Design Of Fiber Coupling Of Single Emitters Diode Laser

The high power diode laser has been widely used in the areas of material processing, laser pumping and national security. Diode laser stacks and bars have extremely high output power, but it is difficult to be coupled into small core fiber due to its poor beam quality limitations. High output power in small core fiber with good beam quality, long lifetime and convenient adjustment can be realized with the beam combination based on multiple emitter diode lasers. This thesis presents a research on fiber coupling of single emitter diode laser technology. Relevant design, simulation and the experimental results is discussed.A fiber coupled module based on multiple single emitters diode laser with the wavelength of 980 nm and output power of 12 W is designed. The divergence angle of 16 single emitters diode lasers in the direction of the fast axis is collimated with the aspherical lens, and the divergence angle in the direction of the slow axis is collimated with cylindrical lens. The beams are combined with isosceles right-angle prisms. The beam is expanded with a one-dimensional Galilean telescope at the slow axis, and coupled with efficiency of 88.9% into a fiber with the diameter of 100 μm and the numerical aperture of 0.22. The output power and total system efficiency are 137 W and 71%, which lays a good foundation for the fiber coupling of single emitters diode laser.The tolerance for fiber coupling system of single emitters diode laser is analyzed. The error of optical adjustment is simulated with the ray-tracing method. The impact of total system efficiency with the position errors and angle errors of optical devices such as FAC and SAC, isosceles right-angle prisms, beam expanding system are discussed. The total system efficiency is mainly affected by the position error of FAC in the direction of fast axis, and the tolerance is from-470 nm to 500 nm.The coupling experiment of single emitters diode laser was demonstrated. To illustrate the coupling effect, three single emitters diode laser located at the center and both ends are chosen. The result shows that the total system efficiency reaches 67.1%, which is consistent with simulation and may be used in high power diode laser applications.