Soliton mode-locked fiber laser based on topological insulator Bi2Te3 nanosheets at 2 μm

We reported diverse soliton operations in a thulium/holmium-doped fiber laser by taking advantage of a tapered fiber-based topological insulator（TI） Bi2Te3 saturable absorber（SA）.The SA had a nonsaturable loss of 53.5% and a modulation depth of 9.8%.Stable fundamentally mode-locked solitons at 1909.5 nm with distinct Kelly sidebands on the output spectrum,a pulse repetition rate of 21.5 MHz,and a measured pulse width of 1.26 ps were observed in the work.By increasing the pump power,both bunched solitons with soliton number up to 15 and harmonically mode-locked solitons with harmonic order up to 10 were obtained.To our knowledge,this is the first report of both bunched solitons and harmonically mode-locked solitons in a fiber laser at 2 μm region incorporated with TIs.

Dual-wavelength rectangular pulse erbium-doped fiber laser based on topological insulator saturable absorber

We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser(EDFL)with a topological insulator saturable absorber.The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state.In addition,we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser.Furthermore,by properly rotating the polarization controllers,the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained.The dual-wavelength rectangular pulse EDFL would benefit some potential applications,such as spectroscopy,biomedicine,and sensing research.

Passively Q-switched tri-wavelength Yb3+:GdAl3（BO3）4 solid-state laser with topological insulator Bi2Te3 as saturable absorber

In this paper,we reported a multiwavelength passively Q-switched Yb3+:GdAl3（BO3）4 solid-state laser with topological insulator Bi2Te3 as a saturable absorber（SA） for the first time,to the best of our knowledge.Bi2Te3 nanosheets were prepared by the facile solvothermal method.The influence of three Bi2Te3 densities on the laser operation was compared.The maximum average output power was up to 57 mW with a pulse energy of 511.7 nJ.The shortest pulsewidth was measured to be 370 ns with 110 kHz pulse repetition rate and 40 mW average power.The laser operated at three wavelengths simultaneously at 1043.7,1045.3,and 1046.2 nm,of which the frequency differences were within the terahertz wave band.Our work suggests that solvothermal synthesized Bi2Te3 is a promising SA for simultaneously multiwavelength laser operation.

Highlighting photonics: looking into the next decade

Let there be light-to change the world we want to be!Over the past several decades,and ever since the birth of the first laser,mankind has witnessed the development of the science of light,as light-based technologies have revolutionarily changed our lives.Needless to say,photonics has now penetrated into many aspects of science and technology,turning into an important and dynamically changing field of increasing interdisciplinary interest.In this inaugural issue of eLight,we highlight a few emerging trends in photonics that we think are likely to have major impact at least in the upcoming decade,spanning from integrated quantum photonics and quantum computing,through topological/non-Hermitian photonics and topological insulator lasers,to AI-empowered nanophotonics and photonic machine learning.This Perspective is by no means an attempt to summarize all the latest advances in photonics,yet we wish our subjective vision could fuel inspiration and foster excitement in scientific research especially for young researchers who love the science of light.