Abrupt Waveguide Bend of Buried Hybrid Polymer Waveguides Using Fresnel Refraction

• Main Authors: Yieh-Ter Huang, 黃亦德
• Other Authors: A. K. Chu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/87005654715098653720

碩士 === 國立中山大學 === 光電工程研究所 === 89 === Abstract A buried hybrid waveguide with large angle bend utilizing Fresnel refraction is presented. The waveguide device consists of a polymer core buried in SiO2 cladding on a Si substrate. Large angle bend of the waveguide is achieved based on Fresnel refraction by inserting a low index region into the bend structure. The buried hybrid waveguide was fabricate by dry etching a trench into the SiO2 cladding using Cr as the etch mask. Benzocyclobutene (BCB) polymer was then coated on to the sample to planarize the surface and was used as the guiding core. Etch back was performed to remove the polymer outside the guiding region. The device was completed by passivating the surface with a thin layer of spin on glass (SOG). The normalized transmission loss of the hybrid waveguide with two 8° angle bends is 75%. The propagation loss of the waveguide is 0.6 dB/cm. In addition, a theoretical model of the bend waveguide is proposed. BPM-CAD is used to calculate the bending loss of the waveguide with different bending angles. The calculated results suggest that a large angle bend can be obtained for a large index different the core and the cladding.