High-speed optical systems based on electroabsorption modulators

Due to the explosive demand for Internet access and traffic, research in high-capacity optical fiber transmission has accelerated all over the world. Wavelength division multiplexing (WDM) has emerged in the past decade with over 6 Tbit/s transmission demonstrations. However, there is still considerable research in extending the capacity of a single wavelength system by time division multiplexing (TDM), which allows for an increased spectral efficiency for future WDM systems. For high-speed TDM systems, electroabsorption (EA) modulators, with their high-speed, low drive voltage, high extinction ratio and potential for monolithic integration with other opto-electronic components, have become very significant devices.; This thesis investigates and demonstrates various transmitter and receiver subsystems based on EA modulators for future high-speed electrical and optical TDM systems. A 30 Gbit/s electrical TDM system is described, where the EA modulators are used as high-speed data encoding transmitters. The EA modulators are then demonstrated for a variety of functions required in optical TDM systems. A novel simultaneous optical demuitiplexer and detector operation is proposed and implemented, which is suitable as a channel add/drop multiplexer and as a compact OTDM demultiplexing receiver. The high-speed switching capability of these devices is also demonstrated with sub-4 ps optical short pulse generation at frequencies ≥30 GHz by a dual-drive scheme of a high-saturation power EA modulator. Also, integrated tandem EA modulators, which achieve an extinction ratio of 50 dB, are investigated for >100 Gbit/s OTDM applications. Finally, these devices are employed at 30 GHz to demonstrate a 120 Gbit/s (4 x 30 Gbit/s) OTDM system, with error-free operation and an average 120 Gbit/s sensitivity of −22.6 dBm.