Research On Photonics Devices Towards Silicon Integration

In the era of modern information society,the emerging technologies including big data,cloud computing,intemet-of-things,artificial intelligence,etc.have very demanding requirement in information transport,process and storage.Silicon based electronics have encountered bottlenecks not only in crosstalk and latency but also in power consumption and heat dissipation.Fortunately,the continuous research of silicon photonic chips can offer an excellent solution to these problems.Silicon material plays an important role in modern optoelectroics integration due to its low costs,CMOS compatibility and transparent in infrared regime.Compared with common SiO2 or LiNbO3 platform,high refractive index contrast of silicon-on-insulator platform makes it possible to reduce the footprint of silicon planar light circuit(PLC),which is of vital importance for large scale integration.Apart from its traditional telecommunication applications,silicon PLC can be used in quantum communication,artificial intelligence,LIDAR and so on.Because of its high quality factor and small mode volumn,optical whispering gallery mode(WGM)resonators have strong light trapping capability and thus enhanced light-matter interaction.They can be found widely in gas sensing,nonlinear four-wave mixing,laser emission cavity optomechanics,etc.This thesis is devoted to the simulation and fabrication of different WGM resonators.The modes and the interaction of these modes in WGM cavities are analyzed theoretically.CaF2 WGM cavities and deformed LiNbO3 WGM cavities are fabricated first and then followed by the monolithic millimeter-scale silicon cavities as well as micrometer-scale silicon sphere cavities.With the on-chip silicon microsphere,a quality factor of 105 can be achieved even at higher order mode coupling scheme.The main context of this thesis includes:1.A summary of analytical and numerical simulation methods develop in recent years and their application in our micro-cavities.2.Introduction of methods used to fabricate the resonators.We have improved the fabricate method for millimeter-scale silicon optical resonators with low sidewall roughness using the CNC precise milling.We have also developed a new fabricate method using green laser annealing for fabricating micro-resonators on chip.3.Disscution of our setup for measuring the aboved mention cavities and the measurement results.Using prism based coupling scheme,we have achieved a high Q factor of 8.22 × 106 for whispering gallery mode in CaF2.In addition,using the tapered fiber,we have achieved a Q of 3.5 × 105 in silicon microspheres for higher order modes.4.A discussion on designing other silicon integrated components and their fabrication results,incluindg spiral waveguide structures,gratings and inverse tapers.