Novel Sensing and Detection

The U.S. Military relies on the space-based Global Positioning System (GPS) to aid air, land and sea navigation. Like the GPS units in many automobiles today, a simple receiver and some processing power is all that is needed for accurate navigation. But, what if the GPS satellites suddenly became unavailable due to malfunction, enemy action or simple interference, such as driving into a tunnel? Unavailability of GPS would be inconvenient for drivers on the road, but could be disastrous for military missions. DARPA is working to protect against such a scenario, and an emerging solution is much smaller than the navigation instruments in today’s defense systems.

Microelectromechanical systems, known as MEMS, are ubiquitous in modern military systems such as gyroscopes for navigation, tiny microphones for lightweight radios, and medical biosensors for assessing the wounded. Such applications benefit from the portability, low power, and low cost of MEMS devices. Although the use of MEMS sensors is now commonplace, they still operate many orders of magnitude below their theoretical performance limits. This is due to two obstacles: thermal fluctuations and random quantum fluctuations, a barrier known as the standard quantum limit.

It is difficult to imagine the modern world without the Global Positioning System (GPS), which provides real-time positioning, navigation and timing (PNT) data for countless military and civilian uses. Thanks in part to early investments that DARPA made to miniaturize GPS technology, GPS today is ubiquitous. It’s in cars, boats, planes, trains, smartphones and wristwatches, and has enabled advances as wide-ranging as driverless cars, precision munitions, and automated supply chain management.

State-of-the-art military sensors today rely on “active electronics” to detect vibration, light, sound or other signals. That means they constantly consume power, with much of that power and time spent processing what often turns out to be irrelevant data. This power consumption limits sensors’ useful lifetimes to a few weeks or months when operating from state-of-the-art batteries, and has slowed the development of new sensor technologies and capabilities. Moreover, the chronic need to redeploy power-depleted sensors is not only costly and time-consuming but also increases warfighter exposure to danger.

The Direct On-Chip Digital Optical Synthesizer (DODOS) program seeks to create a technological revolution in optical frequency control analogous to the disruptive advances in microwave frequency control in the 1940s.