Courtesy of Michelle Campbell, Technical Communication Office
Naval Air Warfare Center - Weapons Division
National Society of Black Physicists President Dr. Peter Delfyett was the Distinguished Colloquium Speaker at the Naval Air Warfare Center - Weapons Division at China Lake on Aug. 12 and explained recent advancements in optical signal processing.
Today’s warfighter relies on current developments in high-speed optical communication and signal processing fields. Recently, traditional optical communication methods have undergone a transformation as a result of optical frequency and wavelength division multiplexing (WDM), in which multiple optical carrier signals can be combined into one signal on one optical fiber through the use of infrared (IR) wavelengths.
However, designing optical systems using hundreds of wavelengths is challenging. Delfyett, a University Trustee Chair Professor of Optics, Electrical and Computer Engineering, and Physics at the University of Central Florida, has been developing a compact, efficient optical source that can produce many optical frequencies and wavelength channels from a single device. With great enthusiasm, Delfyett explained the benefits of a mode-locked semiconductor laser that can generate coherent, phase stabilized optical frequency combs.
Selecting a source laser is an important component of developing an effective communication system. According to Delfyett, the advantages of using semiconductor lasers instead of solid-state lasers are numerous. “A conventional, solid-state laser is large and electrically inefficient,” he explained. “It operates at a relatively low speed of 100 megahertz (MHz). A semiconductor provides the right wavelength for the Depart of Defense (DoD), [from] 300 nanometers (nm) to greater than 10 microns (µm), via bandgap engineering. [A semiconductor laser] can be powered by watch batteries and is small (hundreds of microns) and lightweight.” Semiconductor lasers are also electrically efficient.
Delfyett also shared the benefits of using harmonic mode-locked lasers, which contain equidistant multiple pulses circulating within the resonator, rather than fundamental mode-locked lasers, which contain a single pulse circulating within the resonator. One benefit is that harmonic mode-locked lasers produce higher pulse repetition rates. However, harmonic mode-locked lasers can contain instabilities such as supermode noise. Delfyett and his team counter this with supermode suppression.
Audience member Philip Land, a member of NSBP, believes Delfyett’s research will greatly benefit the DoD, particularly those serving in the field. Fs mode-locked semiconductor laser-based optical frequency combs increase the speed of communication and simplify the operation and management of high capacity optical interconnects and links.
“Linkups, [such as] Link 16, are not as efficient,” said Land. “New technologies make communication more efficient, which decreases the time lag. New technologies could make communication instantaneous.”
The Colloquium Series offers NAWCWD personnel an opportunity to stay abreast of trends in defense‑applicable fields as well as to collaborate with top level researchers.
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