Integration of Planar Lightwave Circuit and Photonic Crystals

• Main Authors: Lung-wei Chung, 鍾隆維
• Other Authors: San-Liang Lee
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/9988y3

博士 === 國立臺灣科技大學 === 電子工程系 === 94 === In this thesis, we are interested in the integration of planar lightwave circuit and photonic crystals. Both analysis and design are based on the application of passive devices in optical passive network. The major wok includes three parts. Firstly, we present a novel design of dual-band demultiplexers based on a periodic hexagonal lattice of holes or rods on silicon materials. The demultiplexing function can be applied by coupling between two defect waveguides at one wavelength and with decoupling then at another wavelength. Appropriately choosing the radius and number of separated rows yields a broad bandwidth for one range of wavelengths. Two designs that use rods or holes to generate photonic crystals are realized. Secondly, a unified method was proposed to reduce the beat length of a multimode interference (MMI) coupler. By properly adjusting the phase difference of the N-fold images, the mode evolution is changed to generate self-images at a much shorter distance. The effect of adjusting the phase difference can be regarded as dividing the original MMI coupler into multiple sub-MMI couplers. Such an effect can be applied for both symmetric- and paired-interference cases. We applied the principle to design compact optical splitters operating at dual wavelength bands. The simulation shows that excellent performance with reduced coupler length can be obtained for splitters operating at both 1.3 and 1.55 um bands. Thirdly, by the combination of multimode interference and photonic crystals, a broad-band 1.3/1.55-um demultiplexer can be realized with a very compact structure. Simulation with the finite-difference time domain method shows its excellent performance. Greater than 20dB an isolation ratio and the insertion loss less than 3 dB over 100nm bandwidth at both wavelength bands are obtained.