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As Mobile data traffic increasingly grows, radio-over-fiber (RoF) becomes an indispensable technology by extending the coverage for many wireless applications such as mobile local area networks [1]. RoF links need both local and remote ends to transmit/receive RF signals while the power supply of the remote end may be a problem due to unpowered locations or far from power sources [1]. Power-over-fiber (PoF) is an attractive technique for RoF system to simplify its power supply for remote ends by delivering power via optical fibers [2]. Moreover, PoF technology has advantages such as being free from electromagnetic interference, high voltage isolation, convenient system integration, etc. [3]. Several studies have explored PoF systems. Matsuura [2] demonstrated bidirectional radio-over-fiber transmission over a 300m double-clad fiber with 60W optical feed power. Yu [4] delivered 93mW of optical power via a 103km single-mode fiber and 23mW electric power is obtained through photoelectric conversion. Wake [5] achieved to deliver optical power of 250mW over a link length of 300m. However, the transmission distance or the delivered optical power, which are key requirements for the ROF system, was largely limited in the previous work due to the properties of the optical fibers or the working transmission wavelength. In this work, a signal and power over fiber (S-PoF) system is demonstrated using a few-mode/single-mode fiber hybrid system to deliver high optical feed power and maintain the ability to transmit optical signals. 643mW optical power is successfully delivered after a 28km few-mode/single-mode fiber channel, which is improved by 43% compared to the single-mode power-over-fiber system at the same testing condition. The largely improved optical power handling capacity is benefits from the much larger mode field area of few-mode fiber (around 2.5-3.75 times of SMF28e fiber), which improves the critical power of simulated nonlinear scattering.
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