Therotical And Experimental Investigation On Demultiplexing And Receiving Devices Based On Novel Microstructures

With the rapid development of information technology,it's becoming an urgent need for large capability,high speed transmission and management.Information technology will be push to a new stage by substituting photon technology or optoelectronic technology for micro-electronic technology,and developing optical integration or optoelectronic integration.The research in this thesis is supported by grants from The National Basic Research Program of China(No.2003CB314900),Key Program project of the National Natural Science Foundation of China(No: 90601002),the National High Technology Research and Development Program of China(No:2003AA31g050,2003AA312020, 2006AA03Z416,2007AA03Z418),and Program of Key International Science and Technology Cooperation Projects(No:2006DFB11110).In this thesis,a great deal of research work can be described as follow.Design and fabrication of arc microstructures;design and analysis of a new kind of photodetector with arc absorption cavity.Design and analysis of some new kinds of optical devices based on semiconductor microring resonators,which include coupled-microring waveguide reflector,coupled-microring resonator optical waveguide and compound coupled-microring photodetector.Design,analysis and fabrication of"one mirror inclined three mirror cavity"(OMITMiC) photodetector basing on InGaNAs/GaAs multi-quantum wells.The main achievements are listed as follows.1.Two different programs to achieve an arc absorption microstructure were proposed and studied in experiment.One is realized by air-gap technique,in which one of epitaxy layers is etched by selective chemical wet etching techniques.With the air-gap,the cantilever will bend for the tangential stress and an arc absorption cavity is obtained. The fabrication process of air-gap arc absorption cavity is very simple, but the controllability of angle range and the curvature radius of arc microstructure are not so good.The other is realized by dynamic etch mask technique.With this technique,the angle range of arc microstructure can be controlled by varying the initial and the final concentration of solutions,and the radius of arc microstructure can be controlled by varying the time of titration.A new kind of monolithically integrated photodetector with arc absorption cavity was proposed and demonstrated.2.An optical waveguide reflector based on coupled-triple-microring is designed and analyzed.The reflectivity of the reflector is analyzed and the analytical expression of reflectivity is obtained with transfer matrix method.The simulation results show that the reflection spectrum has multiple peaks,and transmission peaks with very narrow FWHM(～0.02nm) were found in this structure,which are named coupled resonator induced transparency.With suitableκandκ_in,fiat response spectrum can be achieved in this waveguide reflector.3.Minimization of finite-size effects(FSE) in coupled-microring resonator optical waveguide(CMROW) is studied.There are fringes in the transmission spectrum and group delay spectrum for the finite number of resonators in CMROW,which is referred FSE.Finite-size effects can be minimized with the optimized cross-coupling coefficients at both ends of CMROW.The cross-coupling coefficients need to be optimized are obtained with numerical methods for weak coupling and strong coupling respectively.The fitting formulas of the optimized cross-coupling coefficients are obtained according to simulation results.4.A new kind of compound coupled-microring photodetector was proposed and demonstrated.Generally,compound coupled microrings are used to realize Vernier effect.But we found that Vernier effcect can not be achieved if the architecture of compound coupled microrings is symmetrical,and a special transmission spectrum is obtained which is similar to the transmission spectrum of Fabry-Perot filter.A compound coupled-microring photodetector is achieved based on the special spectrum.The response spectrum with larger FSR and smaller FWHM is obtained in this novel coupled-microring photodetector.The mutual restriction between the FSR and FWHM of quantum efficiency in a single-microring photodetector is effectively resolved.5.The monolithically integrated GaAs-based OMITMiC photodetectors, operating at 1.3 um and 1.5um respectively,were designed and fabricated successfully with InGaNAs/GaAs MQWs structure for the first time.At 1298.4nm,a quantum efficiency of 3%with a full width at half maximum of 1nm was obtained.At 1537.6nm,a quantum efficiency of 2.4%with a full width at half maximum of 1.5nm was obtained.