Thermo-optical analysis of air-clad photonic crystal fiber lasers

Progress of photonic crystal fibers and their applications

“…The higher the inner-cladding NA, the larger the acceptance angles, which can raise the coupling efficiency of pump laser diodes and decrease the cost of producing fiber lasers. Figure 1 shows the cut scanning electron microscope (SEM) images for the two kinds of double-cladding ytterbium-doped PCFs [17,20]. The core of PCF A, doped with 0.6 wt% ytterbium ions, has 0.05 core NA and is 28 µm in diameter.…”