我們將展示垂直共振腔面射型雷射應用於短距離至中距離(2km)於850nm波段具有高度單模輸出、高輸出光功率其細節結構設計。若要進一步的提高資料量與距離乘積比，其高速的提高調製速度與減小動態調製下頻譜半高寬，藉此減少色散是非常重要的。而要製作出單一模態輸出的VCSELs最直接的方式就是將其水氧化孔徑縮小至2?m，但這樣的方式會造成極高的微分電阻(differential resistance)、低輸出光功率( <~2mW)及可靠度方面的問題。輸出光功率是相對重要的，850nm波段在標準光纖內每公里衰減3.5dB的明顯傳輸損耗。不過我們藉由氧化層掏離(Oxide Relief)孔徑和鋅擴散孔徑之前相對大小的最佳化，不需將氧化孔徑微縮至很小，不但能達到高輸出光功率( >6mW)、高單模態輸出， 且達到一個合理的臨限電流(threshold current)( ~1.5mA)。此外我們的方式可以大大降低普遍發生在單模輸出雷射的低頻滾落現象，使最大數據傳輸速率達到26Gbit/sec，且利用OM4-MMF之光纖的傳輸距離達到2 km ，得到一高資料量與距離乘積比為28Gbit km/s (14Gbit/s x 2 km)。 We demonstrate the detail design consideration and fabrication of a highly single-mode, high-power, and high-speed vertical-cavity surface-emitting lasers (VCSELs) at 850 nm for the application of short to medium reach (~2 km) optical interconnect. Reducing the dynamic linewidth of VCSELs under high-speed modulation is essential to minimize the chromatic dispersion and further improve the bit-rate distance product in transmission. Among the reported (quasi) single-mode VCSELs technique, downscaling the size of oxide aperture (~2 um) of VCSELs is one of the most straightforward ways. However, such miniaturized oxide-apertures VCSELs would have a large differential resistance, reliability issues, and a limited maximum single-mode output power (< ~2 mW), which plays an important role in determining the maximum linking distance of fiber with a significant propagation loss at 850 nm wavelength (~3.5 dB/km). Here, by optimizing the relative geometric sizes between the oxide-relief and Zn-diffusion apertures in our demonstrated 850 nm VCSELs, we can not only attain highly single-mode output power (~6 mW) but also sustain the large size of oxide aperture (~9 um) with a reasonable threshold current (~1.5 mA). Furthermore, due to the optimizing of dimension of optical cavity, the spatial hole burning effect induced low-frequency roll-off can be minimized in our proposed structure with a maximum data rate up to 26 Gbit/sec. Record-high bit rate-distance products for OM4 MMF transmission under on-off keying (14 Gbit/sec 2.2 km) modulation formats have been successful demonstrated by use of our VCSEL.
