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標題: | 富碳碳化矽波導中非線性克爾與自相位調變全光開關之研究 All-optical Switching in C-rich SiCx waveguide based on Nonlinear Kerr and SPM effects |
作者: | Cheng-Hsuan Hsieh 謝政軒 |
指導教授: | 林恭如 |
關鍵字: | 碳化矽,環形共振腔,極化,非線性克爾效應,自相位調變,全光開關, SiCx,ring waveguide,polarization,nonlinear Kerr effect,SPM,all-optical switching, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 近年來,為加速實現全光通訊及進一步提升傳輸速率,許多研究學者投入心力發展矽光子學。在此論文中,我們利用了無雙光子吸收效應之富碳碳化矽材料來製作非線性波導,並以材料內之非線性克爾效應及自相位調變為主要研究目標。
首先,利用富碳碳化矽環形共振腔製備高速全光調變器,利用高強度脈衝引發非線性克爾效應實現高速率訊號調變達12.5 Gbit/s,在此研究中,可觀察到富碳碳化矽之非線性折射率約為1.37×10-12 cm2/W,另外,我們發現共振腔之穿透譜會因輸入光極化而改變,透過控制輸入光之極化,可提高環形共振腔穿透譜之消光比與品質因子,並進而優化調變訊號之品質,成功實現12-Gbit/s之全光非歸零開關訊號轉換與反向。 接著,為了提高材料的非線性特性,我們利用了高溫熱退火使富碳碳化矽鍵結重組,經過60分鐘退火後,觀察到材料中sp2鍵結訊號強度增強,預期材料之非線性效應亦隨之增強,相較於未退火時,在相同操作功率下,可觀察到非線性折射率從1.37×10-12 cm2/W提升至2.38×10-12 cm2/W,並同時提升轉換(或反向)後12-Gbit/s全光非歸零開關訊號之消光比、訊雜比及誤碼率。 最後,利用富碳碳化矽材料製備長度為9毫米之長直線波導,並觀察其自相位調變效應,實驗上,我們觀察到光譜縮減,這與常見自相位調變造成光譜拓寬之現象相違背,然而從非線性薛丁格方程式推導發現,當光在波導內傳遞時,負群速度色散與非線性自相位調變之交互作用確實會使光譜縮減,此外,亦發現當改變輸入光之極化時,光譜縮減量會被改變,這主要是因為TE跟TM光在波導內所面對之色散不同而導致,透過非線性薛丁格方程式之模擬,可得出當輸入光譜寬度由6.6 nm縮減至5.05 nm時,其波導色散值為 -10.3 ps2/m。 In recent year, many researcher put lots of efforts on developing silicon photonics to accelerate high-speed transmission and all-optical communications. In this thesis, we demonstrated the nonlinear effect including Kerr effect and SPM by using the TPA-free C-rich SiCx waveguide. First of all, the high-speed all-optical inverter was demonstrated by the C-rich SiCx ring waveguide. The nonlinear Kerr effect induced by intensive pulse performed the high speed modulation. In this work, we found that the transmission spectrum of the ring resonator will affect by the polarization of incident light, which will deterioration the modulated signal. By manipulated polarization of incidence, the extinction ratio (ER) and the quality factor (Q-factor) of the transmission spectrum were improved. We successfully optimized the modulated signal by manipulated polarization. The nonlinear refractive index of the low-temperature PECVD synthesized C-rich SiCx is up to 1.37×10-12. The polarization manipulated all-optical format inversion of 12.5 Gbit/s pulsed return-to-zero on-off-keying (PRZ-OOK) data stream is demonstrated through the nonlinear Kerr switching induced wavelength conversion process. Afterwards, to enhance the nonlinearity, the annealing process was used to regrowth and restructure the C-rich SiCx, which was confirmed by the XPS and Raman analysis. After the 30/60-minute annealing, the graphite-like (sp2-like) C-C bonds are enhanced in the C-rich SiCx film deposited by low-temperature plasma-enhanced chemical vapor deposition (PECVD). With the pumping peak power of 4.3 W, the red-shifted variation of the transmission comb increases from 0.12 nm to 0.14 nm, which reveals that the nonlinear refractive index of C-rich SiCx enhances from 1.37×10-12 to 2.38×10-12 cm2/W with the annealing time increasing from 0 to 60 minutes. Both the 12.5-Gbit/s all-optical data conversion and inversion are successfully achieved. The ER、SNR and BER were optimized after 60-minute annealing. Eventually, the SPM was observed by the 9-mm-length C-rich SiCx channel waveguide. In experiment, we have measured narrowed output spectrum, which is different from the common SPM induced spectrum broadening. In theory, the narrowed spectrum was caused by the interaction between dispersion and nonlinear effect. In addition, with the two orthogonal polarization incidence, the spectrum exhibited different levels of narrow, which caused by the normal and anomalous GVD in the waveguide when propagation different polarization of light. With narrowing the spectrum from 6.6 nm to 5.05 nm, the anomalous GVD of the 9-mm-length C-rich SiCx can be obtained as -10.3 ps2/m with the simulation of the nonlinear Schrodinger equation. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76732 |
DOI: | 10.6342/NTU201601291 |
全文授權: | 未授權 |
顯示於系所單位: | 光電工程學研究所 |
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