Research On Nonuniformly Injected Semiconductor Optical Amplifiers

Due to their advantages such as small size, low power consumption, high nonlinearity, high speed, wide operation wavelength, and convenient for integration with other devices and so on, semiconductor optical amplifiers (SOAs) have found many potential applications in WDM and OTDM based all-optical networks, including all-optical signal processing, optical logic devices, wavelength conversion, and OTDM signal demultiplexing. Nonuniformly injected SOAs can improve carrier density hole-burning effects and have more stable gain and higher saturation output power than conventional SOAs. The device characteristics of nonuniformly injected SOAs has been studied in details using advanced numerical methods in this thesis.Numerical simulation for nonuniformly injected SOAs is an important basis for the device characterization, fabrication, and applications. We can conveniently and fleetly obtain the device characters and the effects of each design parameter through numerical simulation.In this thesis, the theoretical model and the characteristics of nonuniformly injected SOAs were studied systematically via numerical simulations, which includes the following aspects:1. The basic structures and operating principles of nonuniformly injected SOAs are described and discussed, based on which, material gain and spontaneous emission of semiconductor are analyzed. The carrier rate equation and a set of optical-field traveling-wave equations have been derived based on a random expanding of the optical fields within the cavity of the devices.2. An one-dimensional static-state model has been established by dividing the SOA into many equal subsections and considering the full-band ASE fields. Then, the numerical model was successfully implemented by using carrier density iteration method. The best condition of current injection is decided by analysis. The injected carrier density, ASE field and distributions of optical signal fields along the cavity of the devices are analyzed. Meanwhile, the affect of various parameters on the properties of the devices are simulated.3. A field-based time-domain dynamic model for nonuniformly injected SOA is developed. SS-TDM is used for the numerical implementation of the model. The time-domain dynamic properties of high bit-rate signal amplified by the SOAs were obtained, and the effects of various designing and operating parameters on the device characteristics were analyzed in details.4. A spectral-domain simulation model for nonuniformly injected SOAs was established and implemented by using extended transfer matrix formalism based on the time domain results. Then, the spectral-domain properties of nonuniformly injected SOAs with different device and operating parameters are analyzed.