Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
Not a member yet
13355 research outputs found
Sort by
307 W high-power 1018 nm monolithic tandem pump fiber source with effective thermal management
No full textNational Key Research and Development Program of China [2016YFB0402201]; National Natural Science Foundation of China [U1330134, 6130824, 61377062]; Natural Science Foundation of Shanghai [16ZR1440100, 16ZR1440200]; Primary Research & Development Plan of Jiangsu [BE2016005-4]; Key Project of Science and Technology of Jiangsu [BE2014001-2]We report a 307 W 1018 nm Yb-doped fiber laser pumped by a single 976 nm laser diode. The cavity slope efficiency is up to 75.9% and the amplified spontaneous emission is suppressed by 54 dB. The beam quality of the output laser has an M-2 factor of 1.17. Effective thermal management is considered to ensure the stable operation of our system. The power stability at the maximum output power level is measured during a period of 0.5 h and the power fluctuation is less than 0.8%. This architecture can be an effective high brightness pump source of core-pumping high-power fiber amplifiers
Filamentation-induced bulk modification in fused silica by excimer laser
No full textNational Natural Science Foundation [61308024, 61405202]; National Science and Technology Major Project [2013ZX02202003]; National Key Research and Development Program [2016YFB0402201]; K. C. Wong Education Foundation; Program of Shanghai Technology Research Leader [17XD1424800]; Shanghai Sailing Program [17YF1421200]; Key technologies R& D program of Jiangsu [BE2014001, BE20160054]; Natural Science Foundation of Shanghai [16ZR1440100, 16ZR1440200]Filamentary propagation and laser-induced damage have been demonstrated and investigated in fused silica excited by nanosecond deep-ultraviolet laser pulses. Long-range modification channels, up to 10 mm because of the filamentation and defect absorption in the bulk of the solid transparent materials, are observed. Here we investigate ways to control these laser-induced modifications by varying the laser pulse energy and number of exposures. The effects of objective lens focal length and working distance on the filament and modification are also discussed. Furthermore, the laser-induced fluorescence spectra indicate that dense absorbing defects in the damaged regions. Moreover, the mitigation of the induced damage through thermal effects are discussed
High brightness, high SNR radio-frequency signal generated by an all-fibered linear-polarization single-mode dual-frequency fiber laser
No full textNational Natural Science Foundation of China (NSFC) [61405202, 61705243]; National Science Foundation of Shanghai [16ZR1440100, 16ZR1440200]; Program of Shanghai Technology Research Leader [17XD1424800]; Shanghai Sailing Program [17YF1421200]; Key Technologies R&D Program of Jiangsu [BE2016005-4]; K. C. Wong Education FoundationA high brightness, high signal-to-noise ratio (SNR) linear-polarization optically generated radio-frequency signal is demonstrated based on an all-fibered master oscillator power amplifier (MOPA) configuration. The seed signal is generated by beating two different frequency beams which are split from the same single frequency laser source. One beam has initial frequency and the other beam is shifted by 200 MHz using an acoustic-optical modulator. The combined beam contains two frequency components with a frequency difference of 200 MHz and this dual-frequency laser signal is then amplified by a three-stage all-fibered amplifier. In order to obtain high brightness output, a single mode fiber with 10 mu m core diameter is adopted in the amplifier chain. A designed step-distribution strain is applied on the active fiber for the suppression of stimulated Brillouin scattering (SBS) effect. As a result, up to 143 W output power is achieved with the slop efficiency of 81.4%. The beam quality factors (M-2) are measured to 1.06 (M-x(2)) and 1.04 (M-y(2)) and the SNR is up to 54.7 dB. These two frequency components with a certain frequency gap can be identically amplified via the fiber amplifier and the beat note stability, modulation depth as well as SNR are well maintained before and after amplification. To the best of our knowledge, this is the highest reported brightness of the optically generated radio-frequency signal
Review of recent progress on single-frequency fiber lasers [Invited]
No full textNational Natural Science Foundation of China (NSFC) [61275102, 61335013]; National High Technology Research and Development Program [2014AA041901]; National Basic Research Program of China [2014CB3399802]; Regional Demonstration Projects of Ocean Economic Innovation Development [cxsf2014-21]; Doctoral Fund of Ministry of Education [20130032110051]Single-frequency fiber lasers have drawn intense attention for their extensive applications from high-resolution spectroscopy and gravitational wave detection to materials processing due to the outstanding properties of low noise, narrow linewidth, and the resulting long coherence length. In this paper, the recent advances of single-frequency fiber oscillators and amplifiers are briefly reviewed in the broad wavelength region of 1-3 mu m. Performance improvements in laser noise and linewidth are addressed with the newly developed physical mechanisms. The solution to achieving higher power/energy is also discussed, accompanied by the start-of-the-art results achieved to date. (C) 2017 Optical Society of Americ
Measurement precision improvement for excimer laser pulse energy sensor based on a special finite impulse response filter
No full textIn deep ultraviolet lithographic tools, precise measurement of excimer laser pulse energy is essential. However, system noise of the energy sensor, which is used to monitor the laser pulse during exposure dose control, complicate pulse energy measurement. To improve measurement precision, a specific finite impulse response filter is proposed for signal denoising. Particularly, the convolution kernel of the specific finite impulse response filter is derived from the nonlinear fitting of the energy sensor output. Experimental results show that the measurement precision of the energy sensor improves 2-3 times with the specific finite impulse response filter. To verify the effectiveness of the energy sensor, it is used for transmittance measurement; the measurement result of a Corning 7980 witness sample is consistent with that measured by a commercial ultraviolet spectrophotometer and the measurement accuracy is 0.11% (k = 2)
On the difference between single- and double-sided bandpass filtering of spatial frequencies
No full textNational Natural Science Foundation of China [61405214, 61308077]It is well-known that bandpass filtering will lead to edge extraction in image processing. However, the difference between single-and double-sided bandpass filtering has never been compared and investigated in the literature. We investigate the difference between single-and double-sided bandpass spatial filtering in a 4-f coherent optical image processing system. We find that single-sided filtering can approximate the operation of a first-order derivative, while double-sided filtering gives a second-order derivative. Simulations and optical experiments confirm our findings
Coulomb interaction-induced jitter amplification in RF-compressed high-brightness electron source ultrafast electron diffraction
No full textNational Natural Science Fund [51132004, 11474096]; Shanghai Municipal Science and Technology Commission [14JC1401500]We have theoretically and experimentally demonstrated an RF compression-based jitter-amplification effect in high-brightness electron source ultrafast electron diffraction (UED), which degrades the temporal resolution significantly. A detailed analysis and simulations reveal the crucial role of the longitudinal and transverse Coulomb interaction for this jitter-amplification effect, which accord very well with experimental results. An optimized compact UED structure for full compression has been proposed, which can suppress the jitter by half and improve the temporal resolution to sub-100 fs. This Coulomb interaction-induced jitter amplification exists in nearly the whole ultrafast physics field where laser-electron synchronization is required. Moreover, it cannot be suppressed completely. The quantified explanation for the mechanism and optimization provides important guidance for photocathode accelerators and other compression-based ultrashort electron pulse generation and precise control
Femtosecond-laser-driven wire-guided helical undulator for intense terahertz radiation
No full textNational Natural Science Foundation of China [11425418, 11127901, 61521093, 11405244]; Shanghai Natural Science Funds [14ZR1444800]; Strategic Priority Research Program [XDB16]; State Key Laboratory Program of Chinese Ministry of Science and Technology; Key Laboratory for Laser Plasmas (Ministry of Education); Shanghai Jiao Tong University; National Basic Research Program of China [2014CB339802]The capability of synchrotron radiation to produce ultrabright emission has attracted considerable interest over the last half a century. To date, magnetic undulators with a period of several centimetres are commonly used for wiggling relativistic electrons in a modulated field. Here, we propose a novel compact undulator with a period down to the submillimetre level based on a spontaneous electric field that is driven by a femtosecond laser. Both the guided energetic electrons and the gyrotron-like undulator are spontaneously produced by irradiating a thin metallic wire with an intense laser pulse. An intense radial electric field instantaneously created on the wire can guide the electrons' helical motion along the wire and induce periodic THz emission. We have demonstrated that this scheme can produce intense THz sources with a conversion efficiency of 1% that are frequency-tunable by adjusting the diameter of the wire. Amplified emission of THz radiation by more than tenfold has been observed
Propagation effects in the generation process of high-order vortex harmonics
No full textNational Natural Science Foundation of China [11374318, 11674312, 61775087]; Natural Science Foundation of Jiangsu [BK20161159]We numerically study the propagation of a Laguerre-Gaussian beam through polar molecular media via the exact solution of full-wave Maxwell-Bloch equations where the rotating-wave and slowly-varying-envelope approximations are not included. It is found that beyond the coexistence of odd-order and even-order vortex harmonics due to inversion asymmetry of the system, the light propagation effect results in the intensity enhancement of a high-order vortex harmonics. Moreover, the orbital momentum successfully transfers from the fundamental laser driver to the vortex harmonics which topological charger number is directly proportional to its order
Self-Referenced Spectral Interferometry for Femtosecond Pulse Characterization
No full textNational Natural Science Foundation of China (NSFC) [11274327, 61521093, 61527821]; Chinese Academy of Sciences [YZ201538, XDB160106]Since its introduction in 2010, self-referenced spectral interferometry (SRSI) has turned out to be an analytical, sensitive, accurate, and fast method for characterizing the temporal profile of femtosecond pulses. We review the underlying principle and the recent progress in the field of SRSI. We present our experimental work on this method, including the development of self-diffraction (SD) effect-based SRSI (SD-SRSI) and transient-grating (TG) effect-based SRSI (TG-SRSI). Three experiments based on TG-SRSI were performed: (1) We built a simple TG-SRSI device and used it to characterize a sub-10 fs pulse with a center wavelength of 1.8 mu m. (2) On the basis of the TG effect, we successfully combined SRSI and frequency-resolved optical gating (FROG) into a single device. The device has a broad range of application, because it has the advantages of both SRSI and FROG methods. (3) Weak sub-nanojoule pulses from an oscillator were successfully characterized using the TG-SRSI device, the optical setup of which is smaller than the palm of a hand, making it convenient for use in many applications, including sensor monitoring the pulse profile of laser systems. In addition, the SRSI method was extended for single-shot characterization of the temporal contrast of ultraintense and ultrashort laser pulses