SPIE Photonics Europe最新文献

{"title":"Low-noise quantum frequency down-conversion of indistinguishable photons (Conference Presentation)","authors":"Benjamin Kambs, J. Kettler, M. Bock, J. Becker, C. Arend, M. Jetter, P. Michler, C. Becher","doi":"10.1117/12.2225932","DOIUrl":"https://doi.org/10.1117/12.2225932","url":null,"abstract":"Single-photon sources based on quantum dots have been shown to exhibit almost ideal properties such as high brightness and purity in terms of clear anti-bunching as well as high two-photon interference visibilities of the emitted photons, making them promising candidates for different quantum information applications such as quantum computing, quantum communication and quantum teleportation. However, as most single-photon sources also quantum dots typically emit light at wavelengths of electronic transitions within the visible or the near infrared range. In order to establish quantum networks with remote building blocks, low-loss single photons at telecom wavelengths are preferable, though. Despite recent progress on emitters of telecom-photons, the most efficient single-photon sources still work at shorter wavelengths. On that matter, quantum frequency down-conversion, being a nonlinear optical process, has been used in recent years to alter the wavelength of single photons to the telecom wavelength range while conserving their nonclassical properties. Characteristics such as lifetime, first-order coherence, anti-bunching and entanglement have been shown to be conserved or even improved due to background suppression during the conversion process, while the conservation of indistinguishability was yet to be shown. Here we present our experimental results on quantum frequency down-conversion of single photons emitted by an InAs/GaAs quantum dot at 903.6 nm following a pulsed excitation of a p-shell exciton at 884 nm. The emitted fluorescence photons are mixed with a strong pump-field at 2155 nm inside a periodically poled lithium niobate ridge waveguide and converted to 1557 nm. Common issues of a large background due to Raman-scattered pump-light photons spectrally overlapping with the converted single photons could largely be avoided, as the pump-wavelength was chosen to be fairly longer than the target wavelength. Additional narrowband spectral filtering at the telecom regime as a result of the small conversion bandwidth and using a high-performance fiber-Bragg-grating solely left the detector dark counts as the only noise source in our setup. Therefore, we could achieve conversion efficiencies of more than 20 %. In order to test the indistinguishability, sequentially emitted photons were fed into a Mach-Zehnder interferometer and spatially as well as temporally overlapped at the output beam splitter. Cross-correlation measurements between both output-ports of the beam splitter exhibit two-photon interference contrasts of more than 40 % prior to and after the down-conversion step. Accordingly, we demonstrate that the process of quantum frequency conversion preserves photon indistinguishability and can be used to establish a versatile source of indistinguishable single photons at the telecom C-Band. Furthermore our scheme allows for converting photons in a wavelength band from 900 nm to 910 nm to the same telecom target wavelength. This enables ","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127067959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of array photodetectors characteristics on the accuracy of the optical-electronic system with optical equisignal zone","authors":"V. Gusarov, A. Maraev, A. Timofeev, A. A. Klimov","doi":"10.1117/12.2227375","DOIUrl":"https://doi.org/10.1117/12.2227375","url":null,"abstract":"In this paper we attempt to assess the possibility of applying the array of photodetectors and digital information processing in positioning systems based on optical equisignal zone. The basic theoretical information about working principles of the system with equisignal zone and the formation of the base direction are listed. The influence on the accuracy of the positioning system some parameters such as the number and size of the array elements of the receiver, capacity analog-digital converter, aberrations of optical elements are researched. The possibility of registering the angular displacements (reversals) of the controlled object by using the developed system is shown.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"712 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125875109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Texel-based image classification with orthogonal bases","authors":"Erik Carbajal-Degante, R. Nava, Jimena Olveres, B. Escalante-Ramírez, J. Kybic","doi":"10.1117/12.2228694","DOIUrl":"https://doi.org/10.1117/12.2228694","url":null,"abstract":"Periodic variations in patterns within a group of pixels provide important information about the surface of interest and can be used to identify objects or regions. Hence, a proper analysis can be applied to extract particular features according to some specific image properties. Recently, texture analysis using orthogonal polynomials has gained attention since polynomials characterize the pseudo-periodic behavior of textures through the projection of the pattern of interest over a group of kernel functions. However, the maximum polynomial order is often linked to the size of the texture, which implies in many cases, a complex calculation and introduces instability in higher orders leading to computational errors. In this paper, we address this issue and explore a pre-processing stage to compute the optimal size of the window of analysis called “texel.” We propose Haralick-based metrics to find the main oscillation period, such that, it represents the fundamental texture and captures the minimum information, which is sufficient for classification tasks. This procedure avoids the computation of large polynomials and reduces substantially the feature space with small classification errors. Our proposal is also compared against different fixed-size windows. We also show similarities between full-image representations and the ones based on texels in terms of visual structures and feature vectors using two different orthogonal bases: Tchebichef and Hermite polynomials. Finally, we assess the performance of the proposal using well-known texture databases found in the literature.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126374234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulator of human visual perception","authors":"V. Bezzubik, N. Belashenkov","doi":"10.1117/12.2228176","DOIUrl":"https://doi.org/10.1117/12.2228176","url":null,"abstract":"Difference of Circs (DoC) model allowing to simulate the response of neurons – ganglion cells as a reaction to stimuli is represented and studied in relation with representation of receptive fields of human retina. According to this model the response of neurons is reduced to execution of simple arithmetic operations and the results of these calculations well correlate with experimental data in wide range of stimuli parameters. The simplicity of the model and reliability of reproducing of responses allow to propose the conception of a device which can simulate the signals generated by ganglion cells as a reaction to presented stimuli. The signals produced according to DoC model are considered as a result of primary processing of information received from receptors independently of their type and may be sent to higher levels of nervous system of living creatures for subsequent processing. Such device may be used as a prosthesis for disabled organ.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124909356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dating water with trace analysis at the quantum limit (Conference Presentation)","authors":"M. Oberthaler","doi":"10.1117/12.2228736","DOIUrl":"https://doi.org/10.1117/12.2228736","url":null,"abstract":"General dating schemes rely on the radioactive decay of elements. For dating of water the isotope 39Ar is very interesting since it is inert and has a halflife of 265 years, with which is matches the natural timescales of underground and deep ocean circulation. Applying atom optical techniques we could demonstrate that this very rare isotope, which is 15 orders of magnitude less abundant than the stable isotope can be detect one by one.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121824268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polychromatic see-through near-eye display design with two waveguides and a large field-of-view","authors":"Jianming Yang, P. Gerard, P. Twardowski, J. Fontaine","doi":"10.1117/12.2227383","DOIUrl":"https://doi.org/10.1117/12.2227383","url":null,"abstract":"We propose a new kind of waveguide near eye display (WGNED) with new in-coupling and propagation subsystems to vertically enlarge the field-of-view (FOV). Two waveguides are stacked up with a 0.1 mm air gap so that light can propagate inside the two waveguides independently. The light from a micro-display is coupled into the first waveguide by the in-coupling subsystem. Light propagates inside the first waveguide until reaching a cylindrical mirror at its edge. In the area near the mirror, the two waveguides are combined together. Then, the light is reflected by a cylindrical mirror and coupled to the second waveguide. The out-coupling from the second waveguide is realized either by a holographic optical element or cascaded micro mirrors. A cylindrical mirror allows most of the light coming out to reach the viewer’s eye. A two-lens subsystem with freeform surfaces is used as an in-coupling element to correct the aberrations. An advantage of our design is that the chief ray of each object field converges to the eye with an enlarged FOV in the vertical direction. The system has been simulated in mixed sequential and non-sequential mode in Zemax®. It can achieve a 20°×55° total FOV which is, to our knowledge, larger than the published WGNED designs.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131866652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The formation of zinc and copper oxides thin films for heterostructure solar cells","authors":"V. Afanasjev, G. Konoplev, D. Chigirev, N. Mukhin, E. Terukov, E. Terukova","doi":"10.1117/12.2227421","DOIUrl":"https://doi.org/10.1117/12.2227421","url":null,"abstract":"Optical and electrical properties (Haze spectra, carrier concentration, mobility, resistivity) of zinc oxide thin films deposited on glass substrates were studied by plasma treatment and by thermal annealing. Films of copper oxides on the glass and CuO/ZnO structures were formed by vacuum deposition of copper films followed by thermal annealing in air. Optical and structural properties of the CuO films and electrical properties of ZnO/CuO structures were investigated upon thermal treatment. It is shown that a photosensitive n-ZnO/p-CuO heterojunction may be formed by rapid (~1 min) thermal processing in air.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128316131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rear side gratings for silicon solar cells: efficiency enhancement finally demonstrated","authors":"B. Bläsi, N. Tucher, Johannes Eisenlohr, Benjamin G. Lee, J. Benick, H. Hauser, M. Hermle, J. Goldschmidt","doi":"10.1117/12.2228713","DOIUrl":"https://doi.org/10.1117/12.2228713","url":null,"abstract":"After more than 20 years of research on rear side gratings for light trapping in solar cells, we have been able to demonstrate enhanced efficiencies for crystalline silicon solar cells with two different grating concepts and solar cell architectures. In both cases planar front sides have been used. With hexagonal sphere gratings and the tunnel oxide passivated contact (TOPCon) concept, a grating induced Jsc increase of 1.4 mA/cm2 and an efficiency increase of 0.8%absolute could be achieved. With binary crossed gratings fabricated by a nanoimprint based process chain, a grating induced Jsc gain of 1.2 mA/cm2 and an efficiency gain of 0.7% absolute could be achieved. For the binary grating concept, cell thickness variations have also been performed. The increasing importance of the light trapping properties towards low solar cell thicknesses could be confirmed by an enhanced EQE in the long wavelength region (Jsc increase: 1.6 mA/cm2 for 150 μm and 1.8 mA/cm2 for 100 μm thick solar cells). The results are in very good agreement with simulations using the OPTOS modeling formalism. OPTOS enables the further analysis and optimization of grating concepts in silicon solar cells and modules. So a grating induced Jsc gain of 0.8 mA/cm2 is forecast for solar cells with pyramidal front side texture. On module level, still a grating induced Jsc gain of 0.6 mA/cm2 can be expected.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121344348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sparsity assisted phase retrieval of complex valued objects","authors":"Charu Gaur, K. Khare","doi":"10.1117/12.2227165","DOIUrl":"https://doi.org/10.1117/12.2227165","url":null,"abstract":"Iterative phase retrieval of complex valued objects (phase objects) suffers from twin image problem due to the presence of features of image and its complex conjugate in the recovered solution. The twin-image problem becomes more severe when object support is centro-symmetric. In this paper, we demonstrate that by modifying standard Hybrid-Input output (HIO) algorithm using an adaptive sparsity enhancement step, the twin-image problem can be addressed successfully even when the object support is centro-symmetric. Adaptive sparsity enhanced algorithm and numerical simulation for binary as well as gray scale phase objects are presented. The high quality phase recovery results presented here show the effectiveness of adaptive sparsity enhanced algorithm.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133916518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Rydberg impurity in a dense background gas (Conference Presentation)","authors":"T. Liebisch, Michael Schlagmüller, F. Engel, Karl M. Westphal, K. Kleinbach, F. Böttcher, R. Loew, S. Hofferberth, T. Pfau, J. Pérez-Ríos, C. Greene","doi":"10.1117/12.2227722","DOIUrl":"https://doi.org/10.1117/12.2227722","url":null,"abstract":"A single Rydberg atom impurity excited in a BEC is a system that can be utilized to measure the quantum mechanical properties of electron - neutral scattering andthe electron probability density of a Rydberg atom. The Rydberg electron – neutral atom scattering process, is a fundamental scattering process, which can be described via Fermi’s pseudopotential as V{vec{r},vec{R} )=2pi textit{a}[k(R)]delta^{(3)}(vec{r}-vec{R}). The scattering length is dependent on the momentum of the Rydberg electron, and therefore is dependent on the separation of the Rydberg electron from the ion core. At the classical outermost turning point of the electron, it has the slowest momentum leading to s-wave dominated scattering potentials 10’s of MHz in depth for n<40 (Greene et al. PRL 85 2458 (2000), Bendkowsky et al. PRL 105 163201 (2010)). In alkali atoms there is a shape resonance for p-wave scattering, which becomes relevant at ion-neutral separations of ~75nm (I.I. Fabrikant J.Phys B 19, 1527 (1985)). This shape resonance potential is several GHz deep, spanning the energy level spacing between n and n-1 principal quantum numbers. At high BEC densities of 5x10^14cm-3 the nearest neighbor spacing is less than 70nm. A Rydberg atom excited within a BEC, is an excitation of the Rydberg atom and all N neutral atoms located within the Rydberg orbit, described as nS+N x 5S. The nS+N x 5S state is density shifted from the Rydberg resonance. Not only does the distribution of atoms within the Rydberg orbit lead to a density shift, but, at these high densities, atoms excited in the nS+N x 5S state near the shape resonance potential cause large perturbations to the density shift, leading to a line broadening. Therefore the spectroscopic line shape of a Rydberg atom in a BEC allows us to probe the theoretically calculated p-wave shape resonance potential. Furthermore, we can observe and measure the dynamics of neutrals excited in the nS+N x 5S state. In the ultracold regime of a BEC, the background neutral atoms within the Rydberg orbit have kinetic energies of a few kHz, and experience large forces due to the GHz-deep shape resonance potentials. An atom dragged into this deep potential leads to an exothermic state-changing collision. We measure the timescale of this state-changing collision and compare to semi-classical calculations of the neutral atoms evolving in the potential of the two-particle nS+ 5S system. We also measure the change in energy from the original nS state to the product state, (n-4)L (L<3). On time scales shorter than the state-changing collisions, which for n<100 is on the order of 10 microseconds, the neutral atoms will evolve and collect in the shallower electron-neutral potentials, which mimic the electron probability density of the Rydberg atom.With n<100, the Rydberg atom has a diameter greater than 2 micrometers. With an imaging system with <1 micrometer resolution, we expect to observe a macroscopic change in the density profile of the BEC indica","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130987061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}