MULTIFUNCTIONAL FIBEROPTIC MICROWAVE LINKS BASED ON REMOTE HETERODYNE-DETECTION

The multifunctionality of microwave links based on remote heterodyne d etection (RHD) of signals from a dual-frequency laser transmitter is d iscussed and experimentally demonstrated in this paper. Typically, dir ect detection (DD) in conjunction with optical intensity modulation is used to implement fiber-optic microwave links. The resulting links ar e inherently transparent. As opposed to DD links, RHD links can perfor m radio-system functionalities such as modulation and frequency conver sion in addition to transparency. All of these three functionalities a re presented and experimentally demonstrated with an RHD link based on a dual-frequency laser transmitter with two offset phase-locked semic onductor lasers, In the modulating link, a 1-Gb/s baseband signal is Q PSK modulated onto a 9-GHz RF carrier, The frequency converting link d emonstrates up-conversion of a 100-Mb/s PSK signal from a 2-GHz carrie r to a 9-GHz carrier with penalty-free transmission over 25 km of opti cal fiber. Finally, the transparent link transmits a standard FM video 7.6-GHz radio-link signal over 25 km of optical fiber without measura ble distortion.