Theoretical Analysis And Experiment On 2×2 MMI-MZI Optical Switch Based On InP

The research work of this thesis was supported by grants from National Basic Research Program of China, "Basic Research on Integrated Optoelectronic Devices and Microstructure Optical Fibers with Structure and Technology Innovations for Future Advanced Optical Communications" (2003CB314900).Nowadays, optoelectronic devices face the turning point that photonic integrated circuits (PICs) are rapidly replacing modules based on discrete devices, because the former offer the advantages of smaller dimension, lower power, lower cost, better performance and higher reliability compared to the latter. PICs have already become extremely attractive research domain in the area of optical communications and optoelectronics. Optical switching is a cornerstone of wavelength-division-multiplexed networks based on optical add-drop multiplexers, cross-connects, and other advanced optical system architectures, whose PICs become the significant research subjects.In this thesis, which is the foundational part of research on monolithically integrated ROADM (Reconfigurable Optical Add-Drop multiplexer), a 2×2 optical switch, as its key component, has been designed and fabricated, which is based on InP and consists of dual multimode interference (MMI) couplers that are connected in the Mach-Zehnder-interferometer (MZI) configuration. On the other hand, vertical-taper coupler was introduced into the photonic integration using asymmetric twin-waveguide (ATG) technology and its performance was simulated and analyzed when it was used as the coupler of ATG PIN photodiode. The following contents listed the main work of this thesis:1. The principles, characteristics, and application of the five kinds of main technologies of PICs were analyzed and summarized; meanwhile, their advantages and shortages were concluded. The mixed usage of PICs was also discussed.2. Photonic Integration using ATG technology with vertical-taper coupler was firstly introduced. And a waveguide coupled p-i-n photodiode using vertical-taper coupler, whose characteristic was analyzed and optimized, was designed. Compared to lateral-taper coupler, vertical taper has higher transfer efficiency and shorter length and requires simpler fabrication process if its epitaxial layer and characteristic parameters are rightly selected.3. Considering much factors, such as single mode operation, low polarization sensitivity, and good coupling efficiency and loose alignment tolerance between the waveguide and the fiber, the InP/InGaAsP 2×2 optical switch based on MMI-MZI was analyzed and designed in detail, which has a simple structure and is much easier to be integrated with other components. The fabrication tolerance was also discussed.4. The processing steps for fabricating InP/InGaAsP optical switch was found, and the measurement platform was setup. The modification and improvement of mask design, post-process and measuring equipment was put forward.