We have demonstrated a passive Q-switched Thulium-doped fiber laser (TDFL using samarium oxide (Sm2O3) nanomaterial as saturable absorber (SA). The Sm2O3 based SA was fabricated by simply mixing the Sm2O3 powder solution with polyvinyl alcohol (PVA) solution. The homogeneously mixed solution was spread and dry to form a thin film. A piece of 1 mm x 1 mm of the SA thin film is sandwiched between two fiber ferrules and incorporated into a TDFL ring cavity for pulses generation. By controlling the loss and gain in the cavity, stable Q-switching operation was generated. The repetition rate was tunable from 17.62 kHz to 29.20 kHz by varying the pump power from 619 mW to 784 mW. The smallest pulse width of 3.54 mu s and the highest pulse energy of 0.20 uJ were obtained at the highest pump power.

We propose a segment of 11 cm long Thulium-doped fiber (TDF) as a passive saturable absorber (SA) in generating a stable Q-switched Erbium-doped fiber laser (EDFL). The obtained pulsed laser has a central wavelength of 1560 nm and emerges stably within a repetition rate range of 54.1-106.7 kHz over a pump power range of 35-136 mW. At the maximum pump power of 136 mW, the EDFL produces a maximum output power of 14.3 mW, a maximum pulse energy of 134.7 nJ and a maximum peak power of 41 mW as well as the narrowest pulse width of 3.28 µs. The fundamental frequency of the pulsed laser has a signal to noise ratio (SNR) of approximately 63 dB. The proposed laser would have a good prospect for material processing and medicine.

We demonstrate a Q-switched thulium-doped fibre laser operating at approximately 1935nm wavelength using anatase titanium(IV) oxide (TiO2) embedded in polyvinyl alcohol as the passive newly saturable absorber (SA). The film has absorption loss of 3.5dB and modulation depth of 33%. It is sandwiched between two fibre ferrules in a ring laser cavity to produce self-started pulse train with a repetition rate that is tuned from 30.12 to 36.96kHz as the 1552-nm pump power is increased from 289 to 485mW. At maximum pump power, the laser produced a Q-switching pulse train with pulse duration, output power, pulse energy and peak power of 1.91s, 11mW, 0.3J and 146mW, respectively. These results show that the TiO2 is a new potential SA material for pulsed laser applications.

We demonstrate a dual-wavelength Q-switched Ytterbium doped fiber laser (YDFL) using a newly developed multi-layer black phosphorous (BP) saturable absorber (SA). The BP SA is prepared by mechanically exfoliating BP crystal and fixing the acquired BP flakes onto the scotch tape. A small piece of the tape is then sandwiched between two ferrules and incorporated in cladding pumped YDFL cavity to achieve stable Q-switched operation at 1.0 mu m region. The laser has a pump threshold of 816 mW, a pulse repetition rate tunable from 10.9 to 23.87 kHz, and a narrow pulsewidth of 9.3 mu s. Our results show that multi-layer BP is a promising SA for Q-switching laser operation.

This paper reports a few-layer black phosphorus (BP) as a saturable absorber (SA) or phase-locker in generating mode-locked pulses from a double-clad ytterbium-doped fiber laser (YDFL). We mechanically exfoliated the BP flakes from BP crystal through a scotch tape, and repeatedly press until the flakes thin and spread homogenously. Then, a piece of BP tape was inserted in the cavity between two fiber connectors end facet. Under 810 mW to 1320 mW pump power, stable mode-locked operation at 1085 nm with a repetition rate of 13.4 MHz is successfully achieved in normal dispersion regime. Before mode-locked operation disappears above maximum pump, the output power and pulse energy is about 80 mW and 6 nJ, respectively. This mode-locked laser produces peak power of 0.74 kW. Our work may validates BP SA as a phase-locker related to two-dimensional nanomaterials and pulsed generation in normal dispersion regime.

We demonstrate the generation of Q-switched pulses from an ytterbium-doped fiber laser (YDFL) using quantum dot (QD) CdSe as a passive saturable absorber (SA). The CdSe QD is fabricated by the synthesis of CdO, Se, and manganese acetate and paraffin oil and oleic acid as the solvent and surfactant, respectively. The CdSe QD is then doped into poly-methyl-methacrylate (PMMA) via an emulsion polymerization process. A PMMA-hosted CdSe QD thin flake with a homogeneous end surface is then formed and placed between two ferrules and assembled in a YDFL cavity to achieve the Q-switching operation with a repetition rate of 24.45 to 40.50 kHz while varying the pump power from 975 to 1196 mW. The pulse width changes from 6.78 to 3.65 μs with a maximum calculated pulse energy at 0.77 μJ at a pump power of 1101 mW. This work may be the first demonstration of CdSe QD-based Q-switching in an all-fiber configuration that should give proportional insight into semiconductor QD materials in photonics applications.

We report an efficient method for generating a 2 micron laser based on an optical parametric oscillator (OPO). It uses a long piece of a newly developed double-clad ytterbium-doped fiber (YDF), which is obtained by doping multi-elements of ZrO2, CeO2 and CaO in a phosphoalumina-silica glass as a gain medium. The efficient 2 micron laser generation is successful due to the presence of partially crystalline Yb-doped ZrO2 nano-particles that serve as a nonlinear material in a linear cavity configuration and high watt-level pump power. Stable self-wavelength double lasing at 2122 nm with an efficiency of 7.15% is successfully recorded. At a maximum pump power of 4.1 W, the output power is about 201 mW.