Nanosecond pulse laser generation at 1.55 and 2 μm regions by integrating a piece of newly developed chromium-doped fiber-based saturable absorber.

Abstract

This paper demonstrated the nanosecond pulse laser operation at 1.55 and 2μm wavelength regions using a newly develop chromium-doped fiber (CrDF) as a saturable absorber (SA) to convert efficiently continuous-wave laser operation to nanosecond pulse laser operation. The laser uses an erbium-doped fiber (EDF) and thulium-doped fiber as the gain medium. A piece of 10cm long CrDF was integrated into both laser cavities to generate nanosecond pulse laser operation. In 1.55 region generation, an additional single-mode fiber (SMF) 100m long was added into the EDF laser cavity. Stable pulse generation occurred at a repetition rate of 1MHz with a pulse width of 432ns and a signal-to-noise ratio (SNR) of 66dB. The highest peak power of 24mW was obtained at 142mW pump power. In 2μm region generation, the obtained repetition rate was 10MHz with a pulse width and SNR of 59ns and 41dB, respectively. The highest peak power was only 8.3mW. By looking into the findings, the newly developed CrDF SA has a potential to be further enhanced toward better generation of ultrashort pulse fiber lasers.