Studies On Silica-PLC Based Multi-Lane Optical Transmitter And Receiver

Recently,internet of things,cloud computing and smart devices have been developing very fast.The data traffic in the optical communication systems has been growing explosively.To cope with this situation,5G technology and data centers are becoming two hot topics.Optical communication systems are heading towards highly-integrated,low-cost and smart.High-speed optical transmitter/receiver,as core devices in optical communication systems,they are inevitably required to be compactness,low power-consumption and low-cost to meet market expectation.To increase the data transmission capacity,generally,parallel transmission and wavelength-division multiplexing(WDM)technology can be considered,which are based on two different types of optical transmitter/receiver.In contrast,WDM technology is more attractive due to its compactness and low-cost.Until today,domestic research and development of the multi-lane WDM high-speed transmitter/receiver is falling behind.Silica planar lightwave circuit(silica-PLC)based high-speed multi-lane WDM optical transmitter/receiver has gradually been a research hot spot because of its mature process,low-cost and excellent reliability.Meanwhile,III-V components play a very important role in the optical communication systems.To combine the silica-PLC and III-V components for the high-speed optical transmitter/receiver,not only encounters the challenges of design,but also fabrication and testing.In this thesis,with the support of national 863 program,several multi-lane WDM transmitters/receiver based on silica-PLC technology are proposed and demonstrated,including:(1)For 5G RoF analog optical module technology,a low-cost 4-lane coarse wavelength division multiplexing(CWDM)optical transmitter based on silica-PLC arrayed waveguide grating(AWG)is proposed and demonstrated.For cost-effective,a flexible printed circuit(FPC)is employed to connect the interior and the exterior of the transmitter for radiofrequency signal transmission instead of the conventional costly ceramic feed-through box.Furthermore,a commercial aspheric lens is utilized to couple the light from distributed feedback laser diode(DFB-LD)to the waveguide of the silica-PLC,and the coupling efficiency is around-3 dB.Moreover,the design and packaging process of the transmitter is investigated deeply.At last,the fabricatedtransmitter is characterized by installing it on an analog optical module.The packaged transmitter is validated to achieve error-free transmission for 15.5 km single mode fiber.(2)In terms of 100 G CWDM4 QSFP28 optical module application,a low-cost and high tolerance 4×25-Gb/s optical transmitter based on two-lens optical coupling between the silica-PLC and DFB-LD has been proposed and demonstrated.Similarly,a FPC and a non-hermetic metal box are introduced instead of the conventional costly ceramic feed-through box.Furthermore,to relax the process accuracy requirement,a two-lens optical coupling configuration is proposed.According to both simulation and experiment,the alignment tolerance of all lenses can be enhanced greatly.Then,the fabrication process of the optical transmitter is explored in detail.Finally,the performance of the developed optical transmitter is evaluated.The packaged optical transmitter is proved to achieve a 10 km single mode fiber error-free transmission with a bit rate of 25.78125 Gb/s for each lane.(3)The compactness of the optical transmitter/receiver has been always pursued for the data center application.We propose and demonstrate a miniature 4-lane WDM optical transmitter based on butt-coupling between the DFB-LD and silica-PLC AWG.For the traditional butt coupling schemes,a trade-off is existing between the coupling efficiency and back reflection.To overcome this,a novel butt coupling configuration is proposed.Firstly,the structure design and alignment tolerances of the proposed butt coupling scheme have been investigated through both simulation and experiment.Then,the transmitter is designed and fabricated.At last,we evaluate the packaged optical transmitter.According to all the measurements,we can conclude that the developed optical transmitter is a good candidate for 100 G CWDM4 QSFP28 module up to 10 km transmission.(4)For 100 G CWDM4 QSFP28 optical module,a low-cost 4×25-Gb/s WDM optical receiver based on silica-PLC facet total reflection is proposed and demonstrated.We firstly propose the structure of the receiver.Then,we calculate the coupling efficiency and alignment tolerances between the photodetector and silica-PLC AWG.Furthermore,the mechanical design of the receiver is completed.The fabrication process of the receiver is investigated,thus a receiver is packaged.At last,the developed receiver is evaluated.According to the testing,the developed receiver can be used for 100 G CWDM4 QSFP28 optical module.