Tbit/s Optical Switches and Logic Gates: Towards Tunable Operation Near 1.55 Micrometers

摘要

In the performed research work, wavelength dependence (effects of detuning) and a possibility of tunable operation of the resonant soliton switches and logic gates have been investigated. A dramatic difference in the response to detuning between the semiconductor NLDC and atomic SIT-soliton NLDC has been revealed. A typical tunability range of a model resonant soliton NLDC has been assessed quantitatively and compared with a requirement for the device operating spectral range in WDM systems (applied by the gain bandwidth of erbium-doped fiber amplifiers). Extensive literature search has been performed to identify semiconductor materials which are suitable for implementation of the resonant soliton switches capable of tunable operation near the optical communication wavelength (1.55 micrometers). A number of semiconductor systems with the required excitonic absorption features have been selected including InGaAs/InAlAs MQW, InGaNAs/GaAs MQW, InGaAs/InP MQW, InGaAsP/InP MQW and GaSb/ AlGaSb MQW structures. Modeling of operation of InGaAs/InAlAs MQW NLDC near 1.55 micrometers has been performed; a tunability range of about 25 nm and a mean switching contrast ratio of 20:1 within this range have been demonstrated numerically. A new device design has been suggested as a possible way to substantially increase the device tunability range. In the new design, semiconductor quantum-dot-doped glass has been used as a material for the constituent waveguides of NLDC. The use of PbS quantum dots has lead to a broader device tunability range (at least, 65 nm) near 1.55 micrometers.