用于传感的聚合物微谐振环的研制

Design and Fabrication of Polymer Micro-ring Resonator Used for Sensors

对一种用于传感的聚合物微谐振环进行了研制。器件为多模耦合器结构,作为微谐振环的输入/输出耦合结构,微谐振环采用跑道形结构。首先分析了器件的原理,给出了器件的优化设计参数。采用紫外光敏材料SU-8和CYTOP作为波导芯层和下包层材料,制作了上述结构的微谐振环器件,并进行了测试。扫描电镜的结果显示,所制备器件的整体形貌比较清晰,波导结构均匀光滑,侧壁陡直度较高。采用截断法测得单模直波导的传输损耗约为2.2 dB/cm。对多模耦合器(MMI)结构和弯曲波导的测试表明,MMI结构在较宽的波长范围内实现了接近50∶50的功分比,且损耗较低,而纯弯曲波导结构的通光性能良好。测量得到的器件谐振输出光谱表明,器件在主谐振峰处的插入损耗约为38 dB,自由光谱区(FSR)约为1.87 nm。通过数据处理分析得到弯曲波导的传输损耗约为5.2 dB/cm。提出了进一步降低器件损耗、改善器件性能的措施。

In this article, a micro-ring resonator for sensing application was investigated, the principle of the device was analyzed, and the optimized parameters were obtained. A racetrack polymer micro-ring resonator, using MMI as input/output coupling structure, was fabricated on silicon chips by lithography technique. Polymer CYTOP was selected as a cladding layer and polymer SU8 as a waveguide layer. The device was tested with a fiber-waveguide precision alignment system In optical measurement, a fiber-waveguide precision alignment system was employed for light couphng, and an infrared CCD camera and an optical spectrum analyzer were used for data acquisition. The SEM results show that the morphology of the device is in good level and the sidewall of waveguides was steep and smooth. The propagation loss of straight optical waveguide was measured to be 2.2 dB/cm. The propagation property of the M MI and the bending waveguide were measured. The result shows that the power ratio of the MMI with low loss is close to 50：50 in the large range of wavelengths, and the transition of bending waveguide is good. An optical spectrum of drop port was gained. The measured results show that the insertion loss of the device is 38 dB and the FSR of device is about 1.87 nm. By analyzing the data, the loss coefficient of bending waveguide is 5.3 dB/cm. The means of reducing the loss of the device and improving the performance of the device is put forward.