Research On The Modulation Performance Of Microring Resonator Modulators

With the development of society and the progress of science and technology, people are in need of communication network with high speed and large capacity. The optical fiber communication technology emerged as the times required. Integrated optical devices are important parts of optical fiber network, and promote the development of optical fiber communication. As a key component in integrated optics, optical modulator is an important part of high-speed and long-distance optical communication network. Microring resonator modulator is widely used in integrated optical devices because of its small size, high integration and low power consumption.The traditional static coupled mode theory is usually used to analyze the microring resonator modulator, but it cannot offer accurate results. It is necessary to develop a dynamic analysis method which can provide accurate results and excellent compatibility with computer programming. Besides, it is important to design a microring resonator modulator that has large bandwidth, low modulation voltage and output signal with high-quality. Combining all the requirements, the main works of this paper are as follows:(1) For the limitation of existing methods to analyze microring resonator modulator, a dynamic analysis method based on signal flow graph is proposed to analyze the dynamic field transmission of a microring resonator modulator by using time discretization and space discretization. As a result, accurate and efficient calculation is achieved.(2) The modulation performance of a single ring modulator is studied. The sinusoidal modulation output, Gaussian pulse modulation output and the modulation depth of coupling strength modulation, refractive index modulation and loss modulation are analyzed. Results show that a large modulation bandwidth and modulation output with high quality can be obtained by using coupling strength modulation. However, the output amplitude attenuation of refractive index modulation and loss modulation is large, so the modulation bandwidth is limited.(3) Coupling strength modulation of a microring resonator modulator with feedback waveguide and microring resonator modulators based on MZI(Mach-Zehnder Interferometer) coupling region are studied. For the microring resonator modulator with feedback waveguide, the sinusoidal modulation output, Gaussian pulse modulation output and the modulation depth of feedback arm modulation, ring modulation and half ring plus feedback arm modulation are analyzed. Results show that refractive index modulation of feedback arm can realize coupling strength modulation. In the case of feedback arm modulation, a large modulation bandwidth can be obtained and the modulation effect is enhanced. In the case of microring resonator modulators based on MZI coupling region, the modulation effect can be enhanced by adding phase rings to the arms of MZI. Modulation performance of a microring resonator modulator without a phase ring, a microring resonator modulator with a single phase ring and a microring resonator modulator with double phase rings are analyzed and compared. A optimization strategy for phase ring is studied. Results show that phase ring can enhance the modulated signal. Modulation performance with high modulation depth and large bandwidth can be obtained by setting the operating point at the resonance point.