Wavelength Tunable Fiber Lasers Based On Microfiber Couplers

Microfiber refers to a fiber that further reduces the diameter of the ordinary fiber to a micro/nano size.The microfiber has many applications.Microfiber coupler is one of the most important devices of microfiber.Microfiber coupler needs two optical fibers at least.The above optical fibers are drawn,and the microfiber coupler formed by the coupling of the evanescent field.They can be used for sensing,communication,fiber lasers and so on.Fiber lasers have raised the attention of the research and industry since their invention.Fiber lasers are divided into continuous laser and pulsed laser according to the output state.The way to obtain laser output is also varied.Fiber lasers use doping fibers to achieve different wavelength output.At the same time,different laser cavity structures can also be used for fiber lasers.Fiber lasers can be used in industrial processing,communications,sensing,medical and nonlinear research.With the improvement of industry,the requirements for pulsed laser are becoming higher and the same for tunable wavelength.1.2x2 microfiber coupler and 3×3 microfiber coupler were prepared by the flame-brushing method.The coupling mode theory is used to explain the principle of coupling of the microfiber coupler,and the optical fiber is drawn to a certain scale.A part of the field will be spread in the form of evanescent fields.The preparation process of the 3×3 microfiber coupler is relatively complex,and the preparation process of the 3x3 micro-fiber coupler will be described in detail.2.Based on a 3×3 microfiber coupler,a continuous fiber laser with Sagnac ring structure is fabricated.The theory and application of the fiber Sagnac ring are introduced.The constructed fiber laser has a stable continuous laser output.The birefringence effect of the microfiber coupler makes the microfiber coupler function as a filter in the laser cavity.Therefore,the microfiber can be adjusted by adjusting the waist area of the micro-fiber coupler using the external field strain.The output intensity variation of the coupler changes the continuous laser wavelength.3.Based on a 2×2 microfiber coupler connected to the laser ring cavity,the MoS2-fiber jumper integrated device is used as a saturable absorber in the laser cavity to generate a Q-switched fiber laser,and the relationship of the wavelength and strain of the microfiber coupler is theoretically studied.This paper explain the output wavelength variation of the Q-switched pulse by adjusting the microfiber coupler with the external strain.4.The mode-locked laser is obtained by using a SESAM and a CNT-fiber integrated device.The output of mode-locked laser wavelength can also be tuned by using the external strain adjustment of the 2×2 microfiber coupler.