Silicon-Based Multi-Channel Optical Sensors With Cascaded Ring-Resonators

The integrated optics has been contributing much to the optical interconnects and intellegent sensing.Among the members of the integrated optics, the silicon nano-waveguides and devices have explosive development as its advantages of ultracompact footprint, high-density integration and compatibility with the CMOS technology. The microring resonator is a popular integrated devices as its advantages of simply fabricaion, low insert loss, field enhancement and no need of reflector, is widly used in optical communication, optical sensor technology,optical-biotechnology and so on.This thesis focus on the need of optical sensors,and most importantly, a novel multi-channel cascaded-ring sensor is introducted, designed, and fabrication and performance test are done.The thesis is beginning with a theoretically investigated the optical microcavitis based on SOI nanowire. By combining the finite difference time domain method and the transfer matrix method, we discuss how coupling parameters influence the coupling ratio. Based on the coupling between straight waveguide and microring, we design a 1xN wavelength-selective optical power splitter, and it's flexible to change the parameters of the coupling area to reach an arbitrary power splitting ratio.Then, the cascaded ring structure is combined with the theory of 1xN wavelength-selective optical power splitter, to realize a novel multi-channel cascaded micro-ring sensor based on silicon. The sensor in this structure has an ultra high sensitivity because of Vernier effect (at the level of 105 nm/RIU), and this design will be useful to realize the spectrum analysis with low-resolution integrated spectrum analyze, and also make it able to sensing units combine with spectrum analyzing units in single chip, and to build the optical sensing on-chip system. This thesis also analysis the temperature sensitivity of the cascaded micro-ring sensors structure, and the result shows by optimizing the structure parameters of the waveguide, the temperature sensitivity of the micro-ring sensor can be reduced significantly.