We study the mode evolution properties in a 3 x 1 adiabatic tapered single-mode fiber combiner (ATSMFC) in theory. The fabrication of the combiner for single mode fibers based on adiabatic tapered fused bundle (TFB) technique with the assistant of low index glass capillary is introduced. The whole taper region can be seen as three phase: single-mode fibers, multi-core fiber and multi-mode fiber. Supermodes of three-core fiber with scalar mode results are derived based on coupling mode theory. The analysis is verified with numerical examples by fully vectorial finite element mode solver (Cosmol Multiphysics). Simulation results show that the three input core modes in single-mode fibers gradually evolve into three supermodes in three-core fiber and then evolve into three low-order modes in the multi-core fiber. Effective indices for different modes are calculated which can depict the evolution process vividly. The results may be useful for practical high power fiber laser systems.
Different methods for stripping cladding light in the high-power fiber laser have been presented. Original fluoroacrylate jacket of fiber selected 50mm-length is continuous removed, then use three different index polymers recoated the selected section to make the uniform light stripping possible. The power-handling capability of the device is
tested over 140W cladding light, attenuation of 15dB is achieved and the local temperature does not exceed 70°C.
Because of the diversified properties Fiber Laser affords a wide field of application. But restricted by nonlinear effects,
heat damage and other elements, it is impossible to increase the output power unlimitedly. When single fiber can't meet,
it needs to use Fiber Laser through beam combination to get high output power. Undoubtedly combiners play an
important role for increasing the output power of Fiber Laser. The advent of Photonic crystal fiber (PCF) abound the
kinds of combiners. It has numerous benefits and widespread application value. First, build the model of PCF combiners.
Then through Finite Difference Method(FDM), calculate the effect of PCF combiners on the whole loss under different
lengths of transition zone. Finally, compare the results. Through the results of numerical simulation calculation: when
the length of Transition zone L is shorter than the diffraction length of the tapered L0, loss will go down with the increase
of L; however, when L is far longer than L0, the increase of L will have negligible effect on the decrease of loss. So the
conclusion is significant to both increase the performance of Photonic crystal fiber combiner and decrease the loss.
Passive coherent beam combining, which uses optical feedback from the fibers to force all to lock in phase, seems to be a
promising way for high power output. Fused-taper fiber laser array is one of the passive methods, in which phase locking
is realized by mutual energy coupling, without any active phase control. In this paper, we use a dynamical model to
express phase-locking evolution of the fused-taper fiber laser array theoretically. In the numerical analysis of 3- and 7-
fused-taper fiber arrays, we start the simulations beginning with each laser in an off-state, that is, the initial electric fields
are chosen at random of order 0.1 and the phases are uniformly distributed. The results show that the array can achieve a
relative in-phase state. The coupling degree varies with the distance between the two neighbor fibers. The simulations
also show that the fiber grating reflectivity, the pumping parameters and the coupling length have significant effect on
the stability of the coherent combing.