Study On Optical Fiber Laser Based On Microstructure Fiber Filled With Graphene

With the development of optical fiber laser technology,some new progresses has been made about the study of passively mode-locked fiber laser.It can not only directly produce ultra-short pulse,but the quality of the pulse is superior to the traditional laser.In addition,it also has the advantages of small size and light weight.Therefore,passively mode-locker fiber laser become a hotspot in researching ultrashort pulse laser light source.The mode locker in passively mode-locked fiber laser is usually fabricated by single-mode fiber.But the area of the single mode transmission is small due to the small fiber core diameter.When the input optical power is high,some problems will appear such as nonlinear effect and heat loss in single-mode fiber.So it is difficult to achieve high-performance fiber laser.Compared to the tranditional single-mode fiber,microstructure fiber has many advantages,for example,controllable dispersion,high nonlinear effects and endless single-mode transmission and so on.Therefore,people pay more attention to microstructure fiber in researching passively mode-locker fiber laser.Graphene has many excellent optical properties due to its special atomic structure,including linear band structure,wide operating wavelength range and small coupling loss.Due to this kind of band structure,compared to other carbron materials,graphene has some advantages such as fast recovery time,high damage threshold,low saturation intensity and the operational ability in transmission,reflection and two-way modes.So it has been widely studied in the field of passively mode-locked fiber laser.The organic combination of graphene and microstructure fiber can make full use of their excellent optical characteristics.And we integrate it into the laser cavity for realizing passively mode-locked.The contents of this paper are as follows:1.The transmission properties of LMA-10 fiber is simulated.Some low-order modes will be excited in LMA-10 fiber when the input wavelength is 1550 nm,for example,linear polarization mode LP₀₁,TE₀₁,TE₀₂,TE₀₃ and TE₀₄ of TE mode and TM₀₁,TM₀₂,TM₀₃ and TM₀₄ of TM mode.The excitation modes of a particular wavelength will be determined when the fiber structure of microstructure fiber has been determined.2.We fill graphene dispersion into the air holes of LMA-8 and LMA-10 fiber cladding by using the method of vacuum and test the transmission properties of the filled LMA-10 fiber.The transmission spectrum changes with the change of the applied temperature.Therefore the whole process of laser experiment will be conducted at constant temperature.3.We integrate the filled LMA-8 fiber and LMA-10 fiber into the ring cavity structure,respectively.The center wavelength of the output pulse is 1562 nm when the filled LMA-8fiber is used as mode locker of passively mode-locked fiber laser.By adjusting the polarization controller we can achieve the input of pulse train with the repetition rate of 154 MHz,232 MHz,499 MHz and 698 MHz,respectively.The average output power is 1.4 mW.The center wavelength of the output pulse is 1566.5 nm when the filled LMA-10 fiber is used as mode locker of passively mode-locked fiber laser.By adjusting the polarization controller we can achieve the input of pulse train with the repetition rate of 6.95 MHz and 7.12 MHz,respectively.The average output power is 1 mW.