Shouqian Tang's research while affiliated with Shandong University of Technology and other places

We demonstrate a passively mode-locked fiber laser employing zirconium telluride (ZrTe 2 ) as saturable absorber and illustrate its application for vector soliton generation in erbium-doped fiber lasers. By tuning the pump power and polarization controller, stable mode-locked operations in different operations are obtained with different cavity lengths. In addition, we also further research on characteristics of the vector solitons formed in fiber laser. The vector features of the obtained solitons are experimentally explored, and these solitons are proved to be group velocity locked vector solitons. Our research results indicate that ZrTe 2 nanosheets could be available saturable absorber for ultrashort pulse fiber lasers, especially for generating vector soliton pulses in fiber lasers.

High-energy Er-doped fiber laser with high conversion efficiency is reported, which is mode-locked by a germanium telluride (GeTe)-based saturable absorber (SA). By adjusting the direction of the polarization controller (PC), a high-energy pulse with a central wavelength of 1533.1 nm and a fundamental repetition frequency of 1.58 MHz is achieved. Under the pump power of 450.1 mW, the maximum average output power is 50.48 mW, and the single-pulse energy is 32 nJ. It is worth noting that the optical-to-optical conversion efficiency has reached about 11.2%. The experimental results indicate that GeTe performs excellently as SAs for obtaining mode-locked fiber lasers and plays an extremely important role in high-energy fiber lasers.

We proposed an erbium-doped fiber laser mode-locked with a Mo x W1-xTe2-based nonlinear optical modulator for the first time to our best knowledge. This fiber laser can deliver bright pulses, bright-dark pulse pairs, dark pulses, bright-dark-bright pulses, and dark-dark-bright pulses. The modulation depth and saturation intensity of the Mo x W1-xTe2-based saturable absorber were about 7.8% and 8.6 MW/cm², respectively. When 10% of the laser in the cavity was output, conventional soliton pulses with central wavelength of 1560.1 nm can be obtained in the cavity. When 70% of the laser was output, dual-wavelength domain-wall dark pulses appeared in the laser cavity. This experiment revealed that an appropriate increase in the ratio of output energy can improve the chance of dark pulses in fiber lasers. The mode-locking states in this fiber laser can evolve with each other between bright pulses, bright-dark pulse pairs and dark pulses by adjusting the polarization controller. The results indicated that the Mo x W1-xTe2 can be used to make modulators for generating dark pulses. Furthermore, our work will be of great help to improve the chance of the generation of dark pulse in fiber lasers.

In this paper, an indium antimonide (InSb) saturable absorber (SA) was successfully fabricated. The saturable absorption properties of the InSb SA were studied, and they show a modulation depth and a saturable intensity of 5.17% and ${9.23}\;{\rm{MW/c}}{{\rm{m}}^2}$ 9.23 M W / c m 2 , respectively. By employing the InSb SA and building the ring cavity laser structure, the bright–dark soliton operations were successfully obtained by increasing the pump power to 100.4 mW and adjusting the polarization controller. As the pump power increased from 100.4 to 180.3 mW, the average output power increased from 4.69 to 9.42 mW, the corresponding fundamental repetition rate was 2.85 MHz, and the signal-to-noise ratio was 68 dB. The experimental results show that InSb with excellent saturable absorption characteristics can be used as a SA to obtain pulse lasers. Therefore, InSb has important potential in fiber laser generation, further applications in optoelectronics, laser distance ranging, and optical fiber communication, and it can be widely developed.

In this work, we fabricate a saturable absorber based on GeTe with saturation intensity and modulation depth of ${12.6}\;{{\rm MW/cm}^2}$ 12.6 M W / c m 2 and 7%, respectively. We obtain stable conventional soliton and stretched soliton mode-locking operation. For the conventional soliton state, the average output power increased from 0.93 to 8.70 mW with the increase of pump power, and the fundamental repetition rate was 7.8351 MHz. Its central wavelength and 3 dB bandwidth were 1564.72 and 4.78 nm, respectively. For the stretched soliton state, when the pump power was increased from 87.4 to 420.3 mW, the average output power increased from 2.05 to 10.46 mW. When the maximum average output power reached 10.46 mW, the maximum average single-pulse energy was 0.86 nJ. The experimental results show that GeTe nanosheets will have broad application potential in the field of ultrafast photonics.

In our work, a new-type, to the best of our knowledge, ferromagnetic insulator and its nonlinear optical absorption characteristics and related ultrafast modulation applications were investigated. ${{\rm Cr}_2}{{\rm Si}_2}{{\rm Te}_6}$ C r 2 S i 2 T e 6 saturable absorbers (SAs) with a modulation depth and a saturable intensity of 9.7% and ${3.5}\;{{\rm MW/cm}^2}$ 3.5 M W / c m 2 were fabricated. By adjusting the pump power to 120 mW and optimizing the polarization state, traditional soliton operations were obtained successfully; the corresponding duration of pulse and the fundamental repetition rate were ${\sim} {1.33}\;{\rm ps}$ ∼ 1.33 p s and 6.70 MHz, and the signal-to-noise ratio was 50 dB. The experimental results reveal that ${{\rm Cr}_2}{{\rm Si}_2}{{\rm Te}_6}$ C r 2 S i 2 T e 6 with excellent saturable absorption characteristics can be used as a SA to obtain ultrafast pulse lasers.