IEEE Photonics Society

Boston Photonics Society Chapter

Boston Chapter of the IEEE Photonics Society


April 12, 2007
6:30 PM

MIT Lincoln Laboratory

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Waveguide-Integrated, Antenna-Coupled Tunnel Junction Detectors at 1.5 um

Dr. Philip Hobbs, IBM


Abstract:  Thin film metal-insulator-metal (MIM) tunnel junctions coupled to metal antennas can be used as optical detectors and mixers. This has been known since the early 1990s, and point-contact junctions go back to the 1960s. Antenna-coupled tunnel junction (ACTJ) devices have lots of attractive properties: they're extremely fast, capable of producing RF outputs up to >160 GHz; they have optical bandwidths quite literally from DC to daylight; they're very small, only a couple of square microns, so their capacitances are only a few hundred attofarads; and they work at < 100mV bias. Unfortunately, until now their responsivities have been very low--typically corresponding to ~0.1% quantum efficiency, if not worse, even at long wavelengths.  In this talk, I will present a new class of ACTJ detectors integrated with silicon nanowire waveguides, for use in on-chip and off-chip optical communications. These use multi-metal antennas and a novel plasmonic traveling-wave structure in the junction region, and achieve much higher efficiencies than previous devices. Current efficiencies are a few percent.  We expect eventually to reach ~20% or higher overall quantum efficiency at 1.5 um, which would give these devices speed vs power performance unmatched by any semiconductor device.


Biography:  Phil Hobbs has been a Research Staff Member at the IBM T. J. Watson Research Center for almost 20 years, and has been falling into technological potholes even longer than that.

His research focuses in two main areas:  the application of microwave-style techniques in the infrared for optical interconnection, and bringing ultra-sensitive measurements to cost-sensitive technological applications. He is the author of "Building Electro-Optical Systems: Making It All Work" (Wiley, 2000).  He is the inventor of the laser noise canceller, which allows shot noise limited measurements in bright field with noisy lasers.  He holds about 30 patents, has received both R&D 100 and Photonics Spectra Commercial Technology Awards, and has a successful record in transferring technology to commercial partners and other IBM divisions.  His most recent projects are Footprints, which uses an array of very inexpensive, high performance thermal infrared cameras ( 0.13 K NETD, 96 pixels, $15) to track the motion of people in retail stores, and photonic-plasmonic antenna devices for integrating high-performance optical detectors and modulators in monolithic silicon CMOS technology.


Location:  MIT Lincoln Laboratory