Polymer Tunable Micro-Ring Resonator And Its Time-Delay Characteristics

Optical waveguide micro-ring resonator has the advantages such as small size, good filtering property, easy for integration. And a variety of integrated functional devices such as filters, lasers, modulators, optical switch, optical delay line and waveguide sensors can be realized based on the waveguide micro-ring resonator. Organic polymer materials with simple fabrication processes, high thermal coefficients and low costs are widely used in the field of integrated optical devices. Here the working principle, structure design, manufacture process, tuning characteristics and time delay of polymer micro-ring resonator were studied.In this thesis, the racetrack type polymer micro-ring resonator was designed and optimized. Single mode waveguide based on the inverted ridge cross-section was chosen and the effects of the bending radius, gap coupling, coupling length and electrode structure parameters on the device performance were studied. The spectral characteristics of the device was analyzed by the beam propagation method and the optimized structure parameters were obtained. The inner ridge height is 1.8?m, core layer slab thickness is 1.1?m, the outer ridge height is 0.7?m, coupling gap size is 1.5?m, coupling length is 300?m, bending radius is 1500um. By using the polymer ZPU-44 as the cladding layer material and the polysulfone (PSU) as core material, the device was fabricated by the micro-fabrication processes such as the spin coating, lithography, reactive ion etching. In addition, the test results of the device show that around the wavelength of 1550 nm, the free spectral range (FSR),3 dB bandwidth and quality factor Q of the device are 0.15 nm,0.0235 nm,6.60*104, respectively. What's more, the extinction ratio of the device can be tuned from 0.5dB to 12.95dB in the voltage range from 0V to 4V. And only 4.75 V is needed to tune the resonant wavelength of the micro-ring resonator across a free spectral range, the maximum time delay is about 1.08ns. And an optimized scheme based on the Mach-Zehnder interformeter coupled with micro-ring resonator was proposed because of the temperature drifting problem of the direct coupling type micro-ring resonator (straight waveguide is coupled with micro-ring resonator directly). The device was designed, fabricated and tested. Test results show that the extinction of the improved device is 3.15dB higher than the direct coupling type device and the temperature drift problem is improved.Experimental results show that the device has good thermo optic tuning characteristics, high Q value and·good delay characteristics, and the device has the advantages of compact structure and simple fabrication process. The device has a great potential on the optical filter, optical modulator, optical waveguide sensors and tunable optical delay devices.