SBIR/STTR Award attributes
The development of a VCSEL capable of 100Gbps NRZ signaling over the temperature range of -40 to +85C with photonic resonant enhancement of the modulation bandwidth using photonic crystal coupling is proposed. A revolutionary change to the recent evolutionary progress in high speed VCSEL operation is needed to make the leap from 25Gbps devices to ones capable of delivering the > 60GHz bandwidth needed to operate NRZ at 100Gbps. Previous efforts have focused on traditional scaling of the active volume, parasitic reduction, and reducing the cavity lifetime. These methods all lead to VCSELs with inherent reliability and power limitations. The PC-VCSEL proposed here utilizes a simple manufacturing process and has inherently high reliability and scalable power output. The design approach does not require an oxide aperture to provide current and optical guiding, thereby reducing the incurred crystal stress and enabling the use of binary AlAs mirrors to increase the thermal conductivity of the device. Both of these factors work to increase the available output power and improve reliability. To date, demonstrated PC-VCSELs have achieved more than 37GHz of optical bandwidth and have operated links error free to more than 40Gbps NRZ (bot test equipment limited). The proposers have also previously demonstrated links up to 104Gbps NRZ using highly engineered electrical wave shaping and error correction techniques using traditionally scaled VCSELs. The PC-VCSEL proposed here have two coupled cavities that can be driven independently and the possibility of tailoring the driving waveforms (phase and amplitude) independently introduce a new control possibility. The design and implementation of an engineered electrical signal is a requirement for achieving reliable 100Gbps operation. Another unique benefit of the PC-VCSEL technology approach is that it is independent of emission wavelength. PC-VCSELs can be made to operate from 850nm to more than 1050nm, matching the available high bandwidth multimode optical fiber and the Short Wavelength Division Multiplexing (SWDM) window. Single transmitters will operate at 100Gbps NRZ, and a 20nm spaced wavelength grid would provide 1Tbps in a single fiber. While 100Gbps operation may be achievable with lower bandwidth lasers using more complex signaling and error correction techniques (PAM4, etc.), NRZ signals are inherently lower power consumption per bit and provide the lowest system latency. Both of these factors are critical in the deployment of future data centers and high-performance computing centers. With more than 500M VCSEL based optical links in the world today, VCSELs are the workhouse of data communications, but a paradigm shift in VCSEL design is needed to reliably operate at 100Gbps NRZ. This proposal brings together revolutionary VCSEL technology, world class electrical wave shaping and link engineering, and a team with a proven record of high volume commercial VCSEL success.
