Enhancement of MoTe2 near-infrared absorption with gold hollow nanorods for photodetection

Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect bandgap in multilayer structures,degrades their performance when used as IR photodetectors.In this work,we utilize the fact that few-layer MoTe2 flake has a near-IR(NIR)bandgap and demonstrate a^60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface.Such gold hollow nanorods have distinct absorption peak located also at the NIR regime,therefore induces strong resonance,benefitting NIR absorption in MoTe2,resulting in strong near-field enhancement.With the evidence from steady and transient state optical spectra,we confirm that the enhancement of NIR response originates only photon absorption,rather than electron transport at interfaces as observed in other heterostructures,therefore,precluding the requirement of high-quality interfaces for commercial applications.

Modulation of the Anisotropic Electronic Properties in ReS_(2) via Ferroelectric Film

Anisotropic response in two-dimensional materials has emerged with attractive potential applications in angle-sensitive areas.However,the challenge with current studies on anisotropic response is due to the main use of the structural materials of pristine to examine the physical properties in different direc-tions,which cause restriction of the anisotropic ratio within a narrow range,thereby,limiting their practical applications.

Harmonic mode-locked fiber laser based on microfiber-assisted nonlinear multimode interference

A novel harmonic mode-locked fiber laser based on nonlinear multimode interference(NL-MMI) in a microfiber-assisted ultrafast optical switch is proposed in this Letter.The microfiber-assisted ultrafast optical switch can be obtained by tapering the splicing point of the graded-index multimode fiber(GIMF) and single-mode fiber,which not only helps to shorten the self-imaging period in GIMF to relax the strict requirement of NL-MMI on the length of multimode fiber,but also improves the harmonic order.In the experiment,with the waist diameter of ~15 μm,the repetition rates of the fiber laser can be stably locked at 285 MHz,corresponding to the 16 th-order harmonic mode-locking,with the pulse duration of 1.52 ps.Our results provide novel insight into the design of a high-repetition-rate laser and the application of microfibers in the modelocking device.

Vector dynamics of ultrafast cylindrical vector beams in a mode-locked fiber laser

The vector dynamics of solitons are crucial but easily neglected for realizing vortex solitons. In this Letter, we investigate the effect of vector dynamics on cylindrical vector beams(CVBs) implementation and propose a novel technical method to realize femtosecond CVBs based on vector-locked solitons, which are presented as group-velocity-locked vector solitons(GVLVSs) in the experiment. The outstanding vector properties of GVLVSs not only greatly improve the efficiency of solitons converted into CVBs and output power of CVBs(2.4 times and 4.1 times that of scalar solitons and vector change periodical solitons, with the purity of 97.2%), but also relax the obstacle of ultrafast CVBs from the fundamental frequency to the harmonic regime(up to 198 MHz) for the first time, to the best of our knowledge. This is the highest repetition rate reported for ultrafast CVBs based on passive mode-locking. The investigation of the influence of solitons vector dynamics evolution on the realization of CVBs provides guidance for the excellent performance of ultrafast CVBs.