Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technolog...Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technologies for large-scale photonic integrated circuits are described,including polarization handling,light non-reciprocity and loss reduction.The design rule for polarization beam splitters based on asymmetrical directional couplers is summarized and several novel designs for ultra-short polarization beam splitters are reviewed.A novel concept for realizing a polarization splitter–rotator is presented with a very simple fabrication process.Realization of silicon-based light non-reciprocity devices(e.g.,optical isolator),which is very important for transmitters to avoid sensitivity to reflections,is also demonstrated with the help of magneto-optical material by the bonding technology.Low-loss waveguides are another important technology for large-scale photonic integrated circuits.Ultra-low loss optical waveguides are achieved by designing a Si3N4 core with a very high aspect ratio.The loss is reduced further to,0.1 dB m21 with an improved fabrication process incorporating a high-quality thermal oxide upper cladding by means of wafer bonding.With the developed ultra-low loss Si3N4 optical waveguides,some devices are also demonstrated,including ultra-high-Q ring resonators,low-loss arrayed-waveguide grating(de)multiplexers,and high-extinction-ratio polarizers.展开更多
There is introduced a new low-reaction, highly-loaded axial compressor design concept which is coupled with boundary layer suction method. The characteristic features of the concept are made clear through its comparis...There is introduced a new low-reaction, highly-loaded axial compressor design concept which is coupled with boundary layer suction method. The characteristic features of the concept are made clear through its comparison with the MIT boundary layer suction compressor. Also are pointed out the potential applications of this concept as well as its key technological problems. Based on this concept, a single-stage, low-reaction and low-speed axial compressor is constructed in association with analysis and computation of boundary layer suction on vanes with the aid of a three-dimensional numerical approach. The results attest to the effectiveness of this way to control separation in blade cascades by the boundary layer suction and the feasibility of this proposed design concept.展开更多
基金This research is supported by DARPA MTO under the CIPhER contract no.HR0011-10-1-0079 and iPHOD contract no.HR0011-09-C-0123The authors thank S Rodgers,D Blumenthal,MJR Heck,M-C Tien,CM Bruinink,A Leinse and RG Heideman for their useful discussions and expertise.
文摘Silicon-based large-scale photonic integrated circuits are becoming important,due to the need for higher complexity and lower cost for optical transmitters,receivers and optical buffers.In this paper,passive technologies for large-scale photonic integrated circuits are described,including polarization handling,light non-reciprocity and loss reduction.The design rule for polarization beam splitters based on asymmetrical directional couplers is summarized and several novel designs for ultra-short polarization beam splitters are reviewed.A novel concept for realizing a polarization splitter–rotator is presented with a very simple fabrication process.Realization of silicon-based light non-reciprocity devices(e.g.,optical isolator),which is very important for transmitters to avoid sensitivity to reflections,is also demonstrated with the help of magneto-optical material by the bonding technology.Low-loss waveguides are another important technology for large-scale photonic integrated circuits.Ultra-low loss optical waveguides are achieved by designing a Si3N4 core with a very high aspect ratio.The loss is reduced further to,0.1 dB m21 with an improved fabrication process incorporating a high-quality thermal oxide upper cladding by means of wafer bonding.With the developed ultra-low loss Si3N4 optical waveguides,some devices are also demonstrated,including ultra-high-Q ring resonators,low-loss arrayed-waveguide grating(de)multiplexers,and high-extinction-ratio polarizers.
基金National Defense Basic Research Program of China
文摘There is introduced a new low-reaction, highly-loaded axial compressor design concept which is coupled with boundary layer suction method. The characteristic features of the concept are made clear through its comparison with the MIT boundary layer suction compressor. Also are pointed out the potential applications of this concept as well as its key technological problems. Based on this concept, a single-stage, low-reaction and low-speed axial compressor is constructed in association with analysis and computation of boundary layer suction on vanes with the aid of a three-dimensional numerical approach. The results attest to the effectiveness of this way to control separation in blade cascades by the boundary layer suction and the feasibility of this proposed design concept.
