850nm VCSEL for 112 Gbps NRZ and 200 Gbps PAM4 optical interconnects

The exponential growth in data center traffic driven by artificial intelligence (AI), Internet of Things (IoT), and 5G mobile networks has intensified demand for high-bandwidth, low-power optical interconnects. Vertical-cavity surface-emitting lasers (VCSELs) operating at 850 nm have emerged as the dominant solution for short-reach interconnects due to their inherent advantages in power efficiency, low latency, and cost-effectiveness. Here, we report our work on 850 nm multimode VCSELs to achieve high bandwidth to support single-channel 112 Gbps NRZ and 200 Gbps PAM4, a critical milestone for supporting next-generation 1.6T/3.2T Ethernet standards required by hyperscale data centers. We demonstrate an integrated optical transceiver system achieving unprecedented data rates using high bandwidth and pre-compensation capability of the driver and 850-nm VCSELs with a low relative intensity noise (RIN < -150 dB/Hz). The transmitter-receiver architecture successfully enabled 200 Gbps/lane transmission using PAM4 and 112 Gbps/lane with NRZ with the BER of 1.1×10-4 in back-to-back configuration, representing the ultra-high reported speeds for 850 nm VCSEL-based systems. These results are visually corroborated by clear eye openings observed at near-threshold baud rates, demonstrating exceptional signal integrity despite fiber dispersion effects.