84,908 research outputs found
Experimental investigation of linear-optics-based quantum target detection
The development of new techniques to improve measurements is crucial for all
sciences. By employing quantum systems as sensors to probe some physical
property of interest allows the application of quantum resources, such as
coherent superpositions and quantum correlations, to increase measurement
precision. Here we experimentally investigate a scheme for quantum target
detection based on linear optical measurment devices, when the object is
immersed in unpolarized background light. By comparing the quantum
(polarization-entangled photon pairs) and the classical (separable polarization
states), we found that the quantum strategy provides us an improvement over the
classical one in our experiment when the signal to noise ratio is greater than
1/40, or about 16dB of noise. This is in constrast to quantum target detection
considering non-linear optical detection schemes, which have shown resilience
to extreme amounts of noise. A theoretical model is developed which shows that,
in this linear-optics context, the quantum strategy suffers from the
contribution of multiple background photons. This effect does not appear in our
classical scheme. By improving the two-photon detection electronics, it should
be possible to achieve a polarization-based quantum advantage for a signal to
noise ratio that is close to 1/400 for current technology.Comment: comments are welcome, submitted to PR
Optical Hyperlens: Far-field imaging beyond the diffraction limit
We propose an approach to far-field optical imaging beyond the diffraction
limit. The proposed system allows image magnification, is robust with respect
to material losses and can be fabricated by adapting existing metamaterial
technologies in a cylindrical geometry
Continuous-wave phase-sensitive parametric image amplification
We study experimentally parametric amplification in the continuous regime
using a transverse-degenerate type-II Optical Parametric Oscillator operated
below threshold. We demonstrate that this device is able to amplify either in
the phase insensitive or phase sensitive way first a single mode beam, then a
multimode image. Furthermore the total intensities of the amplified image
projected on the signal and idler polarizations are shown to be correlated at
the quantum level.Comment: 14 pages, 7 figures, submitted to Journal of Modern Optics, Special
Issue on Quantum Imagin
Optical imaging techniques in microfluidics and their applications
Microfluidic devices have undergone rapid development in recent years and provide a lab-on-a-chip solution for many biomedical and chemical applications. Optical imaging techniques are essential in microfluidics for observing and extracting information from biological or chemical samples. Traditionally, imaging in microfluidics is achieved by bench-top conventional microscopes or other bulky imaging systems. More recently, many novel compact microscopic techniques have been developed to provide a low-cost and portable solution. In this review, we provide an overview of optical imaging techniques used in microfluidics followed with their applications. We first discuss bulky imaging systems including microscopes and interferometer-based techniques, then we focus on compact imaging systems that can be better integrated with microfluidic devices, including digital in-line holography and scanning-based imaging techniques. The applications in biomedicine or chemistry are also discussed along with the specific imaging techniques
Quantum Theory of Superresolution for Two Incoherent Optical Point Sources
Rayleigh's criterion for resolving two incoherent point sources has been the
most influential measure of optical imaging resolution for over a century. In
the context of statistical image processing, violation of the criterion is
especially detrimental to the estimation of the separation between the sources,
and modern farfield superresolution techniques rely on suppressing the emission
of close sources to enhance the localization precision. Using quantum optics,
quantum metrology, and statistical analysis, here we show that, even if two
close incoherent sources emit simultaneously, measurements with linear optics
and photon counting can estimate their separation from the far field almost as
precisely as conventional methods do for isolated sources, rendering Rayleigh's
criterion irrelevant to the problem. Our results demonstrate that
superresolution can be achieved not only for fluorophores but also for stars.Comment: 18 pages, 11 figures. v1: First draft. v2: Improved the presentation
and added a section on the issues of unknown centroid and misalignment. v3:
published in Physical Review
Multispectral linear array multiband selection device
An apparatus for detecting multiple spectral bands, individually or concurrently, using linear detector arrays is described. The system employs a beamsplitter to divide the optical source into two or more optical beams which are directed at the linear detector arrays. Filter trays are positioned in the focal planes of the optical beams so that the beams pass through the filter trays prior to impinging upon the detector arrays. Multiple filters are placed on the filter trays. Linear actuators positioned adjacent the filter trays translate the trays across the focal planes of the optical beams so that individual filters are positioned in the path of beams such that those frequencies of the beams that fall within the spectral ranges of the individual bandpass filter through which it passes may be detected by the detector arrays for further examination and analysis
- …