Researchers from the University of Glasgow (Scotland), A. F. Ioffe PhysicoTechnical Institute (St. Petersburg, Russia), and the University of Kassel (Germany) have used a modelocked semiconductor laser as a mixer to u¥and downconvert applied microwave signals to optical signals. By combining a twosection laser (gain region and saturable absorber modulator) and optical power amplifier, a highfrequency signal can be transmitted, resulting in a socalled fiberradio. Fiberradio technology is currently being developed by a number of telecommunications companies. According to the researchers, the key to accessing ultrahigh frequencies is to generate a localoscillator (LO) signal and to use it in a mixer. To date, optoelectronic mixers have only provided output as an electrical signal; these experiments demonstrate that mixing can be performed optically.
Temperature and wavelength changes tailor terahert¥emission from InSb