SBIR Phase I: Vertical EML Source for High-Speed Interconnects

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This Small Business Innovation Research (SBIR) Phase I project proposes to demonstrate technical feasibility of a high-speed Vertical Electro-absorptive Modulated Laser (V-EML) for high-speed interconnects. This novel technology is built on the VCSEL (Vertical Cavity Surface Emitting Laser) concept and has all of its nominal advantages such as low-power consumption, on-wafer testability, and possibility of two-dimensional arrays. This technology should eliminate the complications associated with direct modulation of the VCSEL at high speeds. Modulation will be done externally by an electro-absorptive modulator that is integrated with the VCSEL either in a hybrid fashion or monolithically. This approach allows clean modulation without overshoot at speeds higher than 10 Gbps and easily reaching 40 Gbps. Furthermore, by decoupling the modulation issues from VCSEL emission, it provides additional design freedom for achieving extra stability, lower noise and higher reliability. This concept is expected to strongly impact the chip to chip and board to board interconnect industry by virtually removing modulation speed limit and minimizing signal distortion of the optical transmitter.Vertical laser sources in general have cost and size advantages over horizontal emitters in low to medium-power single-device applications. They also lend themselves more easily to two-dimensional array fabrication. The V-EML concept further removes the limitations of direct modulation from these devices. With external modulation, the V-EML can be driven by simpler electronics and at higher speeds. The application that this work is intended for is high-speed interconnects. This can either be in the form of backplane connections, distributed board-to-board connections or chip-to-chip optical interconnects (C2OI). VCSEL arrays known as "smart pixels" have been proposed and tested for such applications. A major impact of this technology is that it will help to remove the chip and board boundaries as significant obstacles to data transport, and will make possible truly distributed and scalable systems of the future. The high-speed interconnects optical communications market size is estimated to be more than $9 billion in 2010.