Phased-Array Wavelength Demultiplexers and Their Integration with Photodetectors

摘要

Wavelength Division Multiplexing (WDM) exploits the huge bandwidth of the opticalfiber by parallel transmission of several independent channels located at different wavelengths and in addition has the potential of all-optical routed networks. A key component in such a WDM-system is a low-loss wavelength demultiplexer for spatial separation of the different channels. This thesis describes the design, realization and characterization of wavelength demultiplexers for 1.55 micrometer-window and their monolithic integration with photodetectors. The wavelength demultiplexer is based on the dispersive properties of a planar waveguide array. In this thesis it is demonstrated that these demultiplexers combine low-loss with excellent spectral resolution. The polarization dependence of phasar demultiplexers has been analyzed in detail. The wavelength response of the demultiplexer has been flattened by employing multimode output waveguides. A novel waveguide array demultiplexer is proposed employing Multi Mode Interference (MMI) couplers in a generalized NxN Mach-Zehnder Interferometer configuration. This device has a potential for very low-loss operation and high transmission uniformity of the individual channels. Finally, a new measurement technique is demonstrated for non-destructive measurement of waveguide losses, which is a first step towards full-wafer characterization of integrated optic components.