Processing Improvement Of Arrayed Waveguide Grating (AWG) And Its Monolithic Integration With Photo-detectors

Optical dispersion module is one of the core components in spectrometers.A traditional optical dispersion module is made up of costly grating,lens and CCD sensors.Nowadays,it has become a major challenge to realize a low cost and miniature optical dispersion module,so that the application of spectrometer could be expanded from lab to industries and ordinary life.The arrayed waveguide grating(AWG)is formed by replacing traditional grating and lens with optical waveguide on chip,and realize the same function.While specially designed photo-detector array is able to be prepared on the same chip of AWG substituting for CCD sensors.In this way,the integrating AWG and PD chips are possible to replace the traditional optical module in spectrometer with low cost and tiny size.Raman spectrum analysis is able to identify material composition with"fingerprint" feature.With the advantages of rapid,non-invasive sensing and ability to read multiple chemical molecules in mixture,etc.,it is in strong demand for applications such as food safety detection,environment monitoring and medical diagnosis.However,the traditional Raman spectrometer is costly due to the use of precise optical components and high cost assembly process,which hinders the spreading applications of Raman spectroscopy.A typical Raman spectrometer is made up of a laser device,a Raman prober,and an optical dispersion module.With the development of semiconductor laser chip and photonic crystal,the former two parts can be realized on chip.The chip Raman spectrometer becomes possible if optical dispersion can be implemented on chip.The process improvement of AWG chip,the preparation of a specially designed PD array and the investigation into integration process of AWG and PD,etc.are presented in the dissertation,with the aim of realizing an on-chip Raman spectrometer with 785 nm excited light.The following issues are discussed in individual chapters in the dissertation:1.The AWG layout is designed for the application of Raman spectrometer by using OptiBPM software;2.Process experiments with different parameters on the core layer deposition,mask materials for the core layer etching,thickness of the cladding layer and use of continually in-situ deposition of cladding-core-cladding layers,etc.are carried out to reduce the insert loss of AWG.The optimized process is determined by analyzing the test results of these chips with different process parameters;3.The specialized PD is built according to the output spectrum and beam size of AWG.4.A new process is proposed to realize the integration of AWG and PD on a single chip,and relevant process experiments are carried out.The integration process of AWG and PD has been filed and apply for patents.