SBIR Phase I: 40-100 Gbps VCSEL with Push-Pull Modulation

This Small Business Innovation Research Phase I project proposes to demonstrate a Composite Resonator VCSEL (CRVCL) which will achieve a 40-100Gbps data transmission rate. For more than a decade VCSELs have been the engine driving bandwidth increases at shorter distances (<300 meters) between cabinets in high performance computers, in local area networks (LANs) and storage area networks (SANs), but it appears that conventional VCSEL technology may be running out of steam somewhere between 20 and 30Gbps. The proposed approach is unique in that it avoids the relaxation oscillation limitations on modulation speed through the use of a dual cavity VCSEL operated in a push-pull configuration. The concept dramatically increases the data rate by keeping the current density constant while modulating the light to be emitted from the surface or directed to the substrate. The goals of the Phase I project are to fabricate a CRVCL, demonstrate the push-pull nature of the modulation to a minimum of 20GHz, and demonstrate the elimination or dramatic reduction in relaxation oscillations. If successful, the demonstration of the 40-100Gbps large signal modulation will be proposed for a Phase II project. The broader impact/ commercial potential of this project is to enable the continued expansion of bandwidth within LANs, SANs and between cabinets of high performance computers. In addition, a 40Gbps+ VCSEL will be a breakthrough technology for overcoming the interconnect bottlenecks between boards within a cabinet, and within a board. Copper based interconnects are increasingly the limiting factor in system performance due to their size and power consumption, but the replacement by optical interconnects will require high speed per channel (40Gbps), very low power, high reliability, and low cost. This project concept addresses all four considerations. Higher speed devices feed the bandwidth expansion allowing the continued improvements in business productivity, management of medical information, and entertainment options we have come to expect, and helps maintain the U.S. competitiveness and employment in the networking market. The reduction in power consumption helps achieve the industry and government goals for reducing the power consumption of data centers. The successful development of this technological enhancement will help the U.S. maintain its leading position in the computing and networking industries.