Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kH...Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kHz range,and their micromirror-free configuration simplifies the fabrication process and reduces costs compared to micromirror-based modulators.However,these modulators are limited in their optical efficiency and aperture.Here,we present a MEMS grating modulator with a notably extendable aperture and a high optical efficiency that benefits from the adoption of a tunable sinusoidal grating.Instead of end-constrained movable ribbons,we constrain the MEMS grating modulator through broadside-constrained continuous ribbons.The end-free grating enables improved scalability along the ribbons,and the continuous sinusoidal surface of the grating allows an increased fill factor.As an example,we experimentally demonstrate a MEMS grating modulator with a large-scale aperture of 30×30 mm and an optical efficiency of up to 90%.The modulation depth enables intensity modulation across a broad wavelength range from 635 to 1700 nm.The experimental results demonstrate that the reported modulator has a mechanical settling time of 1.1μs and an extinction ratio of over 20 dB.Furthermore,it offers a dynamic modulation contrast of over 95%within a 250 kHz operating frequency and achieves full modulation within a field of view(FOV)of±30°.The reported MEMS grating modulator holds promise for application in high-speed light attenuation and modulating retroreflector free-space optical(MRR-FSO)communication systems.Our device also paves new ways for future high-speed,energyefficient,and cost-effective communication networks.展开更多
A composite one-dimensional （1D） Ag sinusoidal nanograting aiming at label-free surface enhanced Raman scattering （SERS） detection of TNT with robust and reproducible enhancements is discussed. 1D periodic sinusoi...A composite one-dimensional （1D） Ag sinusoidal nanograting aiming at label-free surface enhanced Raman scattering （SERS） detection of TNT with robust and reproducible enhancements is discussed. 1D periodic sinusoidal SiO2 grating followed by Ag evaporation is proposed for the creation of reproducible and effective SERS substrate based on surface plasmon polaritons （SPPs）. The optimal structure of 1D sinusoidal nanograting and its long-range SERS effect are analyzed by using the finite difference time domain （FDTD）. Simulation SERS enhancement factor （EF） can be 5 orders of magnitude as possible. This SERS substrate is prepared by the interference photolithography technology, its SERS performance is tested by Rh6G detection experiments, and the actual test EF is about 10. The label-free SERS detection capacity of TNT is demonstrated in the experiment.展开更多
A novel wavefront sensing method based on phase contrast theory and coherent optical processing is proposed. The wavefront gradient field in the object plane is modulated into intensity distribution in a gang of patte...A novel wavefront sensing method based on phase contrast theory and coherent optical processing is proposed. The wavefront gradient field in the object plane is modulated into intensity distribution in a gang of patterns, making highdensity detection available. By applying the method, we have also designed a wavefront sensor. It consists of a classical coherent optical processing system, a CCD detector array, two pieces of orthogonal composite sinusoidal gratings, and a mechanical structure that can perform real-time linear positioning. The simulation results prove and demonstrate the validity of the method and the sensor in high-precision measurement of the wavefront gradient field.展开更多
In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to im...In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.展开更多
In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensiv...In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant No.U21B2035,51575455,51175436,62105265,and 62475219)the Fundamental Research Funds for the Central Universities(G2023KY05104).
文摘Microelectromechanical system(MEMS)grating modulators enable versatile beam steering functions through the electrostatic actuation of movable ribbons.These modulators operate at ultrahigh frequencies in the hundred kHz range,and their micromirror-free configuration simplifies the fabrication process and reduces costs compared to micromirror-based modulators.However,these modulators are limited in their optical efficiency and aperture.Here,we present a MEMS grating modulator with a notably extendable aperture and a high optical efficiency that benefits from the adoption of a tunable sinusoidal grating.Instead of end-constrained movable ribbons,we constrain the MEMS grating modulator through broadside-constrained continuous ribbons.The end-free grating enables improved scalability along the ribbons,and the continuous sinusoidal surface of the grating allows an increased fill factor.As an example,we experimentally demonstrate a MEMS grating modulator with a large-scale aperture of 30×30 mm and an optical efficiency of up to 90%.The modulation depth enables intensity modulation across a broad wavelength range from 635 to 1700 nm.The experimental results demonstrate that the reported modulator has a mechanical settling time of 1.1μs and an extinction ratio of over 20 dB.Furthermore,it offers a dynamic modulation contrast of over 95%within a 250 kHz operating frequency and achieves full modulation within a field of view(FOV)of±30°.The reported MEMS grating modulator holds promise for application in high-speed light attenuation and modulating retroreflector free-space optical(MRR-FSO)communication systems.Our device also paves new ways for future high-speed,energyefficient,and cost-effective communication networks.
文摘A composite one-dimensional （1D） Ag sinusoidal nanograting aiming at label-free surface enhanced Raman scattering （SERS） detection of TNT with robust and reproducible enhancements is discussed. 1D periodic sinusoidal SiO2 grating followed by Ag evaporation is proposed for the creation of reproducible and effective SERS substrate based on surface plasmon polaritons （SPPs）. The optimal structure of 1D sinusoidal nanograting and its long-range SERS effect are analyzed by using the finite difference time domain （FDTD）. Simulation SERS enhancement factor （EF） can be 5 orders of magnitude as possible. This SERS substrate is prepared by the interference photolithography technology, its SERS performance is tested by Rh6G detection experiments, and the actual test EF is about 10. The label-free SERS detection capacity of TNT is demonstrated in the experiment.
文摘A novel wavefront sensing method based on phase contrast theory and coherent optical processing is proposed. The wavefront gradient field in the object plane is modulated into intensity distribution in a gang of patterns, making highdensity detection available. By applying the method, we have also designed a wavefront sensor. It consists of a classical coherent optical processing system, a CCD detector array, two pieces of orthogonal composite sinusoidal gratings, and a mechanical structure that can perform real-time linear positioning. The simulation results prove and demonstrate the validity of the method and the sensor in high-precision measurement of the wavefront gradient field.
基金supported by the National Natural Science Foundation of China(Nos.60808020 and 61078041)the National Science and Technology Support(No.2014BAH03F01)+1 种基金the Tianjin Research Program of Application Foundation and Advanced Technology(No.10JCYBJC07200)the Technology Program of Tianjin Municipal Education Commission(No.20130324)
文摘In the three-dimensional(3D) contour measurement,the phase shift profilometry(PSP) method is the most widely used one.However,the measurement speed of PSP is very low because of the multiple projections.In order to improve the measurement speed,color grating stripes are used for measurement in this paper.During the measurement,only one color sinusoidal fringe is projected on the measured object.Therefore,the measurement speed is greatly improved.Since there is coupling or interference phenomenon between the adjacent color grating stripes,a color correction method is used to improve the measurement results.A method for correcting nonlinear error of measurement system is proposed in this paper,and the sinusoidal property of acquired image after correction is better than that before correction.Experimental results show that with these correction methods,the measurement errors can be reduced.Therefore,it can support a good foundation for the high-precision 3D reconstruction.
基金supported by the National Natural Science Foundation of China(Nos.11974314 and 11674288).
文摘In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.
