Time difference pumping stimulated Brillouin scattering device for optical fiber transmission seed laser and method

Abstract

The invention relates to a system for generating stimulated Brillouin scattering and a method. A seed laser (1) gives out seed laser, the seed laser is transmitted to an optical fiber beam splitter 2 through a polarization maintaining optical fiber and is then divided into two beams, the two beams of laser respectively enter a first polarization maintaining optical fiber 10 and a second polarization maintaining optical fiber 11 which are connected with the optical fiber beam splitter 2, the two polarization maintaining optical fibers are used for transmitting the respective laser beams into an optical fiber beam combiner 3 in a polarization maintaining mode, and an optical fiber time difference regulating device 5 is used for regulating the laser beams in the first polarization maintaining optical fiber 10 and the second polarization maintaining optical fiber 11 to reach the time difference of the optical fiber beam combiner 3, wherein the pumping time difference of two light pumping systems of laser amplification media is equal to the time difference for the laser beams of the first polarization maintaining optical fiber 10 and the second polarization maintaining optical fiber 11to reach the optical fiber beam combiner 3.

Description

technical field [0001] The invention relates to a Brillouin scattering laser device, which belongs to the technical field of photoelectron detection. Background technique [0002] At present, the technology of underwater target detection using Brillouin scattering has been practically applied. One of the biggest challenges in the development of this technology is the problem of detection distance. As we all know, the visible light window of fresh water or sea water is around 532nm, but even with this The wavelength of the laser is used as the laser wavelength for Brillouin scattering underwater detection. Due to the different water quality of the sea or lakes to be detected in practice, especially with the intensification of environmental pollution in recent years, there are generally poor water quality in various waters and poor water quality. The direct impact of laser underwater detection is that it seriously affects the transmission distance of the laser. Even in unpollu...

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Problems solved by technology

attached figure 1 And attached figure 2 All shown are cases of crossover setups with figure 1 In the process, two mirrors 102 and 103 are used to split a beam of laser light 101 into two beams, and then the separated two beams of laser light intersect in a stimulated Brillouin scattering medium 104 to generate stimulated Brillouin scattering light In this device, since one laser beam is divided into two beams, the frequency and polarization state of the two laser beams are exactly the same. The structure of the device is simple, but there are two problems. One problem is Since one laser beam is divided into two beams, the energy of the two laser beams must not be very high. The second problem is that the interaction distance between the two beams is very short due to the intersection method. , resulting in insufficient utilization of the laser beam

attached figure 2 It shows another way of intersecting setting. In order to improve the problem of dividing one laser beam into two beams and causing each energy to become smaller, it is proposed to use the beams emitted by two lasers 201 for intersecting incidence by means of a mirror 202 To the stimulated Brillouin scattering medium 203, each of them is an independent laser, so the energy will not become smaller. In order to ensure that the laser light emitted by the two lasers is exactly the same in nature to ensure the occurrence of stimulated amplification, The same seed laser needs to be injected into the two lasers respectively. In this way, although the system solves the problem of reducing the energy of the laser beam, the device still cannot solve the problem of short interaction distance

In order to solve the problem of short interaction distance, the best way is to overlap the optical paths of the two laser beams. In the existing optical path overlapping settings, as disclosed in the published Chinese patent application CN101266342A, in order to realize the two The pulsed laser beams are overlapped on one optical path with a time difference (which is required for secondary stimulated Brillouin amplification). The device uses photoelectric crystals to control the two laser beams with different polarization states, so as to ensure both The two pulsed lasers are coupled to one optical path with a time difference, and the same polarization state can be guaranteed when reaching the stimulated Brillouin scattering medium. In this device, a polarization coupling mirror and an electro-optic crystal are required to realize the front and rear two beams. The polarization state control of laser beams is not only complicated in structure, but also requires high requirements for electro-optic crystals, and is accompanied by the following problems. The two laser beams used in this device either divide one laser beam into two beams, so that It will lead to the reduction of the energy of the two laser beams. If the two laser beams generated by two lasers are used, although the energy intensity is kept from being reduced, the use of two lasers will take up more space correspondingly, because Two lasers obviously need to occupy twice as much space, and the space problem cannot be solved or it is very difficult to solve in many cases, or it will cause a rapid increase in cost

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