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We describe an analog microwave photonic link system, which is used to transmit in a multiplexed way a TV signal over 30 km of standard optical fiber. The experimental setup is composed mainly by two distributed feedback (DFB) laser diodes emitting at 1500 nm. When these DFB lasers are operated in the low laser threshold current region, relaxation oscillation frequencies are obtained. Relaxation oscillations in the laser intensity can be seen as sidebands on both sides of the main laser line. The optical emissions generated in each laser are combined and amplified by using an erbium-doped fiber amplifier. Next, the amplified optical signal is detected by a fast photo-detector using direct detection method, and as result of this photo-detection, microwave signals are generated. Since microwave signals obtained by using this technique are tuned continuously; we can use them as electrical carriers to transmit simultaneously a TV signal at 4 and 5 GHz and over 30 km of standard optical fiber by using a Mach-Zehnder modulator. At the end of the optical link the modulated light is photo-detected in order to recover efficiently and successfully the analog TV signal. [ABSTRACT FROM AUTHOR]

This paper presents a novel system for sensing electric signals using an electrooptic modulator and optical coherence modulation. The system consists of an integrated optics coherence modulator acting as electric signal sensor in the frequency range up to 900 MHz. The main features of coherence-modulated transmissions include the need of using broad-band optical sources and lithium niobate electrooptic retarders. When low-coherence optical sources are used, the retarders introduce optical delays which are modulated by detected electric signals. The optical delays carry electric signals and are transmitted in the optical channel to a receiver. In this case, a scanning Michelson interferometer is used as an optical receiver, which measures the autocorrelation of light. The sensed electric signal is obtained when the interferometer is matched with optical delays on the detecting devices. Coherence-modulated systems have been studied for the last few years as new potential high-speed optical links useful for local area networks, point-to-point, and bidirectional transmissions. [ABSTRACT FROM AUTHOR]