A newly designed grating used in terahertz region is proposed, which is composed of the trapezoidal elements repeated successively along one dimension of the substrate, and uniform interval （the grating period） repe...A newly designed grating used in terahertz region is proposed, which is composed of the trapezoidal elements repeated successively along one dimension of the substrate, and uniform interval （the grating period） repeated along the other dimension. The transmission of the grating owns a designable trapezoidal profile dependent on the geometric dimensions of the element. The far-field diffraction patterns of a designed grating at incident broadband terahertz frequencies, with element dimensions of upper, lower side and period of 50, 250, and 300 μm, respectively, are simulated by the scalar diffraction theory. The simulation results indicate that the terahertz grating exhibits a property of single-order diffraction, and the diffraction efficiency of the first order reaches 6.6%, exceeding that of a traditional sinusoidal amplitude grating with identical period and duty cycle. Owing to the regular architecture and the high single-order diffraction efficiency, the grating is easy to fabricate and shows great potential applications in single-shot spectral measurements of weak broadband terahertz pulse.展开更多
A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approxima...A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves.展开更多
The extreme ultraviolet and soft x-ray sources are widely used in various domains. Suppressing higher order harmonics and improving spectral purity are significant. This paper describes a novel method of higher order ...The extreme ultraviolet and soft x-ray sources are widely used in various domains. Suppressing higher order harmonics and improving spectral purity are significant. This paper describes a novel method of higher order harmonics suppression with single order diffraction gratings in extreme ultraviolet and soft x-ray. The principle of harmonic suppression with single order diffraction grating is described, and an extreme ultraviolet and soft x-ray non-harmonics grating monochromator is designed based on the single order diffraction grating. The performance is simulated by an optical design software. The emergent beams of a monochromator with different gratings are measured by a transmission grating spectrometer. The results show that the single order diffraction grating can suppress higher order harmonics effectively, and it is expected to be widely used in synchrotron radiation, diagnostics of laser induced plasma, and astrophysics.展开更多
Lines are induced on the surface of a photosensitive （FOTURAN） glass by focused femtosecond laser transverse writing with scanning velocity in a wide range of 40-1800 μm/s. The formed lines are analyzed using scann...Lines are induced on the surface of a photosensitive （FOTURAN） glass by focused femtosecond laser transverse writing with scanning velocity in a wide range of 40-1800 μm/s. The formed lines are analyzed using scanning electron microscope （SEM） and optical microscope （OM）. It is observed that three distinct morphologies of lines are produced depending on the scanning velocity. Lines written in low velocity level （40 - 100 μm/s） and high velocity level （1000 - 1800 μm/s） are uniform and regular, while those written in moderate velocity level （150 - 600 μm/s） are rough. The influence of scanning velocity is explained based on different pulses overlapping or cumulative dose of laser exposure in irradiated area. Fabrication of shallow groove on the surface is also demonstrated.展开更多
Micro-deposition of an aluminum film of 500-nm thickness on a quartz substrate was demonstrated by laser-induced forward transfer （LIFT） using a femtosecond laser pulse. With the help of atomic force microscopy （AF...Micro-deposition of an aluminum film of 500-nm thickness on a quartz substrate was demonstrated by laser-induced forward transfer （LIFT） using a femtosecond laser pulse. With the help of atomic force microscopy （AFM） and scanning electron microscopy （SEM）, the dependence of the morphology of deposited aluminum film on the irradiated laser pulse energy was investigated. As the laser fluence was slightly above the threshold fluence, the higher pressure of plasma for the thicker film made the free surface of solid phase burst out, which resulted in that not only the solid material was sputtered but also the deposited film in the liquid state was made irregularly.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB05033)the National Science Instruments Major Project of China(Grant No.2012YQ130125)
文摘A newly designed grating used in terahertz region is proposed, which is composed of the trapezoidal elements repeated successively along one dimension of the substrate, and uniform interval （the grating period） repeated along the other dimension. The transmission of the grating owns a designable trapezoidal profile dependent on the geometric dimensions of the element. The far-field diffraction patterns of a designed grating at incident broadband terahertz frequencies, with element dimensions of upper, lower side and period of 50, 250, and 300 μm, respectively, are simulated by the scalar diffraction theory. The simulation results indicate that the terahertz grating exhibits a property of single-order diffraction, and the diffraction efficiency of the first order reaches 6.6%, exceeding that of a traditional sinusoidal amplitude grating with identical period and duty cycle. Owing to the regular architecture and the high single-order diffraction efficiency, the grating is easy to fabricate and shows great potential applications in single-shot spectral measurements of weak broadband terahertz pulse.
基金Project supported by the Foundation of Science and Technology Development of China Academy of Engineering Physics(Grant No.2011B0102023)the Foundation of Plasma Physics Laboratory(Grant No.9140C680304110C6806)
文摘A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0206004)the National Natural Science Foundation of China(Grant No.11375160)the National Science Instruments Major Project of China(Grant No.2012YQ130125)
文摘The extreme ultraviolet and soft x-ray sources are widely used in various domains. Suppressing higher order harmonics and improving spectral purity are significant. This paper describes a novel method of higher order harmonics suppression with single order diffraction gratings in extreme ultraviolet and soft x-ray. The principle of harmonic suppression with single order diffraction grating is described, and an extreme ultraviolet and soft x-ray non-harmonics grating monochromator is designed based on the single order diffraction grating. The performance is simulated by an optical design software. The emergent beams of a monochromator with different gratings are measured by a transmission grating spectrometer. The results show that the single order diffraction grating can suppress higher order harmonics effectively, and it is expected to be widely used in synchrotron radiation, diagnostics of laser induced plasma, and astrophysics.
基金This work was supported by the Key Grant Project of the Ministry of Education,P.R.China(No.10410)the Science and Technology Development Project of Tianjin City (No.043103911)the National Natural Science Fundation of China(No.60608004)
文摘Lines are induced on the surface of a photosensitive （FOTURAN） glass by focused femtosecond laser transverse writing with scanning velocity in a wide range of 40-1800 μm/s. The formed lines are analyzed using scanning electron microscope （SEM） and optical microscope （OM）. It is observed that three distinct morphologies of lines are produced depending on the scanning velocity. Lines written in low velocity level （40 - 100 μm/s） and high velocity level （1000 - 1800 μm/s） are uniform and regular, while those written in moderate velocity level （150 - 600 μm/s） are rough. The influence of scanning velocity is explained based on different pulses overlapping or cumulative dose of laser exposure in irradiated area. Fabrication of shallow groove on the surface is also demonstrated.
基金This work was supported by the Key Grant Project of the Ministry of Education of China (No. 10410)the Science and Technology Development Project Fund of Tianjin (No. 043103911) the Science Research Start-Up Fund of Civil Aviation University (No. qd02x11).
文摘Micro-deposition of an aluminum film of 500-nm thickness on a quartz substrate was demonstrated by laser-induced forward transfer （LIFT） using a femtosecond laser pulse. With the help of atomic force microscopy （AFM） and scanning electron microscopy （SEM）, the dependence of the morphology of deposited aluminum film on the irradiated laser pulse energy was investigated. As the laser fluence was slightly above the threshold fluence, the higher pressure of plasma for the thicker film made the free surface of solid phase burst out, which resulted in that not only the solid material was sputtered but also the deposited film in the liquid state was made irregularly.
