Researchers Create New Class Of Photonic Waveguides With Low Signal Loss
4 December 2013
US researchers have successfully created a new class of photonic waveguides with a signal loss approaching that of optical fiber, a major breakthrough that could turn out to be key to curtailing the size and fostering the performance of photonic delay chips used in navigation sensors, radar systems and other military applications.
Optical fiber is known to have significantly low signal loss, making it the backbone of the global Internet, but connecting it with microchip-scale photonic systems is not the most viable option since optical fiber is limited in certain photonic delay applications and assembly requires a great number of connections, which leads to signal loss.
The method developed by two research teams, funded by the Defense Advance Research Project Agency's integrated Photonic Delay (iPhoD) program, involved the integration of low-signal long coils of waveguides onto microchips and up to 50 meters of coiled material to delay light. The waveguides also employ advanced silicon processing, providing for sub-micron precision and more efficient production. The experiment resulted in the creation of a smaller, more precise component.
The chip, with loss of about 0.05 decibels per meter, allowed the demonstration of a 50-meter optical delay on a single microchip, DARPA program manager Josh Conway said.
The method was subsequently applied by scientists from the University of California, Santa Barbara (UCSB) and the California Institute of Technology (CalTech). At UCSB the researchers were successful in the creation of an ultralow loss, true time delay chip from silicon nitride. The use of this material could support the chip's application in a number of devices and materials, providing for a reduction in size, weight and power requirements of an entire system.