DARPA’s has a project called Electronic-Photonic Heterogeneous Integration or E-PHI. The program has successfully incorporated billions of light-emitting dots onto silicon thereby creating an efficient silicon-based laser.
Researchers that were working on the program at the University of California, Santa Barbara (UCSB), achieved this breakthrough. It will enable the production of inexpensive and robust Microsystems, which exceed the performance capabilities of technologies that are currently available.
Devices in defense systems, such as radar, communications and imaging rely on a wide variety of Microsystems. These devices normally require particular substrates or base materials and different processing technologies, which are specific to each application. This prevents the integration of such devices into a single fabrication process. Integration of these technologies in the past has required combining one microchip with another, which then introduces significant limitations on bandwidth and latency in comparison to Microsystems that are integrated on a single chip.
DARPA started the E-PHI program back in 2011 with a long-term goal of integrating chip-scale photonic Microsystems with high-speed electronics directly onto a single silicon microchip. Although many photonic components can now be made-up directly on silicon, constructing an efficient laser source on silicon has proven to be difficult. The traditional methods to adding lasers on-chip include separately fabricating lasers on expensive wafers. These then have to be bonded onto silicon chips. It is this conventional bonding process that ramps up the cost of production as it requires extreme precision.
Josh Conway, DARPA program manager for E-PHI said, “It is anticipated that these E-PHI demonstrator Microsystems will provide considerable performance improvement and size reduction versus state-of-the-art technologies…Not only can lasers be easily integrated onto silicon, but other components can as well, paving the way for advanced photonic integrated circuits with far more functionality than can be achieved today.”
In addition to generating light emission on silicon, the UCSB team overcame a common predicament in past efforts to grow non-silicon laser materials directly on silicon called “lattice mismatch.” The UCSB team have proved lasers grown on silicon performed comparably to those which were grown on their native substrate. These results will now be a foundation for the development of other photonic components such as optical amplifiers, modulators and detectors.
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[Image via Darpa]