導波矽光學平台於光學連接之研究

Research on Guide-Wave Silicon Optical Bench for Optical Interconnect

張家齊(Chia-Chi Chang)

指導教授 ： 伍茂仁

國立中央大學/理學院/光電科學研究所/博士(2012年)

摘要

本論文概念為發展應用於光連接之導波矽光學平台。其研究重心在如何透過帶有45度微反射面之光波導，將封裝於矽光學平台上之主動元件進行光學的非共平面耦合。而導波矽光學平台可以分為兩種模式：(i) 基於SOI基板之矽梯形波導，以及(ii) 基於矽基板之聚合物波導。在矽梯形波導研究中，使用1310 nm光源在所提出的SOI矽光學平台中，首次驗證三維光路連接SOI基板上之非共平面。而在聚合物波導的研究中，則是首次驗證 850 nm 光源可以被應用於矽基板之光連接技術上。
聚合物波導整合45° 微反射鏡之矽光學平台已被驗證，且可利用於傳輸波長為850 nm之光源。提出的架構之耦合效率為 -2.5dB，而聚合物波導的傳輸損耗為0.35 dB/公分。在週期為 250 μm的多通道傳輸應用，其通道間串音干擾可以達到-40 dB的水準。另外，聚合物波導可同時連接兩個矽基45度微反射面，此提出的架構可以發展成為垂直性分光元件。其結果驗證，可在兩個不同的輸出端測量到光強度分別為-6.8dB 和 -5.6 dB。其分光率大約為 3:2，¬而此垂直性分光元件總插入損耗約3.92 dB。
另一方面，矽波導型結構採用SOI作為基板。其SOI波導結合矽基45度反射面被驗證應用在三維非共平面光連接上。此提出之SOI矽波導光學平台可以應用於波長大於 1100 nm 的光源，而本研究採用1550 nm光源作為驗證光源。提出的架構之耦合效率為 -4.51dB，而SOI波導的傳輸損耗為0.404 dB/公分。此架構在1-dB位移誤差有超過 ±20 μm的容許值可以應用，另外通道間的串音干擾可低至-53 dB。相同的，SOI波導架構亦可發展為垂直性分光元件。其分光元件總插入損耗約在3.5 to 3.9 dB之間。而分光比例可以藉由調整SOI波導寬度，本研究實際驗證分光比例控制在大約為4:1, 2:1, 和1:1。
最後，矽波導型的SOI矽光學平台實際應用並製做成光連接的發射模組。面射型雷射採用倒晶封裝技術直接封裝在矽光學平台上，並實際的傳輸5 Gbps之高速訊號。 量測結果可以得到一個清楚的 5Gbps 眼圖。由此可證實此三維的矽光學平台可以有效的耦合面射型雷射並傳輸高速訊號。所得到之結果可應用並發展晶片內部光學連接。

關鍵字

導波矽光學 ； 光學連接 ； 三維光路

並列摘要

In this dissertation, the concept of guided-wave silicon optical bench (GW-SiOB) is proposed for optical interconnects. The research focuses on developing optical waveguides with 45° micro-reflectors for out-of-plane coupling as the active devices being assembled on silicon optical bench. The GW-SiOB can be classified into two groups, optical waveguides of (i) silicon trapezoidal waveguides based on silicon-on-insulator (SOI) substrate, and (ii) polymer waveguides based on silicon substrates. In the silicon trapezoidal waveguide case, the three-dimensional (3-D) optical paths interconnect the front and rear facets of SOI substrate using the 1310-nm light wave is demonstrated the first time. In the polymer waveguide case, the 850-nm light wave can be applied to optical interconnects on silicon substrates for the first time.
The polymer waveguides embedded in the SiOB with 45° micro-reflector using the laser beam of 850-nm wavelength is demonstrated. The coupling efficiency of the proposed structure is -2.5 dB and the propagation loss of polymer waveguide is 0.35 dB/cm. For multi-channels application, the channel pitch for the waveguide array is 250 μm. The cross talk of channel-to-channel could be suppressed down to -40 dB. The polymer waveguides combined with silicon-based 45° micro-reflectors are also realized on a silicon substrate to demonstrate a vertical splitter with out-of-plane output ports. Its transmission efficiencies are -6.8 and -5.6 dB, respectively, for two output ports. The split ratio of proposed splitter is around 3:2. The total insertion loss of proposed splitter is estimated as 3.19 dB. The first output port can be placed a photodiode to monitor the power of input port.
On the other hand, the SOI-based trapezoidal waveguide with a 45° micro-reflector is realized to demonstrate a 3-D bending for non-coplanar optical interconnects. The proposed SOI-based SiOB can apply to wavelength over 1100 nm. The transmission efficiency of proposed structure with wavelength of 1550 nm can be controlled at the level of -4.51 dB, and the propagation loss of SOI waveguide is 0.404 dB/cm. The wider alignment tolerance of ±20 μm is achieved to facilitate the system assembly. The multi-channel trapezoidal waveguides are also demonstrated to verify the cross talk of channel-to-channel as low as -53 dB. The vertical power splitter based on guide-wave SiOB with 45˚ micro-reflector is also realized to demonstrate a 3-D silicon photonics. This guide-wave power splitter has two Si-based 45˚ micro-reflectors, one is utilized to bend the light beam into SOI waveguide, and the other separates partial power to monitor the power of laser or be a variable optical path. The total insertion loss of proposed splitter is around 3.5 to 3.9 dB. The power split ratio can be controlled by modulating the width of waveguide and the split ratio with around 4:1, 2:1, and 1:1 have demonstrated in this research. The wider alignment tolerance of proposed splitter is more than the present assembly technology (±5 um) and achieved to facilitate the system assembly.
Finally, a SOI-based optical interconnect transmitter with trapezoidal waveguides and 45° micro-reflectors is demonstrated. The trapezoidal waveguides monolithically integrated with 45° micro-reflectors facilitate a 3-D bending for non-coplanar optical interconnects. It would simplify and shrink the intra-chip optical interconnect located on a silicon substrate. The clearly open eye patterns at 5-Gbps data rate verify the proposed guide-wave SiOB is suitable for intra-chip optical interconnects.

並列關鍵字

three-dimensional optical path ； guide-wave silicon optics ； optical interconnect

參考文獻

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