Optical Pulse Multiplexing And High Resolution Filtering Based On A Tunable Silicon Optical Delay Line

As a basic optical component,the tunable optical delay line(ODL)has broad applications in optical communications and microwave photonics.With the development of integrated photonics,the optical chips made of silicon feature compact size and compatibility with CMOS technologies.These advantages generate wide applications for silicon photonic integrated circuits.Because of all these reasons,the tunable silicon ODL has attracted great research interest and attention in recent years.The thesis begins with the design of tunable silicon ODLs.The design of silicon waveguides,optical switches and grating couplers is described in details.Next,we study the applications of tunable silicon ODL in optical pulse multiplexer and microwave photonic filtering.On the application of optical pulse multiplexer,three different structures including optical time division multiplexer,wavelength division multiplexer and mode division multiplexer are theoretically analyzed and simulated.These structures can all be implemented with the tunable silicon ODL as a basic element.We also simulate the optical pulse multiplexer using the structures described above.On the application of microwave photonics,we propose a high-resolution reconfigurable microwave photonic notch filter based on the silicon ODL.The filter uses a four-path ODL line as the basic structure and can be reconfigured as a first-,second-or third-order filter.When the filter is reconfigured as the first-order filter,it can provide three spectra with different free spectral ranges(FSRs).All the reconfigured microwave photonic filters have an FSR of less than 1GHz,thus providing high resolution filtering.In addition,all filters are tunable in center frequency.The bandwidth of the second-and third-order filters is also tunable.