Layered structured binary alkaline metal phosphide of KP₁₅ as saturable absorbers for ultrashort pulsed laser generation

Abstract

We demonstrated an all-fiber passively mode-locked 980 nm picosecond laser using KP 15 materials as saturable absorbers (SAs). The micron-sized wire-like KP 15 crystals were prepared using a vapor-phase transfer method. The material not only shows excellent optoelectronic properties, such as optical anisotropic and large binding energy, but also longterm stability. By inserting the KP 15 crystals into the ytterbium-doped all-fiber laser cavity, a mode-locked 980 nm laser with a pulse duration of 30 ps, a repetition rate of 15.65 MHz and spectral width of 5.6 nm was achieved for the first time, to the best of our knowledge. In addition, we investigated the long-term stability of the KP 15 -based mode-locked 980 nm laser, and the root-mean-square of the output power of the picosecond pulse was only 1.03% when operating for 4 h. The results indicated that the KP 15 material prepared using a chemical vapor transport method was a promising SA for ultrafast fiber laser generation.