Advances in the optical heterodyne reception

The prospects for the use of optical heterodyne reception in signal transmission, distribution, and other possible applications will be asserted and their features will be discussed. Application of optical heterodyning in photonic systems, such as analog signal transmission, high-speed electronics and optoelectronics instrumentation for measurement, signal processing, etc. is believed the inherent area in near future. Recent rapid progress in photonic technologies urges us to evolve promising new applications and to evaluate their feasibility, although only a limited number of examples have been reported. Utilization of heterodyne detection in Digital Transmission Systems is one of the most promising and leading topics. And the other direct application is microwave signal transmission with a Fiber Optic Link. To deliver microwave or millimeter-wave signals from one place to distant places, the rf signal is transformed to the optical signal by modulating lightwave, then making use of the lowloss property of the optical fiber it is delivered to its destination, where the lightwave is demodulated, and amplifled by the electronic circuit (e.g. MMIC) if necessary, to yield the original electrical signal. Endeavors to realize stable, low-noise Signal Generation is also pursued adopting optical heterodyne systems. Measurement is another field of interest. Precise measurement of distance, or a range finder, for instance, is a promising application of the optical heterodyne reception. The other interesting topic is the direct mixing of microwave/millimeter wave with light wave by using three terminal electronics devices, such as, FET, HEMT, and HBT.