Study On The Property Of Yb³⁺ Doped Double Clad Photonic Crystal Fiber Laser And Its Laser Performance

Double clad photonic crystal fibers (DC-PCF)can keep single mode behaviour as its effective mode area increasing, which results from the endlessly single mode property of PCF. It can effectively reduce the nonlinear effect without affecting the optical property. Therefore, DC-PCF is especially suitable for the transmission of high power laser. In this paper, we have investigate several optical properties of DC-PCF, such as the effective area, chromatic dispersion, confinement loss and so on. At the same time, the properties of Yb doped Double-Clad Photonic Crystal Fiber laser(Yb-DC-PCFL) was studied both in theory and experiment.The concrete content of this paper can be summarized by the following paragraph.1.We have introduced the basic structure, light guiding theory, and applications in fiber laser of Yb-DC-PCF. Based on the finite element method, we have studied the mode effective area, mode field diameter, numerical aperture, nonlinear coefficient and dispersion characteristics of Yb-DC-PCF. It can provide certain references for full understanding of Yb-DC-PCF optical properties, and is useful for further developing the application of Yb-DC-PCF.2. Based on laser steady rate equation, the power transmission characteristics of Yb-DC-PCFL was researched. The effects of reflectivity of mirror, power fill factor, fiber length and pump power on laser output power and threshold pump power were discussed. The results provide theoretical guidance for improving the slope efficiency and reduce the threshold pump power of fiber laser. We also analyzed how the fiber length and ion doping concentration influence the output wavelength properties of Yb-DC-PCFL. Which provides theory guidance for enriching the laser wavelength of Yb-DC-PCFL and restraining the mode competition effect.3. The experimental study of Yb-DC-PCFL has been made. The wavelength of fiber laser is1031.73nm, the spectral line width is about2.55nm. The mode competition phenomenon and amplified spontaneous emission effect was analyzed.