Single-Mode VCSELs With Zn-Diffusion Apertures for Applications in Co-Packaged Optics Systems

High-speed vertical-cavity surface-emitting lasers (VCSELs) with high single-mode (SM) output power and strong immunity to optical feedback play a vital role in further improving the package density in co-packaged optics (CPO) systems. Here, by optimizing the structure of VCSEL cavities with Zn-diffusion apertures inside, we can simultaneously improve the SM output power and speed of 850 nm VCSELs. With this novel structure we can achieve a record-high SM output power of 16 mW and a wide 3-dB electrical-to-optical (E-O) bandwidth of 18 GHz. Furthermore, excellent VCSEL performance can be obtained by varying the aperture size for high-speed operations, such as wide E-O bandwidth (27 GHz), high SM power (6.7 mW), low-RIN (−137 dB/Hz), and invariant 56 Gbps eye patterns under strong optical feedback (−6 dB). Error-free transmission can be achieved at around 48 Gbit/sec through 500 and 200 m multi-mode and single-mode fibers, respectively, without the use of equalizers in the transmission channels.