U. Gliese et al., MULTIFUNCTIONAL FIBEROPTIC MICROWAVE LINKS BASED ON REMOTE HETERODYNE-DETECTION, IEEE transactions on microwave theory and techniques, 46(5), 1998, pp. 458-468
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.