Design,Fabrication And Application Of Arrayed Waveguide Grating

With the rapid development of global Internet,the demand of communication capacity and transmission rate is increasing dramatically.Wavelength division multiplexing(WDM)technology has been a key technology to expand the bandwidth of optical communication network.As a typical wavelength division multiplexing device,arrayed waveguide grating(AWG)has lots of advantages,such as compact structure and easy to achieve monolithic integration with semiconductor lasers.Therefore,AWG has been widely used in the WDM systems.In this thesis,designs and applications of AWG are studied deeply.The main work contents can be summarized as follows:(1)The theory of optical waveguide and computational methods are introduced.The working principle,main characterization,theoretical model and design flow of AWG devices are analyzed,which provide the basis for the subsequent design and performance improvement.(2)To reduce the size of AWG and improve the integration,a silicon-based reflective AWG with multimode interference reflectors is proposed.The working principle of multimode interference reflectors is analyzed.By optimizing parameters,a reflector with 0.23 dB loss is designed.After that,by introducing the optimized multimode interference reflectors at the end of the arrayed waveguides,the size of AWG can be effectively reduced for further integration.On this basis,a 1×7 channel silicon-based reflective AWG was fabricated.The adjacent channel crosstalk has decreased for that the crosstalk of conventional AWG and reflective AWG is-7.5 dB to-8.9 dB and-9.6 dB to-12.9 dB,respectively.(3)Another silicon-based reflective AWG with ring waveguide is proposed.The ends of adjacent arrayed waveguides of this reflective AWG are connected to a ring waveguide.In addition,the bandwidth of the device can be doubled theoretically.After completing fabrication and measurement,a reflective AWG can be achieved.Compared with conventional AWG,the 3dB bandwidth is increased from 0.6nm to 1.13 nm.(4)To realize monolithic integration of AWG and lasers,the design of InP-based AWG device is studied.The single mode condition,bending property and the connection structure between straight waveguide and curved waveguide are discussed.And then,a 4×4 channel AWG is designed and fabricated,laying a basis on the subsequent fabrication of InP-based lasers/AWG monolithic integrated chip.In order to improve the tolerance of the laser input wavelength drift,design of AWG with flattop spectral response is studied.By introducing the multimode interference coupler structure at input waveguide,the 3dB bandwidth of the AWG device is theoretically increased to 2.06nm(about 86% channel spacing).