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Publications (66)
Computational imaging allows image formation with single-pixel detectors that have no spatial resolution. It has wide-ranging potential applications in fields ranging from biomedical imaging to remote sensing. However, the practical applications of computational imaging are limited due to the high sampling ratio, weak robustness, and low resolution...
Computational imaging enables spatial information retrieval of objects with the use of single-pixel detectors. By combining measurements and computational methods, it is possible to reconstruct images in a variety of situations that are challenging or impossible with traditional multi-pixel cameras. However, these systems typically suffer from sign...
High-resolution optical imaging through or within thick scattering media is a long sought after yet unreached goal. In the past decade, the thriving technique developments in wavefront measurement and manipulation do not significantly push the boundary forward. The optical diffusion limit is still a ceiling. In this work, we propose that a scatteri...
Imaging objects hidden behind an opaque shelter provides a crucial advantage when physically going around the obstacle is impossible or dangerous. Previous methods have demonstrated that is possible to reconstruct the image of a target hidden from view. However, these methods enable the reconstruction by using the reflected light from a wall which...
Imaging through disordered media is an challenging problem. When there is plenty of photon budget, the imaging recovery could be realized by exploiting the input–output “transmission matrix (TM)” which is considered as mesoscopic property of the media. However, when the photon budget is extremely limited, this method is no longer useful. The inevit...
We propose and validate a deep learning based algorithm for recovering images from their photon-limited samples. The method can be applied to complicated images and is able to retain most of the details.
We experimentally reconstruct high-quality images through dynamic media using as little as ∼0.4 photons per pixel by proposed scalable method, which provides guidance on the real-time photon-limited time-varying scattering imaging applications such as in vivo bioimaging.
Single-pixel imaging (SPI) can reduce the cost and have the potential of being competent for some challenging tasks. However, for a SPI system, acquiring detailed information from a complex scene for complex vision task is a measurements-consuming process, by which low efficiency resulted is one of the important obstructions of SPI for practical ap...
When light travels through scattering media, speckles (spatially random distribution of fluctuated intensities) are formed due to the interference of light travelling along different optical paths, preventing the perception of structure, absolute location and dimension of a target within or on the other side of the medium. Currently, the prevailing...
Photon-limited imaging technique is desired in tasks of capturing and reconstructing images by detecting a small number of photons. However, it is still a challenge to achieve high photon-efficiency. Here, we propose a novel photon-limited imaging technique that explores the consistency of photon detection probability in a single pulse and light in...
Under photon-limited detection which is limited by the low-light illumination and short detection time, off-the-shelf classification methods based on clear imaging of the object cannot achieve considerable classification accuracy. To solve this problem, we propose a non-imaging classification method based on single-pixel imaging system. With low-in...
Discrete cosine single-pixel imaging with binary illumination can fastly reconstruct a scene where area of the salient object can be detected rapidly and accurately even in the case of undersampling, utilizing deep learning model.
A proof-of-principle experiment was carried out to demonstrate that under a photon- limited detection condition, an imaging-free image-based object classification could be realized via simple machine-learning algorithm with simulated training data.
Imaging under ultra-weak light conditions is affected by Poisson noise heavily. The problem becomes worse if a scattering media is present in the optical path. Speckle patterns detected under ultra-weak light condition carry very little information which makes it difficult to reconstruct the image. Off-the-shelf methods are no longer available in t...
Under complex scattering conditions, it is very difficult to capture clear object images hidden behind the media by modelling the inverse problem. With regard to dynamic scattering media, the challenge increases. For solving the inverse problem, we propose a new class-specific image reconstruction algorithm. The method based on deep learning classi...
Photon-limited imaging has significant application under extreme environments, in which the photon efficiency is an important parameter. In this paper, we investigate the photon efficiency of computational ghost imaging with single-photon detection. By exploiting the Poisson statistical characteristics of single-photon counting, the relationships b...
With one single photon camera (SPC), imaging under ultra weak-lighting conditions may have wide-ranging applications ranging from remote sensing to night vision, but it may seriously suffer from the problem of under-sampled inherent in SPC detection. Some approaches have been proposed to solve the under-sampled problem by detecting the objects many...
Single-pixel imaging has emerged over recent years as a novel imaging technique, which has significant application prospects. In this paper, we propose and experimentally demonstrate a scheme that can achieve single-pixel non-imaging object recognition by acquiring the Fourier spectrum. In an experiment, a four-step phase-shifting sinusoid illumina...
Conventional imaging at low light levels requires hundreds of detected photons per pixel to suppress the Poisson noise for accurate reflectivity inference. We propose a high-efficiency photon-limited imaging technique, called fast first-photon ghost imaging, which recovers the image by conditional averaging of the reference patterns selected by the...
Conventional imaging at low light level requires hundreds of detected photons per pixel to suppress the Poisson noise for accurate reflectivity inference. In this letter, we propose a high-efficiency photon-limited imaging technique, called first-photon ghost imaging, which recovers image from the first-photon detection by exploiting the physics of...
We proposed a method for polarization ghost imaging based on single photon counting. With the time-correlated single-photon-counting technique, we can construct photon time distribution histograms and select a distance gate to accurately estimate the light intensity. Experiments are performed to realize discrimination of the object from the backgro...
The quality of thermal light ghost imaging could be degraded by undersampling noise. This kind of noise is generated because of finite sampling, which could reduce the signal-to-noise ratio (SNR) of ghost imaging and submerge object information. In order to reduce the undersampling noise, we propose a thermal light ghost imaging scheme based on the...
Ghost imaging is a transverse imaging technique that allows an object to be reconstructed using the correlation between a pair of light fields. As known, in ghost imaging configurations, a large number of realizations are usually required for reconstruction of the objects. To reduce the number of realizations, Chen et al. [Opt. Lett. 38, 546–548 (2...
In this paper, we proposed a pseudo antibunching effect on one single photon detector. Though this pseudo antibunching effect is not a sign of the non classical properties of the light field as the antibunching effect. It will give some intresting properties to the photon statistics of the related fields, such as the anticorrelation of photon numbe...
Imaging at low light levels has drawn much attention. In this paper, a method is experimentally demonstrated to realize computational imaging under weak illumination conditions. In our experiment, only one single-photon detector was used to capture the photons. With the time-correlated single-photon-counting technique, photons at a quite low level...
We propose the polarization difference ghost imaging method and experimentally demonstrate that polarization properties can provide additional information in conventional ghost imaging for object discrimination with contrast enhancement. In our experiment, two kinds of visually similar objects with different polarization properties can be separated...
The intensity fluctuation correlation of pseudo-thermal light can be utilized
to realize binocular parallax stereo imaging (BPSI). With the help of
correlation matching algorithm, the matching precision of feature points can
reach one pixel authentically. The implementations of the proposed BPSI system
with real objects were demonstrated in detail....
We experimentally demonstrate a three-dimensional (3D) ghost imaging method based on period diffraction correlation imaging. Compared with conventional ghost imaging, our method can easily retrieve the images of different focal planes. Due to the correlation between the disturbed object beam and the reference beams which do not pass through any sca...
The resolution of classical imaging is limited by the Rayleigh diffraction limit, whereas ghost imaging can overcome this diffraction limit and enhance the resolution. In this paper, we propose a super-resolution thermal ghost imaging scheme based on deconvolution, which can further improve the imaging resolution. Because the traditional thermal gh...
We experimentally demonstrate that polarization difference ghost imaging can provide the visibility and contrast enhancement, especially when the target is under predominately reflecting objects, complex background or turbid media. It facilitates the practical applications of ghost imaging.
We demonstrate a series of experiments on imaging through both stationary aberrating media and moving aberrating media by computational ghost imaging (CGI). An incoherent LED light source is used instead of the common pseudothermal light source (laser light passing through a rotating ground glass). A digital micromirror device is used as a simple s...
In practical thermal light ghost imaging, the nonuniform intensity distribution of the thermal light applied causes distortion of the retrieved image. We propose uniformly weighted arithmetics, including uniformly weighted ghost imaging and uniformly weighted differential ghost imaging (UWDGI), to improve the imaging quality of ghost imaging with n...
In Periodic diffraction correlation imaging (PDCI), the images of several objects located in different spatial positions can be integrated into one image following certain rules, which is named shape merging. In this paper, we proposed and demonstrated this new technique. It can be realized without SLM or beam-splitter. And this effect can find nov...
We demonstrate an experiment of imaging through a scattering layer based on periodic diffraction correlation imaging. No matter the scattering layer is immobile or vibratory, multiple images can be periodically obtained in the uncovered zones by periodic diffraction correlation imaging. The implementation of this experiment is quite simple and low-...
We use a chaotic laser, instead of thermal light, as the light source in temporal ghost imaging. This laser is generated by employing an external optical feedback. The imaging magnification is varied by adjusting the group-delay dispersion parameters of the fibers. The temporal ghost imaging result is the convolution between the transmission functi...
We demonstrate an experiment of imaging through strongly scattering layers based on period diffraction correlation imaging. The implementation of this experiment is quite simple. This technique could find applications in imaging biological tissues.
Conventional ghost imaging can only obtain two dimensional image because it only uses spatial correlation
characteristics of light source. We describe a three dimensional arrangement using only a single-pixel detector
based on computational ghost imaging. The three dimensional image of the object can be divided into gray-scale
image and digital ele...
We demonstrate the periodic diffraction correlation imaging (PDCI) of a reflective object using only one array detector to achieve simpler setups of ghost imaging: no beam-splitter is needed, and only one detector is utilized. Multiple reference beams with a same pattern of the signal beam are generated in the PDCI, which makes PDCI realize high-or...
The performances of ideal high-order thermal ghost imaging, including conventional high-order ghost imaging, background-subtracted high-order ghost imaging (BSGI), and intensity fluctuation high-order ghost imaging (IFGI), are compared in this paper. The detailed quality analyses of the three high-order ghost imaging algorithms are demonstrated. Th...
We theoretically investigate an all-optical isolator under arbitrary linearly polarized fundamental wave (FW) input in an optical superlattice (OSL). The scheme is based on simultaneously phase matching the first-order Type I (oo-e) quasi-phase-matching (QPM) second-harmonic generation (SHG) process and higher-order Type 0 (ee-e) QPM SHG process in...
In this paper, we theoretically propose a new method to generate and tune the optical orbital angular momentum. A focused Gaussian beam passing through an optical superlattice under the electro-optic effect carries orbital angular momentum (OAM). This kind of OAM arises from the curl of the polarization. By adjusting the external electric field, th...
In this chapter, we have reviewed essential applications by use of polarization coupling in periodically poled lithium niobate during the past five years. Because of the outstanding properties of PPLN, we believe that PPLN will remain to be an important contemporary realm of research.
We have theorized that a photonic band gap can be induced in a submicron periodically poled LiNbO3 (SPPLN) with a uniform electrical field applied along the Y axis of the structure. The width of the band gap can be modulated by the intensity of the Y-directional electrical field. Moreover, for such a periodical structure with a duty cycle other tha...
We investigated the properties of single-pass second-harmonic generation of CW 532 nm radiation with a single frequency Nd:YAG laser by QPM in Mg:SLT. SHG upper limit can be increased by shifting the focus position.
We demonstrate a quasi-periodic structure exhibiting multiple photonic band gaps (PBGs) based on sub-micron-period poled lithium niobate (LN). The structure consists of two building blocks, each containing a pair of antiparallel poled domains, arranged as a Fibonacci sequence. The gap wavelengths are analyzed with the Fibonacci sequence parameters...
We propose a flat-top bandpass Solc-type filter in a periodically poled lithium niobate crystal. Our study reveals several critical electric fields at which the transmission spectrum surprisingly evolves into a flat-top one, which is a new method for obtaining a flat-top wavelength filter. Because the flat-top passband width can be controlled by th...
In this letter, we propose a simple configuration capable of rotating a linear polarization state of light by a certain angle with high precision for a series of wavelengths. This is achieved in a compact one-chip integration of periodically poled lithium niobate (PPLN) by modulating the external electric field. During the experiment, the rotation...
In this paper, we review current research on the applications of periodically poled lithium niobate (PPLN) by use of polarization coupling in our and other research groups. Tun-able wavelength Solc-type filter, polarization controller and electro-optical switch based on PPLN are presented, which show potential applications in optical communications...
Based on the spectrum waveform similarity (SWS) rule we discovered in periodically poled lithium niobate (PPLN), a compact tunable flat-top bandpass filter is proposed theoretically, from which the bandwidth of the flat-top waveform can be obtained. For practical application, tunable flat-top filter can be easily achieved by selecting appropriate e...
In this paper, we present our researches on the applications of periodically poled lithium niobate (PPLN) in optical communications. Tunable wavelength converter and filter are investigated based on PPLN with unique features which show potential applications in next generation all-optical networks.
A tunable multi-wavelength filter can be realized in periodically poled LiNbO3 by using a local-temperature-control technique. In this paper, a tunable single-wavelength and double-wavelength filter of this kind is experimentally demonstrated. In our experiment, the output transmissivity peaks of the filter can be tuned to any wavelengths by proper...
We propose an ultrafast pulse shaping method by modulating the pulse phase and amplitude by the electro-optic effect and Bragg diffraction in the aperiodically optical superlattice. Linear-chirped periodically poled lithium niobate is used. The input pulse can be shaped, for example, by compressing it through the extraordinary refractive index chan...
We demonstrate a tunable Šolc-type filter in periodically poled lithium niobate by UV-light illumination in this paper. Due to the photovoltaic effect, a Šolc-type filter in PPLN can be formed without applying an external electric field. Through this mechanism, a tunable wavelength filter by UV-light illumination is realized. A wavelength shift as...
We report a non-field-applied Solc-type filter constructed by a periodically poled lithium niobate (PPLN). By comparing two types of PPLN Solc filter setup, both theoretically and experimentally, we have proved that without external field applied, it is the photovoltaic effect that introduces pass peak in the PPLN band filter.
We demonstrate an electro-optič Solc-type wavelength filter in periodically poled lithium niobate (PPLN) Solc-type transmission spectrum is observed experimentally in a PPLN with four periods from 20.2 µm to 20.8 µm. Modulation of transmission power of the filter can be realized by applying electric fields along Y -axis of PPLN. It is observed that...
In this paper, a tunable narrowband spectral filter in periodically poled lithium niobate (PPLN) by temperature is experimentally demonstrated. We observe a shift of transmission spectrum of PPLN S Solc-type filter when the tem-perature is modified. The tuning rate is measured to be)0.422 nm/°C, which is in agreement with calculation results of the...
We demonstrate an electro-optic Solc-type wavelength filter in periodically poled lithium niobate (PPLN). A Solc-type transmission spectrum is observed experimentally in PPLN with four periods from 20.2 to 20.8 µ m . Modulation of the transmission power of the filter is realized by application of electric fields along the Y axis of the PPLN. It is...
We propose a method to control the polarization of light by the electro-optic effect in periodically poled lithium niobate. A single integrated chip of Z-cut lithium niobate having two sections is used. The first section is not periodically poled, whereas the second section is. With an electric field applied along the Z axis of the first section an...
The first observation is reported of a Solc-like filter in periodically poled lithium niobate, a device with outstanding nonlinear optical properties. Using the so called quasiphase-matching (QPM) technique, which has many advantages compared to conventional birefringence phase matching, enhancement of conversion efficiency was obtained in optical...
Polarization controller (PC) for optical fiber is a major area of study in the general field of coherent-optical communication systems. In communication systems based on single-mode fiber, the states of polarization in fiber vary randomly due to temperature variations and mechanical perturbations along the fiber. These polarization changes can have...
Spurred by exploding demand for transmission capacity, several techniques have been developed in dense wavelength division multiplexing(DWDM) systems for packing as many channel as possible into fibre-amplifier active regions. An interleave filter, which separates DWDM signal channels with equal spacing into two groups with twice the spacing, has r...
In common electro-optic modulators (EO), the inherent velocity mismatching between the optical wave and microwave is the major factor hampering efficient modulation. In this paper, we briefly compare periodically reversed electrode and domain reversal scheme (two ways of achieving quasi-velocity- matching), then we give the design principle of the...
