富矽碳化矽微米環波導之全光調變

Abstract

近年來，在矽光子積體光學中運用四族半導體材料來達到高速資料處理與傳輸已經吸引了許多關注。在本文中，製備了富矽碳化矽薄膜來分析其材料特性與製備微米環波導元件，並藉由雙光子吸收誘發自由載子吸收機制，進一步達成全光波長轉換強度調變的訊號處理。在第2章中，運用了雙光子吸收誘發自由載子吸收機制，在富矽碳化矽微米環波導中首次進行正交振幅調變-正交分頻多工訊號(QAM-OFDM)的全光調變。將調變頻寬由100 MHz 增加至 1.5 GHz時，經由波長轉換後的4-QAM OFDM訊號可通過前向錯誤更正碼的標準，其訊雜比、誤差向量幅度以及位元誤碼率分別為9.49 dB、1.4×10-3 以及33.5%，使得全光調變速率可以達到3 Gbit/s。在第三章中，利用了正交振幅調變-正交分頻多工訊號(QAM-OFDM)以及通用濾波組多載波處理(UFMC)，於富矽碳化矽直線波導中運用自由載子吸收機制進行波長轉換的訊號調變，並且比較了頻寬分別在1.2 GHz與1.5 GHz的前端放大時，載有8-QAM UFMC的訊號可分別達到傳輸速率為3.6 Gbit/s以及4.5 Gbit/s，且其訊雜比/位元誤碼率分別為12.3 dB/2.9x10-3以及12.2 dB/3.3x10-3，皆可以滿足前向錯誤更正碼的標準。在第四章中，首次利用了多頻帶的正交振幅調變-正交分頻多工訊號(QAM-OFDM)以及通用濾波組多載波處理(UFMC)，經由富矽碳化矽直線波導中的自由載子吸收機制，使得全光波長轉換的訊號調變速率可以達到7.2 Gbit/s。在1.2 GHz以及1.4 GHz的可使用頻寬下，頻帶分別被分段成6段與7段以自由載子吸收機制於富矽碳化矽直線波導中進行調變，經由分析接收到的在每個頻帶下的訊號，其全光調變速率分別可以達到5.6 Gbit/s與7.2Gbit/s。相較於傳統寬頻的傳輸，平均的訊雜比整體提升了約5~6 dB。經由運用此多頻帶的QAM-UFMC訊號，可以更加有效利用富矽碳化矽直線波導中的自由載子吸收的有限頻寬，進一步提升訊號傳輸的容量。

Developing the group IV semiconductor material in silicon photonics integrated circuits has obtained a lot of attraction for the high-speed data switching, processing and transmission in recent years. In this thesis, the silicon excessive SiCx based micro-ring resonator waveguide was simulated, fabricated and analyzed to achieve all-optical intensity modulation wavelength conversion by two-photon absorption (TPA) induced free-carrier absorption (FCA).In Chapter 2, the all-optical cross-wavelength quadrature amplitude modulation orthogonal frequency-division multiplexing (QAM-OFDM) data switching in the silicon rich silicon carbide (Si-rich SiC) micro-ring (m-ring) waveguide is demonstrated for the first time by using the two-photon absorption (TPA) induced free carrier absorption (FCA) process. With enlarging allowable the 4-QAM OFDM data bandwidth to 1.5 GHz, the wavelength-converted probe data can successfully satisfies the FEC criterion with qualified SNR, BER and EVM of 9.49 dB, 1.4×10-3 and 33.5%, respectively, making the all-optical switching data rate approaching 3 Gbit/s. In Chapter 3, the all-optical 8-QAM UFMC pump-to-probe wavelength conversion via TPA induced FCA mechanism in the Si-rich SiC bus waveguide is demonstrated. Under the 1.2-GHz and 2.5-GHz wideband pre-amplification, the converted probe carried with 8-QAM UFMC data can be respectively achieved up to 3.6 and 4.5 Gbps with their SNR/BER of 12.3 dB/2.9x10-3 and 12.2 dB/3.3x10-3, both satisfying the FEC criterion of 12.04 dB/3.8x10-3. In Chapter 4, the high-speed free carrier absorption mechanism in Si-rich SiC bus waveguide is employed to demonstrate the all-optical wavelength-converted switching of multi-band bit-loading QAM-UFMC data at 7.2 Gbps. Pre-amplifying the bit-loading QAM UFMC data at allowable bandwidth of 1.2/1.4 GHz achieves a receiving raw data rate of 5.6/7.2 Gbit/s when performing the pump-to-probe conversion in the Si-rich SiC waveguide by slicing into six/seven bit-loaded sub-bands. In comparison with the typical wideband 8-QAM UFMC data, the average SNR of the bit-loaded 16-64 QAM UFMC data is greatly enhanced by at least 5-6 dB under 2.5 GHz wideband electrical pre-amplification. These observations reveal that the discrete sub-band bit-loading M-QAM UFMC format can greatly improve the data transmission capacity of the TPA-FCA induced wavelength conversion in the Si-rich SiCx bus waveguide, which fully use the finite FCA bandwidth to switch the data at high bit rate in the Si-rich SiC waveguide.