同調耦合彎折B型抗諧振反射光波導之設計、研製與特性量測

Abstract

本論文研究同調耦合彎折B型抗諧振反射光波導(ARROW-B)，包括其設計、元件製作與特性量測。B型抗諧振反射光波導結構可傳輸橫向電場偏極化(TE)及橫向磁場偏極化(TM)的基模光波，具有較大的入射導光區，可與單模光纖有效耦合。同調耦合效應發生在具有多段的彎折結構，由於每段長度會影響到能量傳輸效率，各段長度適當選擇可於彎折波導有效傳輸光訊號。本研究利用多層膜傳輸矩陣理論和有效折射係數法來分析及設計B型抗諧振反射光波導結構，並以波束傳輸法來模擬彎折結構特性，設計了在矽基片上將光橫向偏移500微米、總彎折角度為4.8度及8度的彎曲波導。總彎折角度為4.8度時，TE模態和TM模態的彎折傳輸效率分別為0.722 (1.41 dB)和0.763 (1.17 dB)；總彎折角度為8度時，TE模態和TM模態的彎折傳輸效率分別為0.642 (1.92 dB)和0.718 (1.44 dB)。實際製作出所設計的元件，量測其總彎折角度為4.8□時，TE模態和TM模態的彎折傳輸效率分別為0.398 ~ 0.435 (3.62 ~ 4.00 dB)和0.415 ~ 0.484 (3.15 ~ 3.82 dB)；總彎折角度為8□時，TE模態和TM模態的彎折傳輸效率分別為0.332~0.382 (4.18 ~ 4.79 dB)和0.385~0.410 (3.87 ~ 4.14 dB)。

In our investigations, we design the ARROW-B based bending waveguides with the total lateral shift equaling 500 μm by coherent coupling effect. The ARROW-B structure can guide light with the fundamental mode of TE and TM polarizations. The large core size can provide efficient coupling with single-mode fibers. Coherent coupling effect occurs in a bending structure of successive sections. Due to the influence of the interconnection length on power transmission efficiency, proper length should be chosen to obtain a high transmission efficiency. The transfer matrix method and effective index method were used to analyze the ARROW-B structures. The beam propagation method was used to simulate the performance of the bending waveguide. Finally, we designed the ARROW-B based waveguides with 0.8°×10 and 0.8°×6 bending angles at the operating wavelength 0.6328 μm. The designed bending transmission efficiency of TE and TM modes are 0.722 (1.41 dB) and 0.763 (1.17 dB) for the total bending angle equaling 4.8°; 0.642 (1.92 dB) and 0.718 (1.44 dB) for the total bending angle equaling 8°, respectively. After fabrication and measurement, the measured bending transmission efficiency of TE and TM modes are 0.398 ~ 0.435 (3.62 ~ 4.00 dB) and 0.415 ~ 0.484 (3.15 ~ 3.82 dB) for the total bending angle equaling 4.8°; 0.332 ~ 0.382 (4.18 ~ 4.79 dB) and 0.385 ~ 0.410 (3.87 ~ 4.14 dB) for the total bending angle 8°, respectively.