Random fiber laser of semiconductor laser cascaded pump

Abstract

The invention provides a random fiber laser system and belongs to the novel laser device field. In the system, a traditional single-mode fiber is taken as a laser medium, and a cascaded semiconductor laser is taken as pump light which is coupled to the fiber along an opposite direction from a middle point of the fiber. Photon is in propagation in the fiber, scattering is generated because of nonuniform random refractive index, and distributed Rayleigh scattering is formed. The pump light provides distributed Raman gain along the fiber. When total gain is greater than total loss, backward scattered photon is amplified to generate laser. Frequency of random laser is a result of frequency of last grade pump light shifting downward with 13 THz. By properly selecting pump light, output of the random laser in a whole fiber transparent window is realized. By using cascaded semiconductor laser as the pump light, not only is Raman gain spectrum bandwidth increased, but also Raman gain form is controlled. Thereby the random laser in the invention has the characteristics of controllable mode, super-long transmission, low threshold, high output power and the like.

Description

technical field [0001] The invention relates to a system in which distributed Rayleigh scattering in an optical fiber is amplified by Raman to form laser light. Compared with traditional fiber lasers, this system has no cavity mirror. It belongs to the field of new laser devices. Background technique [0002] In the literature Sergei K. Turitsyn, Sergey A. Babin, Atalla E. E1-Taher, Paul Harper, Dmitriy V. Churkin, Sergey I. Kablukov, Juan Diego Ania-Castanon, Vassilis Karalekas and Evgenii V. Podivilov. Random distributed feedback fiber laser A random fiber laser system is introduced in .Nature Photon.2010, 4, 231-235. In this system, two beams of equal-power 1455nm pump light are coupled into the fiber from the midpoint of the fiber in opposite directions (the total length of the fiber is 83 km). The photons transmitted in the fiber are coherently scattered due to the inhomogeneous refractive index, forming distributed Rayleigh scattering (RS), and most of the scattered...

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Problems solved by technology

In the above system, the threshold value of the laser is relatively high, reaching 1.6W. Such a high threshold value requires too high power of the pump light, and it is difficult to realize, so we must try our best to reduce the threshold value.

[0005] 2. The output power of the laser needs to be further improved

Although the output power has reached 150mW, it still cannot meet the higher power requirements in many applications. Increasing the power can also increase the transmission distance of light and increase the length of the laser to meet the needs of long-distance transmission in communication applications.

[0006] 3. Higher cost

The Raman fiber laser used in the experiment is relatively expensive

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