Research On Random Fiber Laser Based On Communication Fiber

Random fiber laser(RFL) has attracted many research interests since it was proposed because of the abundant physical mechanism. In additional, with the development of the laser pumping technology and optical fiber technology, fiber laser has become more important in the field of solid lasers and owned huge prospects of fiber sensing, fiber communication and industry machining. In 2010, Prof. Turitsyn from Aston University proposed random distributed feedback fiber laser based on standard communication fiber for the first time. Since then, RFL has become a new branch of random laser and fiber laser and attracted interests of researchers.In fact, RFL does not have a long history and many theories of RFL are not completed. This paper specially focused on the study on the RFL with low-threshold and high-efficiency linearly output. This paper also comprehensively investigated the configurations and performances of this kind of RFL, theoretically and experimentally. It constructed the complete theory from 1st order to high order linearly output RFL. Referring to the design of this kind of laser, this paper proposed a novel high precision, long distance cross-correlation OTDR.In detail, this paper developed the methods to construct 1st order low-threshold, high-efficiency linearly output RFL which was based on stable balanced power model and revealed the mechanism to obtain high-efficiency random laser with this configuration. According to the theoretical analysis, the position of point feedback, the pumping wavelength and the fiber cavity length are the key factors to achieve this sort of RFL. Considering the key factors, this paper built an experiment setup with 5km fiber and 1090 nm pump source. Finally, we achieved a linearly output RFL operating at 1145 nm and it accompanied with low-threshold(2W), high-efficiency(>90% slope efficiency) and high power(7.13 W output with 10 W pump) properties.Furthermore, this paper developed high order linearly output RFL based on the results with 1st order output. To achieve high order output, we referred to the existed achievements about RFL’s sensitivity range to the reflectivity of point feedback and proposed a method(replacing the traditional point reflected mirror by the Fresnel reflection) which satisfied the effective feedback and avoided the cross talk between all the Stokes waves, resulting in high order linearly output RFL successfully. Meanwhile, we investigated the power distribution, optical conversion efficiency and other characteristics of this RFL and provided theoretical guide to design such a RFL. Especially, we provided the necessary guidance on how to designing a such RFL with maximum conversion efficiency and specific output power. The experimentally demonstrated 2nd order RFL achieved slope efficiency at 48.8% and maximum output power ~2W(limited by the maximum pump power 8.75W). The most importantly, the linearly output property is preferable in many different applications.Finally, this paper demonstrated an all fiber ultra-broad chaotic light source referring to the constructing method to a RFL and realized a high-precision, long-distance cross-correlation OTDR based on the chaotic source. Besides, we detailedly analyzed the key limiting factors to improving the performances of cross-correlation OTDR. We found that the way to solving this problem was improving the optical signal-to-noise ratio and we proposed two available methods: distributed Raman amplification and increasing the sampling time. At last, we successfully realized a cross-correlation OTDR monitoring fiber fault location with centimeter spatial resolution and over 100 km operation range.The achievements about linearly output RFL in this paper have important significances of enriching the theory of RFL. The exploration of the RFL’s application is helpful to the further engineering application of RFL.