Research On Outputting Technology Of High Power Diode Laser Coupling With Optical Fiber

Fiber coupled high-power laser diode has obvious advantages like the small size, excellent output beam quality, long life time, and good stability. This module can be applied in pumping high-power fiber laser, processing materials and medical treatments. The background of this paper is to promote the directly application of fiber coupled high-power laser diode in laser manufacturing, and its investigated subjects are improving the output performance of fiber coupled high-power diode laser. In this thesis, the research are studied by theoretical and experimental analyse, including:1. The basic theories are offered which include the optical transmission theory in fiber and laser diode with fiber coupled. The coupling methods are compared and classified.2. In the paper, the fiber array as fiber beam reshaper is used. Diode laser array phase-locked in an external cavity can be achieved. We named this method as Fiber coupled diode laser phase-locked in the external cavity. Using this method, the spectrum width is narrowed in experiment.The output beam quality of laser diode array has been improved.3. The properties of high power diode laser transmit in the tapered fiber are investigated in many aspect, including:Base on light ray theory the power transmission efficiency of tapered fibers depends on the minimal diameter of taper waist is analyzed. The light energy transfer efficiency can be calculated by a method named as effective numerical aperture.When double-clad fiber as a receiver is used, the effective transmission proportion of high-power diode laser in tapered optical fiber is calculated.A fused tapered system is designed.In the experiment, according to the theory achieve the double taper transition with fusion-elongation. The power transmission efficiency of high-power diode laser relevant to minimal diameter and tapered length of taper waist is observed.Combined with the characteristics of tapered fiber, the property of energy transfer in cladding are investigated in experiment. In the experiment, the tapered waist is immersed in a glue with high refractive index.And the transmission property of cladding can be tested when the high-power diode laser transfer in tapered optical fiber. The study results provide important theoretical and experimental guidance of design and application of high power fiber combiners.4. Based on the analysis of propagation ray theory in the bending optical fiber, a new approach to judge the beam quality of fiber coupled laser diode by bending fiber is presented. Output power differences are given by fiber coupled laser diodes with the same nominal output power and pigtail fiber in bending fiber experiments. It also can be used in detecting of fiber coupled efficiency of laser diode.This research is used for improving the efficiency of fiber laser pumping and stability.And it provides a new way of thinking and theoretical and experimental basis of coupling effect measurement of fiber-coupled diode laser.