with the switching energy of ~10 fJ.