Quantum well intermixing for wavelength-agile photonic integrated circuits

As the telecommunications industry enters the twenty-first century the demand for bandwidth continues to increase. Applications requiring vast amounts of bandwidth continue to be developed and introduced into a fiber optic network that will soon be overloaded. The advent of wavelength division multiplexing (WDM) has greatly increased the quantity of data transported within each optical fiber, yet increased the cost of system upkeep. Several key technologies are poised to revolutionize the communications industry. The introduction of widely-tunable lasers that are capable of tuning to any channel on the international telecommunications union (ITU) grid will dramatically reduce the cost of system upkeep through sparing functions, allowing system operators to reduce laser inventory, replacing fixed wavelength lasers with tunable lasers. Next generation networking applications using tunable lasers are being explored for increasing the functionality of the system. Another key technology, the photonic integrated circuit (PIC), will allow for cost reduction through monolithic integration. Beyond simple issues of cost reduction come the possibility of high functionality devices allowing a far greater use of system resources and the development of new network architectures based on these devices. This work involves the coupling of these two technological advancements to create a new breed of wavelength agile PICs. These devices are the ideal building blocks for the development of next generation, efficient, high bandwidth fiber optic networks. A novel processing technique based on quantum well intermixing (QWI) was developed specifically for this purpose. The QWI process allows for the formation of multiple quantum well band edges, ideally one specific to each integrated component. The process was applied to widely tunable sampled grating distributed Bragg reflector (SG-DBR) lasers with the goal of improving device characteristics. The applicability of the process to the fabrication of wavelength agile PICs is demonstrated through the monolithic integration of electro-absorption modulators possessing a unique quantum well band edge. The integrated devices exhibited excellent characteristics in terms of output power, tuning range, side mode suppression ratio, extinction, and bandwidth.