Photonics, Optics and Lasers

High-energy lasers (HEL) have the potential to benefit a variety of military missions, particularly as weapons or as high-bandwidth communications devices. However, the massive size, weight and power requirements (SWaP) of legacy laser systems limit their use on many military platforms. Even if SWaP limitations can be overcome, turbulence manifested as density fluctuations in the atmosphere increase laser beam size at the target, further limiting laser target irradiance and effectiveness over long distances.

In the 1940s, researchers learned how to precisely control the frequency of microwaves, which enabled radio transmission to transition from relatively low-fidelity amplitude modulation (AM) to high-fidelity frequency modulation (FM). This accomplishment, called microwave frequency synthesis, brought about many advanced technologies now critical to the military, such as wireless communications, radar, electronic warfare, atomic sensors and precise timing.

DARPA’s Electronic-Photonic Heterogeneous Integration (E-PHI) program has successfully integrated billions of light-emitting dots on silicon to create an efficient silicon-based laser. The breakthrough, achieved by researchers working on the program at the University of California, Santa Barbara (UCSB), will enable the production of inexpensive and robust microsystems that exceed the performance capabilities of current technologies.

DARPA yesterday issued a solicitation for proposals responsive to its Spectral Combs from UV to THz (SCOUT) program, which seeks new capabilities for highly sensitive remote detection of multiple biological or chemical agents in liquid or gaseous forms. A proposers day is set for Oct. 15 via webcast.

The process of detecting light—whether with our eyes, cameras or other devices—is at the heart of a wide range of civilian and military applications, including light or laser detection and ranging (LIDAR or LADAR), photography, astronomy, quantum information processing, medical imaging, microscopy and communications. But even the most advanced detectors of photons—the massless, ghostlike packets of energy that are the fundamental units of light—are imperfect, limiting their effectiveness. Scientists suspect that the performance of light-based applications could improve by orders of magnitude if they could get beyond conventional photon detector designs—perhaps even to the point of being able to identify each and every photon relevant to a given application.