Yiran Wang

Multi-layered black phosphorus as saturable absorber for pulsed Cr:ZnSe laser at 2.4 μm

A high-quality black phosphorus (BP) saturable-absorber mirror (SAM) was successfully fabricated with the multi-layered BP, prepared by liquid-phase exfoliation (LPE) method. The modulation depth and saturation power intensity of BP absorber were measured to be 10.7% and 0.96 MW/cm(2), respectively. Using the BP-SAM, we experimentally demonstrated the mid-infrared (mid-IR) pulse generation from a BP Q-switched Cr:ZnSe laser for the first time to our best knowledge. Stable Q-switched pulse as short as 189 ns with an average output power of 36 mW was realized at 2.4 μm, corresponding to a repetition rate of 176 kHz and a single pulse energy of 205 nJ. Our work sufficiently validated that multi-layer BP could be used as an optical modulator for mid-IR pulse laser sources.

Femtosecond solid-state laser based on a few-layered black phosphorus saturable absorber.

In this Letter, a high-quality, few-layered black phosphorus (BP) saturable absorber (SA) was fabricated successfully, and a femtosecond solid-state laser modulated by BP-SA was experimentally demonstrated for the first time, to the best of our knowledge. Pulses as short as 272 fs were achieved with an average output power of 0.82 W, corresponding to the pulse energy of 6.48 nJ and peak power of 23.8 MW. So far, these represent the shortest pulse duration and highest output power ever obtained with a BP-based mode-locked solid-state laser. The results indicate the promising potential of few-layered BP-SA for applications in solid-state femtosecond mode-locked lasers.

Few-layered ReS 2 as saturable absorber for 2.8 μm solid state laser

A novel two-dimensional (2D) material member in the transition metal dichalcogenides family, few-layered rhenium disulfide (ReS2) was prepared by liquid phase method successfully. By using the open-aperture Z-scan method, the saturable absorption properties at 2.8xa0μm were characterized with a saturable fluence of 22.6u2009u2009μJ/cm2 and a modulation depth of 9.7%. A passively Q-switched solid-state laser at 2.8xa0μm was demonstrated by using the as-prepared ReS2 saturable absorber successfully. Under an absorbed pump power of 920xa0mW, a maximum output power of 104xa0mW was obtained with a pulse width of 324xa0ns and a repetition rate of 126xa0kHz. To the best of our knowledge, this is the first demonstration of applying ReS2 in an all-solid-state laser. Moreover, this represents the shortest pulses in Q-switched MIR lasers based on a 2D material as the saturable absorber, which demonstrated the superiority of ReS2 acting as an optical modulator for generating short-pulsed lasers. The results well prove that 2D ReS2 is a reliable optical modulator for MIR solid-state lasers.

Triwavelength synchronously mode-locked fiber laser based on few-layered black phosphorus

A triwavelength synchronously mode-locked erbium-doped fiber laser with black phosphorus (BP) was demonstrated. The BP was proved to be not only an excellent saturable absorber (SA) but also a strong nonlinear material benefiting the stabilization of a multiwavelength fiber laser. The laser worked for a long time at three synchronous wavelengths of 1557.2, 1557.7, and 1558.2 nm. The autocorrelation trace of 9.41 ps pulses showed an interference beating of 0.06 THz, corresponding to a beating period of 16.37 ps. To the best of our knowledge, this is the first report on the usage of BP as an SA for building a multiwavelength synchronous mode-locked fiber laser.

Passively mode-locked 1.34 μm bulk laser based on few-layer black phosphorus saturable absorber

By using few-layer black phosphorus (BP) as saturable absorber, an efficient mode-locked Nd:GdVO4 bulk laser operating at 1.34 μm was realized. An average output power of 350 mW was achieved with a slope efficiency of 15%. The corresponding mode-locking pulse repetition rate, pulse duration and pulse energy were 58.14 MHz, 9.24 ps and 3.0 nJ, respectively. To the best of our knowledge, the pulse width is the shortest among the mode-locked 1.34 μm neodymium lasers ever obtained with other two-dimensional materials saturable absorber. The results clearly indicate the few-layered BP is a kind of promising saturable absorber for ultrafast 1.34 μm lasers.

High power single-frequency Innoslab amplifier.

A laser diode array (LDA) end-pumped continuous-wave single-frequency Innoslab amplifier has been demonstrated. The Gaussian ray bundle method was used to model the light propagation in the Innoslab amplifier for the first time to the best of our knowledge. With discrete reflectors, the maximum output of 60 W with a linewidth of 44 MHz was achieved under the pump power of 245 W, corresponding to the optical-optical efficiency of 24.5%. The beam quality factor M2 at the output power of 51 W in the horizontal and vertical direction was measured to be 1.4 and 1.3, respectively. The long-term power instability in 2 h was less than 0.25%.

Tunable High-Power Q-Switched Fiber Laser Based on BP-PVA Saturable Absorber

Black phosphors (BP) nano-materials have been extensively investigated in the past years. However, the character of easily oxidizable limits BPs stability. Here a long-term-stable tunable Q-switched fiber laser with BP polymer composite (polyvinyl alcohol, PVA) as saturable absorber is realized. The modulation depth and the saturation power intensity of the BP-PVA film are 8.3% and 7.9xa0MW/cm2, respectively. A high average output power of 12.03xa0mW is obtained under the pump power of 400xa0mW. The shortest pulse width and maximum single pulse energy are 1.365xa0μs and 148.63xa0nJ, respectively. Meanwhile, the output spectra have a 2.5-nm blue shift when the pump power increases. The results prove that as a Q-switcher, BP polymer composite has a good performance on high power and excellent stability pulsed laser.

Third-order nonlinearity and saturable absorbed performance of Cr 4+ :Gd 3 Ga 5 O 12 crystal

In this work, the third-order nonlinear optical properties and saturable absorbed performance of Cr4+-doped Gd3Ga5O12 (Cr4+:GGG) crystal were investigated. By using the Z-scan technique, the third-order nonlinear properties were analyzed systematically. Compared with Cr4+:YAG crystal, Cr4+:GGG crystal has a large third-order nonlinear refractive index, ground-state absorption, and excited-state absorption cross section. It has been successfully employed as a saturable absorber for passively Q-switched and Q-switching mode-locked lasers in this paper. In the Q-switched regime, the maximum average output power of 600 mW was obtained with the shortest pulse width of 4.76 ns and the repetition rate of 41.4 kHz, corresponding to single pulse energy and pulse peak power of 14.5 µJ and 3 kW, respectively. For the Q-switching mode-locking operation, the maximum output power of 468 mW was obtained with a repetition rate of 141.2 MHz. The results indicate that Cr4+:GGG crystal has the potential to be used for passive Q-switching and mode-locking laser generation.

760 fs diode-pumped mode-locked laser with Yb:LuAG crystal at 1032 nm.

In this study, we experimentally demonstrate the generation of 760xa0fs pulse duration from a diode-pumped Yb:LuAG mode-locked laser at 1032xa0nm. At the repetition rate of 58.6xa0MHz, the maximum average power of 1.07xa0W was obtained, corresponding to the peak power of 24xa0kW. To our knowledge, these results represent the shortest pulse duration and highest peak power ever obtained for a 1032xa0nm mode-locked laser with Yb:LuAG crystal.

Few-layer TiSe 2 as a saturable absorber for nanosecond pulse generation in 2.95 μm bulk laser

1T-phase titanium diselenide (1T-TiSe2), a model two-dimensional (2D) transition metal dichalcogenide, has attracted much attention due to its intriguing electrical and optical properties. In this work, a 1T-TiSe2-based high-quality large-area saturable absorber (SA) (1T-TiSe2-SA) was successfully fabricated with the liquid-phase exfoliation method. With the as-prepared 1T-TiSe2-SA, a stable, passively Q-switched laser operating at 2.95xa0μm was first realized. Under an absorbed pump power of 3.35xa0W, the maximum average output power was 130xa0mW with a slope efficiency of 5%. A pulse width of 160.5xa0ns was obtained, which is the shortest among 3.0xa0μm passively Q-switched lasers ever achieved with 2D materials as SAs, to the best of our knowledge. The results indicate that 1T-TiSe2 is a promising alternative as a nonlinear optical modulator for short-pulse laser generation near the 3.0xa0μm mid-infrared region.