We demonstrate a high-speed swept-source optical coherence tomography (SS-OCT) system, which is based on a high-speed swept light source and a Mach-Zehnder interferometer with a high-speed photodetector. The light sou...We demonstrate a high-speed swept-source optical coherence tomography (SS-OCT) system, which is based on a high-speed swept light source and a Mach-Zehnder interferometer with a high-speed photodetector. The light source is an external-cavity laser tuned by a KTN electro-optic deflector, which exhibits a very fast response and large deflection. The scanning wavelength range is almost 80 nm up to 200 kHz with a ±400-V deflector driving voltage. The system acquires 1 mm × 1 mm images consisting of 200 × 200 pixels within few milliseconds. We present preliminary SS-OCT images of an in-vitro human nail and an in-vivo finger pad.展开更多
We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid.The essence of this multiple frequency conversion is four-wave mixing based on stored ato...We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid.The essence of this multiple frequency conversion is four-wave mixing based on stored atomic spin coherence.Through electromagnetically induced transparency,an input probe pulse is stored into atomic spin coherence by modulating the intensity of the control field.By using two different control fields to interact with the coherently prepared medium,the stored atomic spin coherence can be transformed into three different information channels.Multiple frequency conversion is implemented efficiently by manipulating the spectra of the control fields to scatter atomic spin coherence.This multiple frequency conversion is expected to have potential applications in information processing and communication network.展开更多
The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theo...The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theoretical model, the effects of grain height, its density, the band width and spectral distribution of the line profile (Gaussian and Lorentzian) illuminating a rough surface on the visibility of speckle pattern are investigated. An experimental setup was constructed to study the effect of surface roughness and coherence of the illuminating light beam on the contrast of speckle pattern. The general behavior of the experimental results, which agree with published data, is compatible with the new theoretical model.展开更多
Starting from the Rayleigh-Sommerfeld diffraction integral,this paper studies the spectral behavior in Young's experiment illuminated by nonparaxial partially coherent light and compares with the paraxial case,whe...Starting from the Rayleigh-Sommerfeld diffraction integral,this paper studies the spectral behavior in Young's experiment illuminated by nonparaxial partially coherent light and compares with the paraxial case,where the influence of nonparaxiality of partially coherent light on the spectral shifts and spectral switches is stressed.It is shown that there is a spectral shift in the nonparaxial case relative to the paraxial one and the critical position changes,at which the spectral switch occurs.The ratio of the waist width to the central wavelength w 0 /λ 0 and relative spatial correlation length affect the spectral difference.The smaller w 0 /λ 0 is,the larger the difference between the nonparaxial and paraxial results appears.The effect of relative spatial correlation length is relatively small.展开更多
This paper presents a method to measure the in-plane displacement fields of curved surface bymoire interferometry of partial coherent light.The method has the following advantages:simple opticalsystem,no requirement o...This paper presents a method to measure the in-plane displacement fields of curved surface bymoire interferometry of partial coherent light.The method has the following advantages:simple opticalsystem,no requirement on vibration isolation,high sensitivity,large measuring range,high contrast of interference fringes and availability to in-situ structural testing.The present paper also gives theoretical analysis ofthe method and the formulas of light intensity and displacement field,and introduces a replication techniqueto form a high frequency reflectance grating on the curved surface.The experiments achieved the measurementof the surface displacement field of a cylindrical shell—the simultaneous circumferential,axial and 45°displacement fields.The torsional test data for surface displacement of a circular bar agree well with thetheoretical result.展开更多
We present a simple description of classical and quantum light propagating through homogeneous conducting linear media. With the choice of Coulomb gauge, we demonstrate that this description can be performed in terms ...We present a simple description of classical and quantum light propagating through homogeneous conducting linear media. With the choice of Coulomb gauge, we demonstrate that this description can be performed in terms of a damped harmonic oscillator which is governed by the Caldirola-Kanai Hamiltonian. By using the dynamical invariant method and the Fock states representation we solve the time-dependent Schr<span style="white-space:nowrap;">ö</span>dinger equation associated with this Hamiltonian and write its solutions in terms of a special solution of the Milne-Pinney equation. We also construct coherent states for the quantized light and show that they are equivalent to the well-known squeezed states. Finally, we evaluate some important properties of the quantized light such as expectation values of the amplitude and momentum of each mode, their variances and the respective uncertainty principle.展开更多
The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which re...The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which requires questionable supplements (dark matter, MOND, etc.). The Impulsive Stimulated Raman Scattering (ISRS) redshifts gradually light pulses which cross excited atomic hydrogen H*, so that the redshift is a measure of the column density of H*. Thus, the distance of the hot stars, surrounded by much H*, is exaggerated by the use of Hubble’s law. Local exaggerated distances create voids in the maps of galaxies which become spongy. The interpretation of spectra of quasars, the periodicity of galaxy redshifts introduce an experimental “Karlsson’s constant” exactly computed by ISRS. The need for dark matter comes from the exaggeration of the distance, therefore the size of galaxies. Without dark matter, celestial mechanics provides a reliable distance of spiral galaxies. Coherence also introduces superradiance and mode competition that explain that only the limbs of Stromgren spheres are visible as circles maybe punctuated by an even number of dots: Too numerous, the figures assigned to gravitational lenses can be such limbs. The coincidence of the ignition of the rings of SNR1987A with the extinction of the star is due to a multiphoton coherent scattering of star light, which amplifies the superradiant emission of the rings. A blueshift of microwaves crossing H* resulting, between 10 and 15 AU, of the expansion of solar wind, explains the “anomalous acceleration” of Pioneer probes. All is obtained without any change in theories of standard spectroscopy.展开更多
In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changin...In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.展开更多
On the one hand,existing measurement device independent quantum key distribution(MDI-QKD)protocols have usually adopted single photon source(SPS)and weak coherent photon(WCP),however,these protocols have suffered from...On the one hand,existing measurement device independent quantum key distribution(MDI-QKD)protocols have usually adopted single photon source(SPS)and weak coherent photon(WCP),however,these protocols have suffered from multi-photon problem brought from photon splitter number attacks.On the other hand,the orbital angular momentum(OAM)-MDI-QKD protocol does not need to compare and adjust the reference frame,solving the dependency of the base in the MDI-QKD protocol.Given that,we propose the OAM-MDI-QKD protocol based on the parametric light sources which mainly include single-photon-added-coherent(SPACS)and heralded single-photon sources(HSPS).Due to the stability of OAM and the participation of parametric light sources,the performance of MDI-QKD protocol gradually approaches the ideal situation.Numerical simulation shows that compared with WCP scheme,HSPS and SPACS schemes have increased the maximum secure transmission distance by 30 km and 40 km respectively.展开更多
This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator streng...This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator strength and binding energy of exciton. First, we investigate the variations in oscillator strength of exciton due to different quantum well size. Second, exciton binding energy level shift due to size of quantum well is investigated. According to this analysis, we have developed a new method for tuning slow light device bandwidth center frequency and slow down factor. Analysis and simulation of a basic GaAs/AlGaAs quantum wells optical slow light device based on excitonic population oscillation shows that size of quantum wells could tune both of the frequency properties and slow down factor of an optical slow light device. In our simulation with 34 quantum wells each with the width of 60?, we have received the slow down factor of more than 60,000. These achievements are useful in optical nonlinearity enhancements, all-optical signal processing applications and optical communications.展开更多
In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters ...In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters of slow light device and a method is presented for setting the output specifications of this kind of devices. In this paper, we deal with changing the size of quantum dot to find the ideal size. The simulation results indicate that as the size of quantum dot changes properly (with reducing more than 50 percent of quantum dots both radius and height), then the slope of diagram of the real part of refractive index increases significantly so that the Slow Down Factor (SDF) predicted to be18 times greater. Analysis and simulations based on cylinderical quantum dots structure slow light devices based on exitonic cpo.展开更多
For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered product(IW...For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered product(IWOP) of operators we find that it is a kind of one- and two-mode combinatorial squeezed state. Its application in evaluating the quantum fluctuation of photon number reveals: the stronger the squeezing is, the larger a fluctuation appears. The second-order degree of coherence of SCL is also deduced which shows that SCL is classic. The new thermal vacuum state also helps to derive the Wigner function of SCL.展开更多
文摘We demonstrate a high-speed swept-source optical coherence tomography (SS-OCT) system, which is based on a high-speed swept light source and a Mach-Zehnder interferometer with a high-speed photodetector. The light source is an external-cavity laser tuned by a KTN electro-optic deflector, which exhibits a very fast response and large deflection. The scanning wavelength range is almost 80 nm up to 200 kHz with a ±400-V deflector driving voltage. The system acquires 1 mm × 1 mm images consisting of 200 × 200 pixels within few milliseconds. We present preliminary SS-OCT images of an in-vitro human nail and an in-vivo finger pad.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921603)the National Natural Science Foundation of China(Grant Nos.11374126,11347137,11404336,and 11204103)+1 种基金the China Postdoctoral Science Foundation(Grant No.2013T60317)the National Fund for Fostering Talents of Basic Science,China(Grant No.J1103202)
文摘We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid.The essence of this multiple frequency conversion is four-wave mixing based on stored atomic spin coherence.Through electromagnetically induced transparency,an input probe pulse is stored into atomic spin coherence by modulating the intensity of the control field.By using two different control fields to interact with the coherently prepared medium,the stored atomic spin coherence can be transformed into three different information channels.Multiple frequency conversion is implemented efficiently by manipulating the spectra of the control fields to scatter atomic spin coherence.This multiple frequency conversion is expected to have potential applications in information processing and communication network.
文摘The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theoretical model, the effects of grain height, its density, the band width and spectral distribution of the line profile (Gaussian and Lorentzian) illuminating a rough surface on the visibility of speckle pattern are investigated. An experimental setup was constructed to study the effect of surface roughness and coherence of the illuminating light beam on the contrast of speckle pattern. The general behavior of the experimental results, which agree with published data, is compatible with the new theoretical model.
基金suported by the National Natural Science Foundation of China (Grant No 10574097)the Outstanding Young Researcher Foundation of Sichuan Province,China (Grant No 03ZQ026-061)+1 种基金the Applied and Basic Research Foundation of Sichuan Province,China (Grant No 05J Y029-102)the Natural Science Foundation of Yibin University,China (Grant No 2008B04)
文摘Starting from the Rayleigh-Sommerfeld diffraction integral,this paper studies the spectral behavior in Young's experiment illuminated by nonparaxial partially coherent light and compares with the paraxial case,where the influence of nonparaxiality of partially coherent light on the spectral shifts and spectral switches is stressed.It is shown that there is a spectral shift in the nonparaxial case relative to the paraxial one and the critical position changes,at which the spectral switch occurs.The ratio of the waist width to the central wavelength w 0 /λ 0 and relative spatial correlation length affect the spectral difference.The smaller w 0 /λ 0 is,the larger the difference between the nonparaxial and paraxial results appears.The effect of relative spatial correlation length is relatively small.
基金The project supported by National Natural Science Foundation of China.
文摘This paper presents a method to measure the in-plane displacement fields of curved surface bymoire interferometry of partial coherent light.The method has the following advantages:simple opticalsystem,no requirement on vibration isolation,high sensitivity,large measuring range,high contrast of interference fringes and availability to in-situ structural testing.The present paper also gives theoretical analysis ofthe method and the formulas of light intensity and displacement field,and introduces a replication techniqueto form a high frequency reflectance grating on the curved surface.The experiments achieved the measurementof the surface displacement field of a cylindrical shell—the simultaneous circumferential,axial and 45°displacement fields.The torsional test data for surface displacement of a circular bar agree well with thetheoretical result.
文摘We present a simple description of classical and quantum light propagating through homogeneous conducting linear media. With the choice of Coulomb gauge, we demonstrate that this description can be performed in terms of a damped harmonic oscillator which is governed by the Caldirola-Kanai Hamiltonian. By using the dynamical invariant method and the Fock states representation we solve the time-dependent Schr<span style="white-space:nowrap;">ö</span>dinger equation associated with this Hamiltonian and write its solutions in terms of a special solution of the Milne-Pinney equation. We also construct coherent states for the quantized light and show that they are equivalent to the well-known squeezed states. Finally, we evaluate some important properties of the quantized light such as expectation values of the amplitude and momentum of each mode, their variances and the respective uncertainty principle.
文摘The coherence of the interaction of light with a collisionless gas (Einstein 1917) founds the theory of gas lasers. It is, for the understanding of universe, a simpler and more powerful tool than the big bang which requires questionable supplements (dark matter, MOND, etc.). The Impulsive Stimulated Raman Scattering (ISRS) redshifts gradually light pulses which cross excited atomic hydrogen H*, so that the redshift is a measure of the column density of H*. Thus, the distance of the hot stars, surrounded by much H*, is exaggerated by the use of Hubble’s law. Local exaggerated distances create voids in the maps of galaxies which become spongy. The interpretation of spectra of quasars, the periodicity of galaxy redshifts introduce an experimental “Karlsson’s constant” exactly computed by ISRS. The need for dark matter comes from the exaggeration of the distance, therefore the size of galaxies. Without dark matter, celestial mechanics provides a reliable distance of spiral galaxies. Coherence also introduces superradiance and mode competition that explain that only the limbs of Stromgren spheres are visible as circles maybe punctuated by an even number of dots: Too numerous, the figures assigned to gravitational lenses can be such limbs. The coincidence of the ignition of the rings of SNR1987A with the extinction of the star is due to a multiphoton coherent scattering of star light, which amplifies the superradiant emission of the rings. A blueshift of microwaves crossing H* resulting, between 10 and 15 AU, of the expansion of solar wind, explains the “anomalous acceleration” of Pioneer probes. All is obtained without any change in theories of standard spectroscopy.
文摘In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.
基金Hong Lai has been supported by the National Natural Science Foundation of China(No.61702427)the Chongqing innovation project(No.cx2018076)+1 种基金the Fundamental Research Funds for the Central Universities(XDJK2018C048)the financial support in part by the 1000-Plan of Chongqing by Southwest University(No.SWU116007)。
文摘On the one hand,existing measurement device independent quantum key distribution(MDI-QKD)protocols have usually adopted single photon source(SPS)and weak coherent photon(WCP),however,these protocols have suffered from multi-photon problem brought from photon splitter number attacks.On the other hand,the orbital angular momentum(OAM)-MDI-QKD protocol does not need to compare and adjust the reference frame,solving the dependency of the base in the MDI-QKD protocol.Given that,we propose the OAM-MDI-QKD protocol based on the parametric light sources which mainly include single-photon-added-coherent(SPACS)and heralded single-photon sources(HSPS).Due to the stability of OAM and the participation of parametric light sources,the performance of MDI-QKD protocol gradually approaches the ideal situation.Numerical simulation shows that compared with WCP scheme,HSPS and SPACS schemes have increased the maximum secure transmission distance by 30 km and 40 km respectively.
文摘This paper investigates the effects of quantum well size changes on center frequency and slow down factor of an slow light device. In this way, we consider the quantum well size alteration effects on oscillator strength and binding energy of exciton. First, we investigate the variations in oscillator strength of exciton due to different quantum well size. Second, exciton binding energy level shift due to size of quantum well is investigated. According to this analysis, we have developed a new method for tuning slow light device bandwidth center frequency and slow down factor. Analysis and simulation of a basic GaAs/AlGaAs quantum wells optical slow light device based on excitonic population oscillation shows that size of quantum wells could tune both of the frequency properties and slow down factor of an optical slow light device. In our simulation with 34 quantum wells each with the width of 60?, we have received the slow down factor of more than 60,000. These achievements are useful in optical nonlinearity enhancements, all-optical signal processing applications and optical communications.
文摘In this paper we simulate and analyze a sample of slow light semiconducting device with quantum dot structure based on coherent population oscillation (CPO). The simulation is conducted to enhance the main parameters of slow light device and a method is presented for setting the output specifications of this kind of devices. In this paper, we deal with changing the size of quantum dot to find the ideal size. The simulation results indicate that as the size of quantum dot changes properly (with reducing more than 50 percent of quantum dots both radius and height), then the slope of diagram of the real part of refractive index increases significantly so that the Slow Down Factor (SDF) predicted to be18 times greater. Analysis and simulations based on cylinderical quantum dots structure slow light devices based on exitonic cpo.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.1117511311447202and 11574295)
文摘For the density operator(mixed state) describing squeezed chaotic light(SCL) we search for its thermal vacuum state(a pure state) in the real-fictitious space. Using the method of integration within ordered product(IWOP) of operators we find that it is a kind of one- and two-mode combinatorial squeezed state. Its application in evaluating the quantum fluctuation of photon number reveals: the stronger the squeezing is, the larger a fluctuation appears. The second-order degree of coherence of SCL is also deduced which shows that SCL is classic. The new thermal vacuum state also helps to derive the Wigner function of SCL.