Generalized blockaded reservoir and quantum-well electron-transfer structures (BRAQWETS): modeling and design considerations for high performance waveguide phase modulators

An equivalent circuit incorporating quantum capacitance and the concept of transcapacitance was derived in order to elucidate the interrelations among several figures of merit and the maximum intrinsic speed and their dependence on various design parameters for waveguide phase modulators based on the band-filling effect and, in particular, for a prototype blockaded reservoir and quantum-well electron transfer structure (BRAQWETS). In addition, the performance potentials of various BRAQWETS layer designs, which were generalized to allow up to four quantum wells for basic period as well as a novel three-terminal symmetric device configuration, were compared quantitatively by numerical simulation. Design guidelines for maximizing the performance of BRAQWETS waveguide phase modulators are given. It is shown that, for equal amount of residual intensity modulation per π phase shift, BRAQWETS can provide the best combination of low drive voltage (or power), high speed, good phase-shift linearity, and low background absorption among the currently known phase-modulator structures