Military looking for a few good photon chips

The Defense Advanced Research Projects Agency this week issued a call for integrated photonic chip development that would support “fiber-like” losses for optical applications.

The compact chip-scale, integrated photonic (iPHoD) platform will be useful for a wide range of high precision military applications and systems including: high time-bandwidth product analog optical signal processors and delay lines for wideband RF systems, optical buffers for all-optical routing networks, and ultra-stable optical interferometers for sensing applications, such as  rotation sensors, DARPA said.  

The iPhoD program will build the framework of a scalable integrated photonic platform technology that providesfor the handling and manipulation of photons with throughput efficiency and precision approaching that of electrons within electronic integrated circuits.

The iPhoD program is aimed at developing and validating a robust ultra-low loss, single mode, single polarization, compact integrated photonic waveguide technology with accompanying coupler, splitter, and optical technologies. DARPA’s three phase program will demonstrate an ultra-low loss integrated photonic platform capable of scaling to as high as μs-order delays in a small area footprint, and will culminate in a relevant, to-be-proposed, optical delay application demonstration.At present, the transmission loss in state-of-the-art planar optical waveguides and integrated circuits is currently about 1,000 times greater than that found in commercial-grade, silica-based, polarization maintaining optical fibers at telecommunications wavelengths. Hence, the resulting time-bandwidth product available, using any current integrated optical waveguide platform, is orders of magnitude smaller than in fiber. If single channel optical delay lines were all that were desired, fiber delay line processors would probably be satisfactory for most applications.

However, many applications require many high precision parallel fixed or variable delay lines which are not practical with fiber-based operations. Fiber-based devices and arrays are manufactured in a serial process which does not scale to the complex signal processing architectures required for the most compelling applications, DARPA said. Correspondingly, many of the benefits of wideband signal processing that are possible with optical techniques have been largely unrealized, DARPA said.  Fiber-based optical delay solutions can lack the compactness, environmental robustness, manufacturing scalability and precision needed for desired performance and complexity levels.

DARPA said the technical challenges to be addressed in this program include developing the science and technology necessary to fully understand and overcome the important loss contributions in today’s integrated optical waveguides. DARPA solicits the most compelling approaches capable of bridging the gap between optical fiber and integrated optic waveguide transmission losses. Highly flexible efficient input/output optical coupling techniques must be developed that are easily adapted to a variety of coupled devices and mode sizes.

It is anticipated that multilayer 3D routing techniques, utilizing passive optical vias in combination with several layers of planar waveguides, must be developed to achieve the small footprints that are targeted, DARPA stated. Small footprints are a must and have many obvious advantages and some not so obvious advantages including the reduced difficulty of temperature control.

This program seeks a combined analytical and experimental approach, leading to the validation of a comprehensive photonic platform technology suitable for the most demanding military signal routing, processing and storage applications.DARPA is looking to select vendors for iPHoD by July 15, 2008.

Last month DARPA gave Sun a $4 million contract to work on technology to let chips communicate using lasers instead of electricity.  The research will densely pack hundreds of cores in what Sun calls a "macrochip." This research's findings could help data centers reduce power consumption and provide more efficient computational cycles for supercomputers in the high-performance computing space. It could help push supercomputing capabilities in areas like weather research and oil exploration.

Other companies are involved in silicon nanophotonics research. IBM is looking to replace wires on a chip with pulses of light on tiny optical fibers for quicker and more power-efficient data transfers between cores on a chip. The technology transfers data up to a distance of a few centimeters, about 100 times faster than wires, and consumes one-tenth as much power. NEC is also working on technology to enable optical data transmission between chips.  

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Copyright © 2008 IDG Communications, Inc.

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