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Photonic realization of the relativistic Dirac oscillator  [PDF]
Stefano Longhi
Physics , 2010, DOI: 10.1364/OL.35.001302
Abstract: A photonic realization of the Dirac oscillator (DO), i.e. of the relativistic extension of the quantum harmonic oscillator, is proposed for light propagation in fiber Bragg gratings. Transmission spectra clearly show the existence of electron and positron bound states of the DO, corresponding to resonance modes above and below the Bragg frequency, as well as the asymmetry of the energy spectrum for electron and positron branches.
Activity coefficients of potassium chloride in aqueous solutions of potassium chloride and potassium phthalate
Marques,A.; Ferra,M.I.A.; Bandeira,M.H.;
Portugaliae Electrochimica Acta , 2006,
Abstract: mean activity coefficients of potassium chloride were determined in aqueous solutions of potassium chloride and potassium phthalate, in the temperature range 10-50 oc and ionic strength range 0.05-4 mol kg-1, from potentiometric measurements on a galvanic cell without liquid junction. by processing the results using the pitzer model, interaction parameters for potassium phthalate were calculated as well as their temperature dependence.
Activity coefficients of potassium chloride in aqueous solutions of potassium chloride and potassium phthalate  [cached]
A. Marques,M.I.A. Ferra,M.H. Bandeira
Portugaliae Electrochimica Acta , 2006,
Abstract: Mean activity coefficients of potassium chloride were determined in aqueous solutions of potassium chloride and potassium phthalate, in the temperature range 10-50 oC and ionic strength range 0.05-4 mol kg-1, from potentiometric measurements on a galvanic cell without liquid junction. By processing the results using the Pitzer model, interaction parameters for potassium phthalate were calculated as well as their temperature dependence.
Photonic Crystal-Based Sensing and Imaging of Potassium Ions  [PDF]
Christoph Fenzl,Michael Kirchinger,Thomas Hirsch,Otto S. Wolfbeis
Chemosensors , 2014, DOI: 10.3390/chemosensors2030207
Abstract: We report on a method for selective optical sensing and imaging of potassium ions using a sandwich assembly composed of layers of photonic crystals and an ion-selective membrane. This represents a new scheme for sensing ions in that an ionic strength-sensitive photonic crystal hydrogel layer is combined with a K +-selective membrane. The latter consists of plasticized poly(vinyl chloride) doped with the K +-selective ion carrier, valinomycin. The film has a red color if immersed into plain water, but is green in 5 mM KCl and purple at KCl concentrations of 100 mM or higher. This 3D photonic crystal sensor responds to K + ions in the 1 to 50 mM concentration range (which includes the K + concentration range encountered in blood) and shows high selectivity over ammonium and sodium ions. Sensor films were also imaged with a digital camera by exploiting the RGB technique.
Fiber Sensor Systems Based on Fiber Laser and Microwave Photonic Technologies  [PDF]
Hongyan Fu,Daru Chen,Zhiping Cai
Sensors , 2012, DOI: 10.3390/s120505395
Abstract: Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the development of novel fiber technology, more and more newly invented fiber technologies bring better and superior performance to fiber-optic sensing networks. In this paper, the applications of some advanced photonic technologies including fiber lasers and microwave photonic technologies for fiber sensing applications are reviewed. FBG interrogations based on several kinds of fiber lasers, especially the novel Fourier domain mode locking fiber laser, have been introduced; for the application of microwave photonic technology, examples of microwave photonic filtering utilized as a FBG sensing interrogator and microwave signal generation acting as a transversal loading sensor have been given. Both theoretical analysis and experimental demonstrations have been carried out. The comparison of these advanced photonic technologies for the applications of fiber sensing is carried out and important issues related to the applications have been addressed and the suitable and potential application examples have also been discussed in this paper.
Photonic bandgap fiber bundle spectrometer  [PDF]
Qu Hang,Bora Ung,Imran Syed,Ning Guo,Maksim Skorobogatiy
Physics , 2010, DOI: 10.1364/AO.49.004791
Abstract: We experimentally demonstrate an all-fiber spectrometer consisting of a photonic bandgap fiber bundle and a black and white CCD camera. Photonic crystal fibers used in this work are the large solid core all-plastic Bragg fibers designed for operation in the visible spectral range and featuring bandgaps of 60nm - 180nm-wide. 100 Bragg fibers were chosen to have complimentary and partially overlapping bandgaps covering a 400nm-840nm spectral range. The fiber bundle used in our work is equivalent in its function to a set of 100 optical filters densely packed in the area of ~1cm2. Black and white CCD camera is then used to capture spectrally "binned" image of the incoming light at the output facet of a fiber bundle. To reconstruct the test spectrum from a single CCD image we developed an algorithm based on pseudo-inversion of the spectrometer transmission matrix. We then study resolution limit of this spectroscopic system by testing its performance using spectrally narrow test peaks (FWHM 5nm-25nm) centered at various positions within the 450nm-700nm spectral interval. We find that the peak center wavelength can always be reconstructed within several percent of its true value regardless of the peak width or position. We believe that photonic bandgap fiber bundle-based spectrometers have a potential to become an important technology in multispectral imaging because of their simplicity (lack of moving parts), instantaneous response, and high degree of integration.
Physical realization of Photonic Klein Tunneling  [PDF]
S. Esposito
Physics , 2011, DOI: 10.1209/0295-5075/95/10002
Abstract: General physical conditions for the occurrence of photonic Klein tunneling are studied, where (controlled) spontaneous emission from the devices considered plays a key role. The specific example of a simple dielectric slab bounded by two dielectric half spaces with arbitrary refractive indices is worked out quite in detail, the measured reflection and transmission probabilities being calculated analytically. It is found that, in given cases, the measured reflection probability may be arbitrarily large (for large incident wavelengths) irrespective of the fact that the transmission probability is exponentially suppressed or not. Other interesting features of photonic Klein tunneling driven by (controlled) spontaneous emission are as well envisaged for practical applications.
Photonic realization of the quantum Rabi model  [PDF]
Andrea Crespi,Stefano Longhi,Roberto Osellame
Physics , 2011, DOI: 10.1103/PhysRevLett.108.163601
Abstract: We realize a photonic analog simulator of the quantum Rabi model, based on light transport in femtosecond-laser-written waveguide superlattices, which provides an experimentally accessible testbed to explore the physics of light-matter interaction in the deep strong coupling regime. Our optical setting enables to visualize dynamical regimes not yet accessible in cavity or circuit quantum electrodynamics, such as bouncing of photon number wave packets in parity chains of Hilbert space.
Scalable fiber integrated source for higher-dimensional path-entangled photonic quNits  [PDF]
Christoph Schaeff,Robert Polster,Radek Lapkiewicz,Robert Fickler,Sven Ramelow,Anton Zeilinger
Physics , 2012, DOI: 10.1364/OE.20.016145
Abstract: Integrated photonic circuits offer the possibility for complex quantum optical experiments in higher-dimensional photonic systems. However, the advantages of integration and scalability can only be fully utilized with the availability of a source for higher-dimensional entangled photons. Here, a novel fiber integrated source for path-entangled photons in the telecom band at 1.55\mum using only standard fiber technology is presented. Due to the special design the source shows good scalability towards higher-dimensional entangled photonic states (quNits), while path entanglement offers direct compatibility with on-chip path encoding. We present an experimental realization of a path-entangled two-qubit source. A very high quality of entanglement is verified by various measurements, i.a. a tomographic state reconstruction is performed leading to a background corrected fidelity of (99.45+-0.06)%. Moreover, we describe an easy method for extending our source to arbitrarily high dimensions.
Highly Nonlinear and Birefringent Spiral Photonic Crystal Fiber  [PDF]
S. Revathi,Srinivasa Rao Inbathini,Rizwan Ali Saifudeen
Advances in OptoElectronics , 2014, DOI: 10.1155/2014/464391
Abstract: We propose and design a spiral photonic crystal fiber with elliptical air holes for achieving high birefringence, large nonlinearity, and negative dispersion. The structure is designed using chalcogenide glass (As2S3) for different ellipticity ratios of air holes in the cladding and the effect on various properties is observed. The proposed structure has birefringence of the order 10?2, nonlinearity of 26739.42?W?1?m?1, and dispersion of ?1136.69 at 0.85?μm. An accurate numerical approach based on finite element method is used for the design and simulation of the structure. Due to high birefringence and negative dispersion, the proposed structure can be used for polarization control and dispersion compensation, respectively. 1. Introduction Photonic crystal fiber is a class of optical fiber which is based on the properties of photonic crystal. Due to its unique properties photonic crystal fiber finds a lot of applications in optical fiber communication [1]. In standard fiber, the guiding mechanism is by a region with higher refractive index than the surrounding cladding. In case of PCFs, the microstructure of core and air holes surrounding it provide the required index difference. The basic principle of operation of a PCF is based either on modified total internal reflection in which light is guided in solid core which depends on the relative refractive index difference between the core and the microstructure cladding or on photonic band gap effect in which light is confined by a photonic band gap that is created by the microstructure cladding [2–4]. Such fiber allows the propagation of light through lower index core or even through hollow core. Compared to conventional fiber, PCFs provide large freedom in the design which allows the flexibility in various properties including birefringence, flattened and negative dispersion, effective area, and nonlinearity. Apart from the conventional hexagonal lattice, different types of air hole arrangements are proposed for achieving many useful properties [5–7]. In equiangular spiral photonic crystal fiber, the air holes are distributed around the solid core so that the arrangement gives a spiral pattern. The design parameters for spiral PCF include number of spiral arms, number of air holes in each spiral arm, and core diameter. Various useful properties can be obtained by tailoring these parameters to the PCF design. Equiangular spiral PCF (ES-PCF) with small effective area and large nonlinearity has been reported [8]. Spiral PCF with elliptical core is designed [9] which has large birefringence and
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