Zhipeng Qin

Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber laser at 2.8 μm

Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multilayer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 μm. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 μJ/cm(2), respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 μJ and pulse width of 1.18 μs at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-μm fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.

Generation of 103 fs mode-locked pulses by a gain linewidth-variable Nd,Y:CaF 2 disordered crystal

We have demonstrated a diode-pumped passively mode-locked femtosecond Nd,Y:CaF2 disordered crystal laser for the first time to our knowledge. By choosing appropriate Y-doping concentration, a broad fluorescence linewidth of 31 nm has been obtained from the gain linewidth-variable Nd,Y:CaF2 crystal. With the Nd,Y:CaF2 disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration as short as 103 fs, average output power of 89 mW, and repetition rate of 100 MHz. To our best knowledge, this is the shortest pulse generated from Nd-doped crystal lasers so far. The research results show that the Nd,Y:CaF2 disordered crystal will be a potential alternative as gain medium of repetitive chirped pulse amplification for high-peak-power lasers.

Black phosphorus as broadband saturable absorber for pulsed lasers from 1 μm to 2.7 μm wavelength

Universal saturable absorbers covering wavelengths from near-infrared to mid-infrared bands have attracted widespread interest. In this contribution, we experimentally demonstrated the broadband saturable absorption of multilayer black phosphorus from 1 μm to 2.7 μm wavelengths. With liquid-phase-exfoliated black phosphorus nanoflakes as the saturable absorber, the Q-switching operation of bulk lasers at 1.03 μm, 1.93 μm, and 2.72 μm was realized, respectively. This work will open up promising optoelectronic applications of black phosphorus for the mid-infrared spectral region.

Dual-wavelength synchronous operation of a mode-locked 2-μm Tm:CaYAlO 4 laser

We experimentally demonstrated dual-wavelength synchronous operation of a high-power passively mode-locked 2-μm Tm:CaYAlO4 (Tm:CYA) disordered crystal laser with semiconductor saturable absorber mirror (SESAM) as mode locker. The mode-locked laser emitted an average output power as high as 830 mW with pulse duration of 35.3 ps and repetition rate of 145.4 MHz. The mode-locking dual wavelengths were centered at 1958.9 nm and 1960.6 nm, respectively. Autocorrelation trace clearly shows beating pulses with pulse width of 3.5 ps and repetition rate of 0.13 THz.

Spectroscopic characteristics and laser performance of Tm:CaYAlO4 crystal

The spectroscopic characteristics of Tm:CaYAlO4 crystal were studied. Continuous wave laser operation at 2 μm was achieved with a 6 at.% Tm:CaYAlO4 (Tm:CYA) crystal pumped by a fiber-coupled laser diode. The laser emits a maximum output power of 4.3 W with a slope efficiency as high as 46.7%. In addition, a wavelength tuning experiment on Tm:CYA crystal was performed showing the Tm:CYA laser could be continuously tuned from 1861 to 2046 nm using an intracavity CaF2 prism, suggesting the potential of this crystal for ultrashort pulse generation by mode-locking.

Watt-level passively mode-locked Er 3+ -doped ZBLAN fiber laser at 2.8 μm

We experimentally demonstrated a stable, high-average-power, continuous-wave (CW) passively mode-locked Er(3+)-doped ZBLAN fiber laser at 2.8 μm based on a semiconductor saturable absorber mirror. A stable mode-locked laser with a signal-to-noise ratio of 52 dB and a slope efficiency of 14% was obtained. The highest average output power in excess of 1 W was generated at the incident pump power of 8.2 W, with a pulse repetition rate of 22.56 MHz and pulse duration of 25 ps. To the best of our knowledge, this is the highest average output power of a CW mode-locked ZBLAN fiber laser in the mid-infrared wavelength regime up to now.

Black phosphorus-based saturable absorber for Q-switched Tm:YAG ceramic laser

Abstract. We have experimentally demonstrated a passively Q-switched Tm-doped YAG ceramic laser with black phosphorus (BP) as saturable absorber (SA). According to the measurement, the BP saturable absorber mirror has a modulation depth of 5% and a saturation fluence of 20  μJ/cm2. The generated Q-switched pulse has a maximum average power of 38.5 mW and pulse energy of 3.32  μJ, with the corresponding repetition rate of 11.6 KHz and pulse width of 3.12  μs at 2  μm wavelength. The results show that BP is a promising SA for midinfrared-pulsed lasers.

SESAM mode-locked Tm:CALGO laser at 2 µm

GaSb-based SESAM is successfully employed for passive mode locking of a Tm3+:CaGdAlO4 laser operating near 2 µm. The pulse duration is around 650 fs at a repetition rate ~100 MHz.

8.5 W mode-locked Yb:Lu 1.5 Y 1.5 Al 5 O 12 laser with master oscillator power amplifiers

We report on a diode-pumped passively mode-locked Yb:Lu(1.5)Y(1.5)Al(5)O(12) (Yb:LuYAG) laser for the first time to our knowledge. With the mixed crystal of Yb:LuYAG as gain medium, the mode-locked laser generated 2.2 W of average output power with a repetition rate of 83.9 MHz and pulse duration of 2.4 ps at the wavelength of 1030 nm. In order to obtain higher output power, the output from the mode-locked oscillator was further amplified to 8.5 W by two-stage single-pass amplifiers. The high-power picosecond laser is very useful for applications such as pumping of midinfrared optical parametric oscillators, material microprocessing, and UV light generation.

Diode-Pumped Passively Mode-Locked Tm:

We report on a diode-pumped passively mode-locked picosecond Tm:CaGdAlO4 (Tm:CALGO) laser using a semiconductor saturable absorber mirror as the mode locker. With Tm:CALGO disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration of 27 ps, repetition rate of 128.6 MHz, and maximum average power of 330 mW at 1949.5 nm. To the best of our knowledge, this is the first demonstration of a mode-locked Tm:CALGO disordered crystal laser. The continuous-wave (CW) laser performance of Tm:CALGO was also investigated, and the maximum CW power was 730 mW. Our research results show that Tm:CALGO crystal is an excellent bulk medium for picosecond pulse generation at 2-μm wavelength.