矽光子：光柵式耦合器介於光纖及絕緣層上之矽波導

Abstract

隨著時代的進步，資訊量的產生有著爆炸性的成長，人們對於高速網路傳輸的需求也越來越多，電子計算能力以及傳輸同時有著指數性的成長來滿足通訊的需求。然而，電子積體電路的傳輸速率達到了10 GHz的物理極限，這就限制了傳輸速率的提升。現在有著一個嶄新的科技來解決這個問題，我們稱呼他為：矽光子。他整合了光子電路以及電子儀器來用於多工處理，光子電路用於傳輸同時電子電路用於計算，相較於銅導線，光子電路提供高速低耗以及寬頻的通道，這也推動著科技的進步。 光子電路有者以下的元件：光發射源、低耗的波導、高速的調製器、光纖以及矽波導的介面、光邏輯的開關以及光接收器。在本論文中，我們將會著重在光纖以及矽波導的介面，散射光柵式耦合器。 首先，我們會介紹光柵的理論，藉由光柵方程式，我們設計了一維的散射光柵式耦合器。根據模擬的結果，我們計算出耦合效率為40.34%，使用的波長為1550奈米以及39奈米的1dB頻寬。在模擬之後，我們在國家奈米元件實驗室進行元件的製程我們成功的製作出週期為630奈米640奈米以及650奈米的光柵結構，光柵凹陷部分的寬度從270奈米至380奈米並以10奈米為一個間距。蝕刻深度也從80奈米至110奈米。實驗的結果顯示我們最大的耦合效率發生在波長為1572奈米時的21.92%並有著23.4奈米的1dB頻寬。實驗的結果比起模擬的結果相對低落，但是我們在最後與Ghent大學做比較，這樣的結果就還可以接受。 在最後，我們成功的製作出絕緣層上的光柵式耦合器，下一步就是要縮小實驗以及模擬之間的誤差。同時如何達到高效率以及高頻寬的光柵式耦合器是我們未來的目標。

As the time goes on, the generation for information is grown explosively. The need of high-speed transport is increasing for human. The computation power and the transports also grow exponentially to fulfill the need of the communication. However, the transport of the electronic integrated circuit meets the physical limitation for 10 GHz. This limits the improving of the transport speed. Here is a novo technology for solving these problems called silicon photonics. It integrates the photonics circuit and the electronics devices for multiplexing, photonics for communication and electronics circuit for computation. Compare to the copper, the photonics circuit provides the high-speed, low loss, and wide band channel for communication. This will push the improvement of the technology. The photonics circuit should contain the following components: the light source, low loss waveguide, high-speed modulators, the interface between fiber and the waveguide, the logic optical switch, and the photo detector. In this work, we will focus on the interface, diffraction grating coupler, between the optical fiber and the silicon waveguide. First, we will describe the theories of the grating. By applying the grating equation, we design the 1-D diffraction grating coupler as the interface. The simulation result is calculated the coupling efficiency for 40.34% at wavelength 1550 nm with 1 dB bandwidth 39 nm. Besides, we also fabricate the real device at Nano Device Laboratory (NDL) followed by the simulation model. We have successful fabricated the grating structure with the period 630 nm, 640 nm and 650 nm. The width of the grating trench is from 270 nm to 380 nm with 10 nm steps. The shallow etching for 80 to 110 nm is also completed. The coupling efficiency of the experiment result is 21.92% at wavelength 1572 with 1 dB bandwidth 23.4 nm. The experiment result is much lower than the simulation result, but we show the benchmarks which compare to the Ghent University. The number is acceptable. In the end, we fabricated the grating coupler on the real SOI wafer. Next step is reducing the error between the simulation results and the experiments. Furthermore, how to reach high efficiency and broadband grating coupler is the final goal in the future.