Boron quantum dots all-optical modulator based on efficient photothermal effect

All-optical devices without external electronic components have drawn extraordinary attentions in all-optical communication.In this work,boron quantum dots(BQDs)were synthesized by a facile liquid-phase exfoliation method.The as-prepared BQDs showed good structural homogeneity and crystallinity,broadband optical absorption as well as excellent photothermal properties.Femtosecond-resolved transient absorption further revealed the short carrier relaxation time of BQDs.Inspired by the outstanding photothermal properties and ultrafast carrier dynamic of BQDs,we fabricated BQDsbased all-optical modulator.The phase shift with a slope efficiency of 0.032π/m W and response time of 0.97 ms can be achieved.The modulator was used in laser resonance cavity to achieve all-optical actively Q-switched laser operation with control repetition rate.This prototypical BQDs-based all-optical modulator shows a great potential to be applied in all-optical information processing and communication.

MXene(TiNT):Synthesis,characteristics and application as a thermo-optical switcher for all-optical wavelength tuning laser

Single frequency fiber lasers have attracted intense attention in the high precision measure,optical communication and Raman spectroscopy due to their special features including narrow spectral linewidth,low-intensity noise and fiber compatibility[1-5].Tunable fiber lasers with broad wavelength-sweeping range or fast wavelength-sweeping speed have become key components in dense wavelength division multiplexing(DWDM)transmission systems or high-resolution spectroscopy.

Present advances and perspectives of broadband photo-detectors based on emerging 2D-Xenes beyond graphene

As an excellent optical device,photodetectors have many important applications,such as communication technology,display technology,scientific measurement,fire monitoring,aerospace and biomedical research,and ifs of great significance in the research of nanotechnology and optoelectronics.Graphene,as the first two-dimensional(2D)single-element nanomaterial,has the advantages of high carrier mobility,high strength,high light transmittance and excellent thermal conductivity,and ifs widely used in various nano-optical devices.The great success of graphene has led scientists to extensive research on other 2D single-element nanomaterials.Recently,a group of novel 2D single-element nanomaterials have attracted a lot of attention from scientists because of its excellent physical,chemical,electronic,mechanical and optical properties.Furthermore,it has opened a new door for the realization of new and efficient photodetectors.The group of 2D single-element nanomaterials are called 2D-Xenes and used to make high-performance photodetectors.Currently,there are few studies on photodetectors based on 2D-Xenes,but some 2D-Xenes have been applied to photodetectors and reported.Some of these have excellent photodetection performance,such as high photoresponsivity(R),broad spectral response range,fast photoresponse speed and high specific detectivity(D).Based on the novel 2D-Xenes,this review explores the types and preparation methods of 2D-Xenes,and the working mechanisms of 2D-Xenes photodetectors.Finally,the challenges and development trends of 2D-Xenes in the future are discussed.The research of 2D-Xenes is of great significance for the development of high-performance photodetectors in the future,and is expected to be widely used in other nanoelectronics and optical devices.

Ultrafast nonlinear absorption and nonlinear refraction in few-layer oxidized black phosphorus

We experimentally investigated the nonlinear optical response in few-layer oxidized black phosphorus(OBP) by the femtosecond Z-scan measurement technique, and found that OBP not only possesses strong ultrafast saturable absorption but also a nonlinear self-defocusing effect that is absent in black phosphorus(BP). The saturable absorption property originates mainly from the direct band structure, which is still maintained in OBP. The emergence of self-defocusing might originate from the combined consequences of the oxygen-induced defects in BP. Our experimental findings might constitute the first experimental evidence on how to dynamically tune its nonlinear property, offering an inroad in tailoring its optical properties through chemical modification(oxidation, introducing defects, etc.). The versatile ultrafast nonlinear optical properties(saturable absorption and self-defocusing) imply a significant potential of the layered OBP in the development of unprecedented optoelectronic devices, such as mode lockers, optical switches, laser beam shapers, and wavelength converters.

Graphene/phosphorene nano-heterojunction:facile synthesis, nonlinear optics, and ultrafast photonics applications with enhanced performance

Owing to its thickness-modulated direct energy band gap, relatively strong light–matter interaction, and unique nonlinear optical response at a long wavelength, few-layer black phosphorus, or phosphorene, becomes very attractive in ultrafast photonics applications. Herein, we synthesized a graphene/phosphorene nano-heterojunction using a liquid phase-stripping method. Tiny lattice distortions in graphene and phosphorene suggest the formation of a nano-heterojunction between graphene and phosphorene nanosheets. In addition, we systematically investigate their nonlinear optical responses at different wavelength regimes. Our experiments indicate that the combined advantages of ultrafast relaxation, broadband response in graphene, and the strong light–matter interaction in phosphorene can be combined together by nano-heterojunction. We have further fabricated two-dimensional(2D) nano-heterojunction based optical saturable absorbers and integrated them into an erbium-doped fiber laser to demonstrate the generation of a stable ultrashort pulse down to 148 fs. Our results indicate that a graphene/phosphorene nano-heterojunction can operate as a promising saturable absorber for ultrafast laser systems with ultrahigh pulse energy and ultranarrow pulse duration. We believe this work opens up a new approach to designing 2D heterointerfaces for applications in ultrafast photonics and other research.The fabrication of a 2D nano-heterojunction assembled from stacking different 2D materials, via this facile and scalable growth approach, paves the way for the formation and tuning of new 2D materials with desirable photonic properties and applications.

Broadband nonlinear optical response of graphdiyne for mid-infrared solid-state lasers

Graphdiyne(GDY),a novel all-carbon nanomaterial,is considered the most easily synthesized and stable carbon allotrope,positioning it as a promising photoelectric material.Herein,we successfully fabricated a high-quality GDY saturable absorber and saturable absorber mirror.Both broadband nonlinear saturable absorption and ultrafast relaxation dynamic properties in midinfrared region of the GDY were investigated.All solid-state diode-pumped short and ultrashort pulsed lasers were realized using the GDY absorber at wavelengths of 2 and 2.8μm,respectively.The results were then theoretically analyzed.This is the first presentation of ultrashort pulsed lasers in the mid-infrared region with GDY absorbers.These results resolutely confirm that GDY could be an optional broadband SA for all solid-state mid-infrared pulsed lasers,and they evidence its promising applications in mode-locked ultrafast lasers.

Light-induced tumor theranostics based on chemical-exfoliated borophene

Among 2D materials(Xenes)which are at the forefront of research activities,borophene,is an exciting new entry due to its uniquely varied optical,electronic,and chemical properties in many polymorphic forms with widely varying band gaps including the lightest 2D metallic phase.In this paper,we used a simple selective chemical etching to prepare borophene with a strong near IR light-induced photothermal effect.The photothermal efficiency is similar to plasmonic Au nanoparticles,with the added benefit of borophene being degradable due to electron deficiency of boron.We introduce this selective chemical etching process to obtain ultrathin and large borophene nanosheets(thickness of ~4 nm and lateral size up to ~600 nm)from the precursor of AlB_(2).We also report first-time observation of a selective Acid etching behavior showing HCl etching of Al to form a residual B lattice,while HF selectively etches B to yield an Al lattice.We demonstrate that through surface modification with polydopamine(PDA),a biocompatible smart delivery nanoplatform of B@PDA can respond to a tumor environment,exhibiting an enhanced cellular uptake efficiency.We demonstrate that borophene can be more suitable for safe photothermal theranostic of thick tumor using deep penetrating near IR light compared to gold nanoparticles which are not degradable,thus posing longterm toxicity concerns.With about 40 kinds of borides,we hope that our work will open door to more discoveries of this top-down selective etching approach for generating borophene structures with rich unexplored thermal,electronic,and optical properties for many other technological applications.