Study On Silicon Photonic Devices Based On The Filter Characteristics Of Microring Resonators

After near50-year rapid development of the semiconductor and microelectronic industry, over10-million logic gates can be interated in a single chip today. However, optoelectronic devices are almost demonstrated by III-V group materials. How to duplicate the great success of the application of silicon in microelectronics and use this indirect-band-gap material to implement the low-cost, high-integration photonic devices is the direction for researchers to make the unremitting efforts.Silicon on Insulator (SOI) has the high refactive index difference, and can be utilized to fabricate the compact photonic devices by CMOS-compatibe process. And the thermo-optic (TO) effect and plasma dispersion effect of silicon can be used to control the SOI-based photonic devices. Microring resonator (MRR), which is constructed by ring and straight waveguides, is a compact optical filter. It is a versatile element used for various applications, such as optical modulators, optical switches, optical add-drop multiplexers, optical routers and sensors.This thesis makes the therotical analysis and demonstration of box-like optical filters, wavelength-selective routers and Fano resonators that based on the filter characteristic of the fundamental element-silicon MRR. The main works are listed as follows:1. The box-like optical filters baed on second-and third-order series coupled10-um microring resonators (MRRs) are designed and demonstrated by the CMOS-compatibe process. The experimental results show that they both realize the box-like filter characteristic. The top of the optical transmission spectrum of the second-order filter’s drop port is very flat with an intraband ripple of0.11dB. The3dB bandwith, insertion loss and extinction ratio (ER) are0.31nm,0.4dB and larger than35dB, respectively. Those of the optical transmission spectrum of the third-order filter’s drop port are0.38nm, less than0.9dB and over39.5dB, respectively. The filter response is successfully tuned by one free spectral range (FSR) through TO effect with a tuning efficiency of48.4mW/nm. The dynamic tuning measurement shows that the filter channel switch time is less than12.63μs.2. The key element of the optical interconnects-optical routers are studied and demonstrated on SOI platform. An eight port optical router is presented as an example to illustrate the design method for establishing an N port non-blocking wavelength-selective router. Then we design and fabricate a four port router with SOI. The possible12I/O routing paths are experimentally observed. Thirteen nonblocking operating states, including four broadcasting states, with worst-case corsstalk of-10dB are supported. By using the comb filter characteristic of MRRs, each path has the ability to route four group wavelengths simultaneously in the measured spectral range, which can increase the data throughput by4times. In order to reduce the device’s crosstalk and insertion loss, a four port router based on two MRRs coupled to crossing waveguide is designed and fabricated. Mearsured results show that the worst crosstalk decreases a lot and is to be around-21.56dB. The insertion loss of some optical paths is reduced about0.61dB. But this structure destroys the MRR’s comb characteristic and can’t realize the simultaneous routing of multiple groups of wavelengths. Hence, another new four port routers based on series coupled MRR box-like filters with the superior performance is proposed.3. The generation principle of Fano resonance is studied and a resonant system that can produce and control Fano resonance is demonstrated on SOI platform. In this system, the Fano resonance originates from the interference of two beams resonant in the MRR. The shapes of the Fano resonances are tunable through controlling the phase difference of the two beams. Both largest slope and high ER are obtained when the phase difference is0.5π or1.5π. Experimental results show that Fano resonances with steep slope and ER over20dB are achieved in the whole FSR by controlling the microheaters to meet the phase condition.