Novel Polarization Contoller Based On Silicon On Insulater In Optical Coherent Communication System

In the development of multi-dimensional hybrid multiplexing technology and silicon-based photonic devices,polarization multiplexing technology could increase the number of communication channels,thus increasing the communication rate and has attracted much attention.Polarizaiton controller is the key component in polarization multiplexing technology.While the devices based on SOI are mostly interesting in the past,it is difficult to improve the chip integration because of the larger size of SOI devices.Surface plasmonic waveguides have drawn much attention because of their significant size reduction.In this dissertation,we expect to study coherent receiver based on surface plasmon polaritonsFirstly,the dissertation introduces the basic principle,development and application of polarization multiplex communication system and coherent optical communication system,and then introduces the optical waveguide theory,the surface plasmonic waveguide theory and the enginmode expansion method,in which the structure and mode characteristics of plasmon polariton waveguides are detailedly discussed to reduce the size of photonic devices,improve the chip integration.In the specific study,the polarization converters based on two kinds of principle and structures are introduced,and a polarization converter using mode coupling based on hybrid plasmonic waveguides is proposed,comprising a Si waveguide,SiO₂ layers surrounding the Si core,and two symmetrically arranged metal strips with respect to the optical axes.By exploiting the mode characteristics of these two hybrid polarization modes,a compact polarization converter is realized.Simulations indicate that polarization conversion is achieved with a polarization conversion efficiency?PCE?of 99.9%,an insertion loss?IL?of 0.82 dB and an extinction ratio?ER?of 30.4 dB at a wavelength of 155 nm for a conversion length of 4.58?m.For the C-band,in a wavelength range of 1530–1565 nm the PCE is greater than 99.6%the IL is below 1 dB and the ER is larger than 24 dB.These performance values are an improvement over those reported HPW-based PCsThen,the working principle and structure of the optical hybrid based on multi-mode interferometer are introduced.The 1×1 MMI?2×2 MMI and 2×4 MMI optical devices based on silicon waveguides is designed by using the self-imaging effect of multimode interferometer?MMI?,besides with optical coherent reciever chip.Further,the dissertation proposes a 2×4MMI optical hybrid based on hybrid plasmon waveguides.For the first time,the effects of high-order modes of hybrid plasmon waveguidess on general interferometric imaging and phase characteristics were analyzed.An industry-standard 90°hybrid was obtained through optimized design,the maximum phase error is less than 1.3°,the maximum non-uniformity is less than 0.6 dB and CMRR is less than-20 dB at the wavelength of 1550 nm.