| Nowadays cable is the main way of electrical power transmission. However, it has large influence on the transmitting electrical powerduring this process because of the electromagnetic interference and the cable resistance,which leads to the limited application of the cable in some high-magnetic fields. As the development of optical fiber and its application, the electrical power transmission system based on optical fiber, namely power-over-fiber system, is proposed due to the optical fiber characteristics of low attention, light weight, anti-electronmagetic interference and lightning protection. However because of the limition of stimulated Brillouin scattering effect, the power transported in optical fibers can not unlimitedly increase. Stimulated Brillouin scattering effect of optical fibers is a nonliner effect generated by injecting high power light into an optical fiber, and it will cause the most optical power backscattering to the injected point of the optical fiber, which leads to the limition of output optical power at the end of the optial fiber. Besides, stimulated Brillouin scattering threshold of a long-distance optical fiber is so low, usually a dozen milliwatts. Thus stimulated Brillouin scattering effect limits the performance of long-distance single-mode fiber transmission system and the driving capability of power-over-fiber system which transports electrical power through optical fibers.In this paper, a distributed feedback semiconductor laser diode which is directly modulated by a noise signal can broaden the laser linewidth, suppress the stimulated Brillouin scattering effect of optical fibers, increase the transmission optical power at the end of optical fibers and improve theperformanceof power-over-fiber system. In addition, the noise-modulated distributed feedback semiconductor laser diode has little impact on the laser’s time series, power spectrum and optical spectrum. The method proposed by us is simple and practical and can tune the linewidth of the laser flexibly. It can be realized by adding a noise signal generator to original long-distance single-mode fiber transmission system and then the output optical power can be increased significantly and the performance of power-over-fiber system can also be improved.In order to inhibit the stimulated Brillouin scattering effect of optical fibers and improve the performance of power-over-fiber system, we have finished these worksas following:1) The influence factors of stimulated Brillouin scattering is theoretically and numerically simulated by matlab. The result shows that the stimulated Brillouin scattering threshold decreases drastically and the remains unchanged with the increase of optical fiber length. The most important result is that the stimulated Brillouin scattering threshold is theoretically proporational to the linewidth of the pump light.2) The change of time series, power spectrum and optical spectrum of nosie-modulated distributed feedback semiconductor laser diode is analyzed, and we have also precisely measured the linewidth of laser diode through Delayed Self-heterodyne interferometer. The experimental results show that the noise-modulated distributed feedback semiconductor laser diode has little influence on the laser’s time series, power spectrum and optical spectrum, and at the same time the linewidth of laser can be broadened from 2.43 MHz to 379.89 MHz continuously.3) The experimental systemmeasuringthe stimulated Brillouin scattering threshold of optical fibers is set up. The effects of laser linewidth, optical fiber length on stimulated Brillouin scattering threshold are analyzed. In addition, the impact of laser linewidth on saturated output electrical power in power-over-fiber system isalso experimentally measured. The results show that with the laser linewidth increasing from 2.43 MHz to 379.89 MHz, the amplitude of the backscattering Brillouin stokes light is inhibited by 40.90 dB. Meanwhile, the stimulated Brillouin scattering threshold and the saturated output electrical power averagely raise 7.19 dB and 13.55 dB, respectively. Thus the noise-modulated distributed feedback semiconductor laser diode can be used to suppress thestimulated Brillouin scattering effectively,increase the stimulated Brillouin scattering threshold and improve the performance of power-over-fiber system. |
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