Using a few-layer black phosphorus (BP) thin film that acts as a saturable absorber (SA) in an ytterbium-doped fiber laser setup, we experimentally demonstrated a passively dualwavelength Q-switching laser operation. The setup also incorporated a D-shaped polished fiber as a wavelength selective filter. As the SA was used in the ring cavity, a dual-wavelength Q-switch produced consistent outputs at 1038.68 and 1042.05 nm. A maximum pulse energy of 2.09 nJ with a shortest pulse width of 1.16 µs was measured for the achieved pulses. In addition, the repetition rate increased from 52.52 to 58.73 kHz with the increment of the pump level. Throughout the measurement process, the results were obtained consistently and this demonstrates that the BP film is a very good candidate to produce Q-switching pulses for the 1 micron region.

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In this paper, we have successfully demonstrated a stable dual, triple and quad-wavelength generation of ytterbium-doped fiber by incorporating a non-adiabatic microfiber interferometer (N-MI) into the laser ring cavity. Three sets of dual-wavelength, two sets of triple-wavelength and one set of quad-wavelength with the same wavelength spacing of 4.24 nm for all sets of multiwavelengths over the range of 1035 nm to 1050 nm are obtained by means of a nonlinear polarization rotation mechanism. The side-mode suppression ratio (SMSR) is ~53 dBm while the wavelength fluctuation and maximum power are 0.01 nm and less than 0.6 dB, respectively. Such features offer flexibility in multiwavelength generation and a stable output, with addition to a reliable system at an ambient temperature.

A thulium-doped fiber laser (TDFL) with a tunable Q-switched output is proposed and demonstrated. A silver nanoparticle based saturable absorber is used to generate the Q-switched pulses, while a tunable Mach-Zehnder filter acts as the wavelength-tuning mechanism. The TDFL has an operating wavelength range of 1916.5-1945.3 nm, with output pulses that have a repetition rate of 50.1 kHz and a pulse width of 5.1 µs, as well as a pulse energy of 69.3 nJ at the maximum pump power. The Q-switched pulses obtained are very stable and have a signal-to-noise ratio of 34.18 dB.

A simple ytterbium doped fiber laser (YDFL) setup was used to generate Q-switching pulses by using a D-shaped polished fiber as a wavelength selective filter. The gain medium used in the cavity was ytterbium doped fiber with length 70 cm. By utilizing a MoSe 2 film as saturable absorber into the cavity, a stable dual wavelength was produced at 1036.69 and 1039.22 nm. The wavelength separation of the output spectrum was 2.53 nm. We found a maximum pulse energy of 0.99 nJ and shortest pulse width of 1.2 µs. We have determined consistent dualwavelength Q-switching pulses for the 1-micron region.