矽基片雙抗諧振反射光波導結構分光元件之設計、研製與特性量測

Abstract

本論文研究矽基片雙抗諧振反射光波導結構分光元件之設計、製作與特性量測，不同耦合長度分光元件的性能亦被探討。對於一個抗諧振反射光波導結構而言，光場藉由在各層之間抗諧振條件被限制於核心層，而在空氣與導光區的界面則藉由全反射來限制。且其可具有較厚的導光區與較低的折射率與單模光纖匹配，因此可有效地與單模光纖耦合。此外，雙抗諧振反射光波導間之耦合效率可以利用調整結構對稱性來控制，因此可依不同需求，設計出符合所需的元件結構。在此研究中，我們利用轉移矩陣法和等效折射係數法來分析及設計抗諧振反射光波導之結構，然後利用波束傳輸法來模擬雙抗諧振反射光波導分光元件之傳輸特性。設計元件兩波導間距為30微米，其耦合長度為4300微米。我們實作元件，其耦合區域長度為1950、2050、2150（半耦合長度）、2250及2350微米，並加以量測特性。雙抗諧振反射光波導分光元件量測結果如下 : 從左邊波導輸入之兩波導輸出之不均勻度差及標準差平均為0.45 dB及0.12 dB，而從右邊波導輸入之值則分別為0.57 dB及0.05 dB。耦合區域長度為2150微米的五個樣品從左邊波導輸入之傳輸損耗分別為3.45、1.95、2.33、1.51及1.88 dB/cm，而從右邊波導輸入之值則分別為2.98、1.27、1.55、2.08及1.84 dB/cm。雙抗諧振反射光波導分光元件製作結果之特性量測，顯示其可有效地分光。

In this thesis, design, fabrication, and characterization of Si-based dual ARROW power splitters are investigated, and the performances of the power splitters with different lengths of the coupling region are presented. For an ARROW structure, light is confined within the core layer by antiresonance conditions in the cladding layers and by total internal reflection at the air-core interface, and it can guide waves in low-index cores with a large core size such that their core index and size can be compatible with single-mode fiber index and diameter to provide efficient coupling with fibers. Moreover, a dual ARROW waveguide can operate as a directional coupler or as two decoupled waveguides by controlling the structural symmetry. Dual ARROW power splitters were realized with ARROW structure in the vertical and horizontal directions. We analyzed and designed ARROW structure with the transfer matrix method (TMM) and the effective index method (EIM). Then, we used the beam propagation method (BPM) to simulate the propagation characteristics of the dual ARROW power splitter. In our devices, we designed the dual ARROW power splitter with a separation width of 30 μm and the coupling length Lc is 4300 μm. We fabricated the devices with the lengths of the coupling region as 1950, 2050, 2150 (Lc/2), 2250, and 2350 μm to verify the design idea. The average imbalance and standard deviation are 0.45 and 0.12 dB by launching a power into the left core of five samples, and 0.57 and 0.05 dB for launching a power into the right core. The propagation losses of five samples for the length of the coupling region as 2150 μm by launching a power into the left core are 3.45, 1.95, 2.33, 1.51, and 1.88 dB/cm, and for the right core are 2.98, 1.27, 1.55, 2.08, and 1.84 dB/cm. Measurement results show that our dual ARROW power splitters can be efficiently realized.