| 摘要: | 高速且高亮度的垂直共振腔面射型雷射（vertical-cavity surface-emitting laser, VCSEL）陣列，能有效降低自由空間光通訊（Optical Wireless Communication, OWC）通道中接收端的繞射損耗，因此在第六代行動通訊（6G）與衛星通訊系統中扮演關鍵角色。相較於邊射型雷射（edge-emitting laser, EEL），如 DFB 雷射，VCSEL通常具備更強的抗輻射能力。然而，傳統設計用於高功率、高亮度與（準）單模輸出的VCSEL，常面臨高相對強度雜訊（relative intensity noise, RIN）以及空間燒洞現象（spatial hole burning effect, SHB）等問題，這些效應會嚴重限制其在高速數據傳輸中的性能表現。
本論文中提出了一種採用新穎環狀鋅擴散（Zn-diffusion）設計與排列緊密的VCSEL 陣列結構，在 850 nm 與 1060 nm 波長下皆可有效克服傳統設計須於單模輸出功率、亮度、RIN 與調變速度之間取捨的瓶頸。與傳統圓形鋅擴散設計的 7×7 850 nm VCSEL 陣列相比，所提出的環狀設計展現出更高的（準）單模輸出功率（160 vs. 145 mW）、更高亮度（73 vs. 65 kW/cm²·sr），以及更寬的-3 dB電光頻寬（22 vs. 17 GHz）。在自由空間傳輸的眼圖量測中，於32 Gbit/s速率下實現無誤碼傳輸且能觀察到清晰的眼圖開口。這些顯著的直流與交流訊號性能表現，歸因於環狀孔徑對於SHB效應的有效抑制。此外，將此環狀孔徑與陣列結構應用至1060 nm VCSEL陣列時，也成功實現了高功率、高亮度與高速傳輸性能，並達成28 Gbit/sec的無誤碼自由空間通訊傳輸。
;High-speed and high-brightness vertical-cavity surface-emitting laser (VCSEL) arrays, which can effectively minimize the diffraction loss in the receiver side of optical wireless communication (OWC) channel, plays a crucial role in the 6G and satellite communications. Compared with the edge-emitting counterpart, e. g., DFB lasers, VCSELs can usually have the stronger radiation hardness. However, the traditional high-power, high-brightness, and (quasi-) single-mode (SM) VCSEL usually suffers the problems of high relative intensity noise (RIN) and spatial hole burning effect, which seriously limit their performances in high-speed data transmission.
In this thesis, Zn-diffusion VCSEL arrays structure with a novel ring-shaped aperture and a compact layout at both 850 and 1060 nm wavelengths are demonstrated to fundamentally overcome the trade-off among the SM output power, brightness, RIN, and modulation speed. Compared with the 7× 7 VCSEL arrays with traditional circular Zn-diffusion aperture at 850 nm wavelength, the new ring-shaped one exhibits higher (quasi-) SM output power (160 vs. 145 mW), higher brightness (73 and 65 KWcm-2sr-1), and a wider 3-dB E-O bandwidth (22 vs. 17 GHz). Clear and error-free 32 Gbit/sec eye-opening over free-space transmission can be measured. These remarkable static/dynamic performances in our array are due to the suppression of spatial hole burning effect in the ring-shaped aperture. Moreover, by implementing the same device structure and layout as those of 850 nm VCSELs array onto 1060 nm ones, similar performances in terms of high-power, high-brightness, and high-speed with error-free 28 Gbit/sec free space transmission have also been successfully demonstrated. |
