Properties of Non-Bridging Oxygen Hole Centers Defects in ${\rm Yb}^{3+}/{\rm Al}^{3+}$ Co-Doped Photonic Crystal Fiber by Using Powder Melting Technology

The Yb³⁺/Al³⁺ co-doped silica glass is prepared using the powder melting technology based on the high-frequency plasma furnace. The typical absorption and emission pattern of Yb³⁺ ions in the Yb³⁺/Al³⁺ co-doped silica glass and photonic crystal fiber (PCF) fabricated in our laboratory are demonstrated. The additional absorption peak at 260 nm and the 200 nm-excited emission peak at 630 nm indicate that the non-bridging oxygen hole centers (NBOHC) defects exist in the silica glass. Moreover, the luminescence peak at 735 nm is also related to the NBOHC defects. Spectral evolution of the NBOHC defects luminescence in relation to the excitation wavelength, excitation power, and PCF length are also analyzed. The laser slop efficiency of the PCF is 12.2%.