含矽基奈米矽之富矽氧化矽光波導增益研究

A Buried Silicon Nanocrystal Based High Gain Coefficient SiO2/SiOX/SiO2 Strip-Loaded Waveguide Amplifier on the Si Substrate

連承偉(Cheng-Wei Lian)

指導教授 ： 林恭如

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.03200

摘要

在本論文中，我們對 SiO2/SiOX/SiO2/Quartz-substrate 帶狀波導及 SiO2/SiOX/SiO2/Si-substrate帶狀波導做模擬。 在模擬波導的結構時，我們使用了等效折射率法 (EIM) 、光束傳播法 (BPM) 、有限元素法 (FEM) 。 接著，我們製作出這兩種不同結構的波導並利用可變長度法 (VSL) 對一維放大模型公式做曲線擬合，量測其光增益及損耗係數。 我們觀察到內埋奈米矽富矽二氧化矽帶狀波導的自發輻射放光 (ASE) 範圍在 750 - 850 奈米，而其頻譜線寬為 140 奈米。 此外我們得到 SiO2/SiOX/SiO2/Quartz-substrate 帶狀波導的光增益與損耗係數分別為 70 和 5 cm-1 。 而 SiO2/SiOX/SiO2/Si-substrate 帶狀波導的光增益與損耗係數分別為 106.7 和 21 cm-1 。 成長於矽基板的波導元件之光損耗係數較成長於石英基板的波導元件為大，是由於光模態洩漏到矽基板中。 而矽基板波導元件的光增益係數也較石英基板波導元件大，是由於矽基板波導元件具有較佳的光模態侷限。 在小訊號放大實驗中，對於795奈米的雷射小訊號在波長325奈米的氦鎘雷射與激發功率 43.7 毫瓦的條件下，我們在 1 公分的SiO2/SiOX/SiO2/Si-substrate 帶狀波導中得到高達 11.73 dB 的小訊號增益。

關鍵字

奈米矽 ； 波導 ； 光放大器

並列摘要

In this thesis, we simulate the SiO2/SiOX/SiO2/Quartz-substrate strip-loaded waveguide and the SiO2/SiOX/SiO2/Si-substrate strip-loaded waveguide. The Effective-Index Method (EIM), the Beam Propagation Method (BPM), and the Finite Element Method (FEM) are used to simulate the waveguide structure. Subsequently, we fabricate these two type waveguides and measure the optical gain and loss coefficients by fitting the one dimensional amplifier equation of the Variable Stripe Length (VSL) method. We observe that the Si-rich SiOX strip-loaded waveguide with silicon (Si) nanocrystal contributed amplified spontaneous emission (ASE) at 750-850 nm with the associated spectral linewidth of 140 nm is characterized. The ASE spectrum is red-shifted 6 nm to PL spectrum because of mode guiding. The peak wavelength of ASE spectrum is blue shift with longer pumping length. Because of the longer pumping length, the mode guiding is stronger and the peak wavelength becomes stable. The optical gain and loss coefficients of the SiO2/SiOX/SiO2/Quartz-substrate strip-loaded waveguide are 70 and 5 cm-1, respectively. The optical gain and loss coefficients of the SiO2/SiOX/SiO2/Si-substrate strip-loaded waveguide are 106.7 and 21 cm-1, respectively. The optical loss coefficient of the Si-substrate device is larger than the Quartz-substrate device which is due to the optical mode leakage to Si substrate. The optical net modal gain coefficient of Si-substrate device is larger than Quartz-substrate device which is due to the better mode confinement. The small-signal amplification of up to 11.73 dB for 795 nm small laser signal under He-Cd laser pumping of 43.7 mW at the wavelength of 325 nm is obtained from the SiO2/SiOX/SiO2/Si-substrate strip-loaded waveguide amplifier with a length of 1 cm.

並列關鍵字

silicon nanocrystals ； waveguide ； optical amplifier

參考文獻

[1.3] P. Pellegrino, B. Garrido, C. Garcia, J. Arbiol, J. R. Morante, M. Melchiorri, N. Daldosso, L. Pavesi, E. Scheid, and G. Sarrabayrouse, "Low-loss rib waveguides containing Si nanocrystal embedded in SiO2, " J. Appl. Phys., vol. 97, pp. 074312, (2005).

[3.2] P. Pellegrino, B. Garrido, C. Garcia, J. Arbiol, J. R. Morante, M. Melchiorri, N. Daldosso, L. Pavesi, E. Scheid, and G. Sarrabayrouse, "Low-loss rib waveguides containing Si nanocrystal embedded in SiO2, " J. Appl. Phys., vol. 97, pp. 074312, (2005).

Chapter 1

[1.1] L. Dal Negro, M. Cazzanelli, N. Daldosso, Z. Gaburroa, L. Pavesi, F. Priolo, D. Pacifici, G. Franzò, F. Iacona, "Stimulated emission in plasma-enhanced chemical vapour deposited silicon nanocrystals," Physica E, vol. 16, pp. 297-308, (2003).

[1.4] K. Luterová, K. Dohnalová, V. Švrček and I. Pelant, "Optical gain in porous silicon grains embedded in sol-gel derived SiO2 matrix under femtosecond excitation" Appl. Phys. Lett., vol. 84, pp. 3280-3282, (2004).