VCSEL Based Low Power 250Gbps Optical Transceiver

Vertical Cavity Surface Emitting Lasers (VCSELs) have been the workhorse for high bandwidth and low power consumption data links in modern data centers and more recently in AI computing. They have also proven robust in harsh radiation environments like the Large Hadron Collider and have also been deployed in several space programs. However, with recent increases in the data rates needed for in these applications, compromises in temperature range and packaging have been made to reach the cost and performance targets in standards driven applications. This has led to a lack of critical optical components for strategic military and space applications. To address these issues, Photon Sciences has developed VCSELs and photodetectors capable of more than 25Gb/s at wavelengths at 850, 895, 940, and 985nm for use in 100G military applications. This proposal increases the fundamental speed of these VCSELs 64Gb/s per channel. To improve reliability for space-based applications, the 850nm VCSEL is replaced with a 1030nm VCSEL. Together these form a Short Wavelength Division Multiplex (SWDM) link operating on OM5 optical fiber capable of meeting the prescribed 250Gb/s aggregate bandwidth, radiation hardness, and energy per bit of this solicitation. The principal advantage to the SWDM architecture transmission on a signal fiber resulting in reduction of size and weight of the cabling. It is natural to extend the 980nm VCSEL to a 1x4 array compatible with parallel ribbon fiber-based transceivers that are widely deployed. The companion photodiode uses a metamorphic GaAs based structure that achieves quantum limited responsivity across the entire SWDM spectrum. The VCSELs operate uncooled over the entire operating temperature range and the total power consumption of each VCSEL is approximately 10mW, with only 6mW of heat dissipation, resulting in less than 0.2pJ/bit at 64Gb/s. Commercial laser drivers and CDR components have been previously optimized for low power consumption and are expected to meet the 5pJ/bit target at 64Gb/s. In phase 1, 50Gb/s components currently in fabrication will be tested and the design further refined to achieve 64Gb/s operation and ported to 980nm; a 1030nm VCSEL will be designed and epitaxial material will be procured; and the metamorphic photodiode will be refined to achieve 64Gb/s. A quick turn process will be used to confirm the electro-optical characteristics of the VCSEL, and initial measurements of bandwidth will be made. Photon Sciences Incorporated will partner with Ultracomm Commercial to put the VCSELs and detectors in high-speed transceivers based on their space qualified chip-scale packaging. When compared to other technologies, uncooled and directly modulated VCSEL offer the lowest power consumption and the inherent radiation tolerance make the choice of VCSEL based components for this solicitation clear.