We propose and demonstrate a new correlation imaging method using a periodic light source array. The image of the object is reconstructed by exploiting the correlation between the total intensity of the beam interacting with the object and the precomputed intensity distribution patterns of the light source. The implementation of this experiment is quite simple and low-cost without the need for a beam splitter or spatial light modulator. Due to its single-pixel detection configuration, it should have great potential in many imaging applications.
Proc. SPIE. 9795, Selected Papers of the Photoelectronic Technology Committee Conferences held June–July 2015
KEYWORDS: Signal to noise ratio, Infrared sensors, Infrared imaging, Detection and tracking algorithms, Imaging systems, Sensors, Image retrieval, Digital micromirror devices, Spatial resolution, Signal detection
Traditional imaging are mostly based on the principle of lens imaging which is simple but the imaging result is heavily dependent on the quality of detector. It is usual to increase the detector array density or reduce the size of pixels to improve the imaging resolution, especially for infrared imaging. It will decrease the light flux causing the noise enhance relatively and add the cost on the contrary. Besides, there is a novel imaging technology called ghost imaging. We present a new infrared imaging method named computational ghost imaging only using a bucket detector without spatial resolution, which avoiding the allocation of flux on the pixel dimension as well as reducing the cost.
Single-photon detectors are of great importance in spectroscopy, laser ranging, astronomy and wherever weak light detection is required, so a precise knowledge of their quantum efficiency is essential, but their calibration is by no means trivial. Traditional methods need a black body radiation source or a highly attenuated laser beam as a reference standard, or an already calibrated reference detector. It is well known that absolute measurement of the quantum efficiency, absolute in the sense that the calibration is independent of any radiometric standard or the properties of another detector, can be performed using entangled twin photons generated in optical spontaneous parametric down-conversion together with a reference detector. We have performed the first proof-of-principle experiment to determine the quantum efficiency by which no second detector or reference standard is required. This absolute self-calibration method is also based on the time correlation of photons emitted in parametric down-conversion, but with the introduction of a suitable time delay between the arrival times of the twin photons. Furthermore, we describe a scheme for absolute self-calibration of the quantum efficiency at different wavelengths by means of a pulsed source of nondegenerate down-converted photons. This method should have even greater potential for applications.
We suggest here a two-point eavesdropping strategy aimed at a two nonorthogonal states protocol of quantum key distribution over a fiber-optic channel. When the single-photon sources and detectors of Alice, Bob and the two Eve are all ideal, the two-point attack can break the two nonorthogonal states protocol if the distance between Alice and Bob is longer than 30 km. However, Bennett's original multi-photon protocol is secure against both two-point and beam splitting attacks, though the protocol is realized with a weak pulsed source.
We present a new kind of quantum cryptography protocol based on Shamir's three-pass protocol of classical cryptography, which allows the transmission of qubits directly and secretly via the aid of an unjammable classical channel. In this protocol we implement the encryption and decryption transformations via rotations on the Poincare sphere of the photons polarization parameters. The key technique is that Bob's encryption rotation must be commutative with Alice s decryption rotation; this means that the axes of these two
rotations must be parallel. We also present a security analysis of the protocol under a man-in-the-middle attack.
We present a repeatable BB84 protocol for a hybrid quantum key distribution system based on the dual-velocity protocol and an error-correction scheme. This protocol is the first one that is immune to photon absorption, suitable for single-photon transmission and does not need any entanglement between photons.
Silicon avalanche photodiodes operated int he Geiger mode are capable of detecting single photons in the near infrared regime. We have designed and tested two types of quenching circuit, with a dead time of about 1 microsecond in the passive quenching mode and 60 ns in the active quenching mode. The performance of our detectors under various operating temperatures has been investigated, and measurements down to liquid nitrogen temperatures are reported for the first time.
We report a new type of optical parametric oscillator (OPO) cavity, i.e. a compound cavity OPO, and present its time dynamics based on a mathematical model. Both the numerical simulation and experimental results show that this type of cavity is superior in that its threshold is lower than that of a simple narrow-band cavity with dispersive elements, and its external efficiency is increased while its narrow linewidth remains nearly the same across the tunable range of the nonlinear crystals used.
We investigate the quantum fluctuations of the fields produced in sum- and difference- frequency generation from light initially in the squeezed state. Under certain conditions the output may also be squeezed.
We investigate the quantum statistics of the fields produced when squeezed light is used as input in certain three-wave and four-wave interactions such as second harmonic generation and degenerate four-wave mixing.