Growth mechanism and photoluminescence of the SnO_2 nanotwists on thin film and the SnO_2 short nanowires on nanorods

SnO2 nanotwists on thin film and SnO2 short nanowires on nanorods have been grown on single silicon substrates by using Au-Ag alloying catalyst assisted carbothermal evaporation of SnO2 and active carbon powders. The morphology and the structure of the prepared nanostructures are determined on the basis of field-emission scanning electron microscopy （FESEM）, transmission electron microscopy （TEM）, selected area electronic diffraction （SAED）, high-resolution transmission electron microscopy （HRTEM）, x-ray diffraction （XRD）, Raman and photoluminescence （PL） spectra analysis. The new peaks at 356, 450, and 489 nm in the measured PL spectra of two kinds of SnO2 nanostructures are observed, implying that more luminescence centres exist in these SnO2 nanostructures due to nanocrystals and defects. The growth mechanism of these nanostructures belongs to the vapour liquid-solid （VLS） mechanism.

Withdrawal of Chinese Physics Letters 26 (2009) 114209 “A Sensitive Scheme to Observe Weak Photo-Refraction Effects in Some Nonlinear Optical Crystals Pumped by Ultrashort Optical Pulses”

This paper has been retracted because Fig.2 is copied from an earlier paper,“Interband photorefrac-tive effect in B-BBO crystal due to multiphoton ex-citation by intense ultrashort optical pulses”by Shix-iang Xu et al,which appeared in Optics Express 15(2007)10576,and its Figs.3 and 4 also present simi-lar data as in Figs.3 and 4 of the same Optics Express paper though they are measured at a different pump-ing power.

A Compact All-Solid-State 630-ps 9.43-kHz High Power Nd：YAG/Nd：YVO4 Hybrid Laser System

We present a simple and compact design for an all-solid-state laser amplifier system which can output 9.43-kHz 630-ps, 3.5-W pulse trains under 20 W absorbed pumping power. The excellent matching between the repetition of its seed source and the fluorescence lifetime of the amplifying medium makes it quiet efficient for the four-pass amplifier to be pumped in cw mode without need of any synchronization device between the oscillator and the amplifier. The entire setup just covers an area of 55 × 25 cm^2. The output average power fluctuation is less than ±1.5% within 10min and 3% within 6h.

A Sensitive Scheme to Observe Weak Photo-Refraction Effects in Some Nonlinear Optical Crystals Pumped by Ultrashort Optical Pulses

We present a sensitive scheme, for the first time to our knowledge, to observe photo-retraction （PR） ettects in some nonlinear optical crystals, e,g. β-BBO, LBO and BIBO, pumped by an intense ultrashort laser pulse chain. These quite weak effects are ＂amplified＂ by sensitive cw intraeavity loss modulation. Our results show that they are repeatable and are dependent on pumping power and wavelength, and their response time ranges from tens of seconds to several minutes. The recorded dynamical transitions between the self-focusing to the self-defocusing （or vice versa） induced by the PR effect may be critically important for us to give more insight into the stability of some cascade nonlinear frequency conversions, e.g. multi-stage optical parametric amplifiers.

Niobium telluride absorber for a mode-locked vector soliton fiber laser

Niobium telluride(NbTe_(2)),an emerging transition metal dichalcogenide material,has been theoretically predicted to have nonlinear absorption properties and excellent optical response.However,only a few studies of the utilization of NbTe_(2)in ultrafast photonics have been reported.In this work,a NbTe_(2)-based saturable absorber(SA)was applied in an erbium-doped fiber as a mode-locked device,and a vector soliton based on NbTe_(2)was obtained for the first time.NbTe_(2)-PVA film SA was successfully prepared by the liquid-phase exfoliation and spin coating methods,with a modulation depth of up to 10.87%.The nonlinear absorption coefficient of NbTe_(2)-based SA film tested through the open-aperture Z-scan laser measurement is 0.62×10^(−11) m/W.A conventional soliton with a pulse duration of 858 fs was generated using NbTe_(2)-based SA,which was demonstrated to be a kind of polarization-locked vector soliton in further investigation.Our experimental results reveal the nonlinear optical properties of NbTe_(2)and broaden its applications in ultrafast photonic devices.

Review and Prospect of Single-Shot Ultrafast Optical Imaging by Active Detection

In the recent decade,single-shot ultrafast optical imaging by active detection,called single-shot active ultrafast optical imaging(SS-AUOI)here,has made great progress,e.g.,with a temporal resolution of 50 fs and a frame rate beyond 10 trillion frames per second.Now,it has become indispensable for charactering the nonrepeatable and difficult-to-reproduce events and revealing the underlying physical,chemical,and biological mechanisms.On the basis of this delightful status,we would like to make a review of SS-AUOI.On the basis of a brief introduction of SS-AUOI,our review starts with discussing its characteristics and then focuses on the survey and prospect of SS-AUOI technology.

High-spatial-resolution ultrafast framing imaging at 15 trillion frames per second by optical parametric amplification

We report a framing imaging based on noncollinear optical parametric amplification(NCOPA),named FINCOPA,which applies NCOPA for the first time to single-shot ultrafast optical imaging.In an experiment targeting a laser-induced air plasma grating,FINCOPA achieved 50 fs-resolved optical imaging with a spatial resolution of^83 lp∕mm and an effective frame rate of 10 trillion frames per second(Tfps).It has also successfully visualized an ultrafast rotating optical field with an effective frame rate of 15 Tfps.FINCOPA has simultaneously a femtosecond-level temporal resolution and frame interval and a micrometer-level spatial resolution.Combining outstanding spatial and temporal resolutions with an ultrahigh frame rate,FINCOPA will contribute to high-spatiotemporal resolution observations of ultrafast transient events,such as atomic or molecular dynamics in photonic materials,plasma physics,and laser inertial-confinement fusion.