### Early Posting

#### Accepted papers to appear in an upcoming issue

OSA now posts prepublication articles as soon as they are accepted and cleared for production. See the FAQ for additional information.

**Articles 1 to 19 of 19**

## July

Optical forces from evanescent Bessel beams, multiple reflections and Kerker conditions in magnetodielectric spheres and cylinders

- received 05/13/2014; accepted 07/25/2014; posted 07/28/2014; Doc. ID 211847
- [full text: PDF (765) KB)]
- Abstract: In this work we address, first, the optical force on a magnetodielectric particle on a flat dielectric surface due to an evanescent Bessel beam and, second, the effects on the force of multiple scattering with the substrate. For the first question we find analytical solutions showing that due to the interference of the excited electric and magnetic particle dipoles, the vertical force unusually pushes the object out from the plane. The incident wavelength rules whether the illumination constitutes, or not, an optical trap. As for the second problem, we make a 2D study with a single evanescent plane wave, and we present the Kerker conditions, (so far established for spheres), for magnetodielectric cylinders; showing that in p-polarization those are practically reproduced and are associated to minima of the horizontal and vertical forces. Also we show the existence of negative radiation pressure parallel to the substrate.

**Keywords (OCIS):**

- (240.6690) Optics at surfaces : Surface waves
- (290.4210) Scattering : Multiple scattering
- (290.5850) Scattering : Scattering, particles
- (350.4855) Other areas of optics : Optical tweezers or optical manipulation

Molding the flow of light with a magnetic field: plasmonic cloaking and directional scattering

- received 04/21/2014; accepted 07/22/2014; posted 07/24/2014; Doc. ID 210579
- [full text: PDF (1751) KB)]
- Abstract: We investigate electromagnetic scattering and plasmonic cloaking in a system composed by a dielectric cylinder coated with a magneto-optical shell. In the long-wavelength limit we demonstrate that the application of an external magnetic field can not only switch on and off the cloaking mechanism but also mitigate losses, as the absorption cross-section is shown to drop sharply precisely at the cloaking operation frequency band. We also show that the angular distribution of the scattered radiation can be effectively controlled by applying an external magnetic field, allowing for a swift change in the scattering pattern. By demonstrating that these results are feasible with realistic, existing magneto-optical materials, such as graphene epitaxially grown on SiC, we suggest that magnetic fields could be used as an effective, versatile external agent to tune plasmonic cloaks and to dynamically control electromagnetic scattering in an unprecedented way, we hope that these results may find use in disruptive photonic technologies.

**Keywords (OCIS):**

- (160.3820) Materials : Magneto-optical materials
- (230.0230) Optical devices : Optical devices
- (230.3205) Optical devices : Invisibility cloaks
- (290.5839) Scattering : Scattering, invisibility

Truncation of the flash-lag effect by a fixed spatial landmark

- received 06/03/2014; accepted 07/21/2014; posted 07/23/2014; Doc. ID 213276
- [full text: PDF (363) KB)]
- Abstract: The flash-lag effect is a visual illusion where a moving image is perceived to be advanced in its spatial location relative to a flashed image. Multiple studies have shown that the flash-lag effect can be enhanced by increasing the uncertainty of the moving and/or flashed images. However, little is known about the effect of perceptually irrelevant visual objects on the flash-lag effect. We were interested to see whether a perceptually irrelevant spatial landmark might reduce uncertainty and hence reduce the flash-lag effect. We placed a fixed bar between moving and flashed bars while measuring the flash-lag effect in six subjects. For most subjects, the fixed bar substantially truncated the flash-lag effect. The effect was maximal when the fixed bar was aligned with the flashed bar and decreased when the fixed bar was positioned more peripherally. A second experiment with two subjects used a smaller fixed bar; the smaller bar had less truncation effect in one subject, while the other subject showed similar truncation regardless of the fixed bar size. Our results support models that place the locus of the flash-lag effect in higher-order brain areas, e.g. the parietal lobe.

**Keywords (OCIS):**

- (330.5510) Vision, color, and visual optics : Psychophysics
- (330.7310) Vision, color, and visual optics : Vision

Maximum absorption by homogeneous magneto-dielectric sphere

- received 03/14/2014; accepted 07/17/2014; posted 07/21/2014; Doc. ID 208217
- [full text: PDF (542) KB)]
- Abstract: In order to obtain a benchmark for electromagnetic energy harvesting we investigate the maximum absorption efficiency by a magneto-dielectric homogeneous sphere illuminated by a plane wave and we arrive at several novel results. For electrically small spheres we show that the optimal relative permeability and permeability of natural materials is (1+i3) independent of sphere size, while that of metamaterials is (-2+iδ) where the imaginary part δ decreases strongly with decreasing sphere size. For larger spheres we show that while maximum absorption efficiency occurs at the resonances of the spherical modes there exists a wide plateau of high absorption efficiency when relative permittivity and permeability are equal; in the case of free-space electrical radius κ=1, the absorption efficiency becomes 2.8 when relative permittivity and permeability exceed (10+i2). The investigation is analytic/numerical and based on the Lorenz-Mie theory combined with the Optical Theorem.

**Keywords (OCIS):**

- (290.0290) Scattering : Scattering
- (290.4020) Scattering : Mie theory
- (050.6624) Diffraction and gratings : Subwavelength structures

On the Instrument Profile of Slit Spectrographs

- received 06/02/2014; accepted 07/17/2014; posted 07/28/2014; Doc. ID 213098
- [full text: PDF (473) KB)]
- Abstract: We derive an analytic expression for the instrument profile of a slit spectrograph, also known as the line spread function. While this problem is not new, our treatment relies on the operatorial approach to the description of diffractive optical systems, which provides a general framework for the analysis of the performance of slit spectrographs under different illumination conditions. Based on our results, we propose an approximation to the spectral resolution of slit spectrographs, taking into account diffraction effects and sampling by the detector, which improves upon the often adopted approximation based on the root-sum-square of the individual contributions from the slit, the grating, and the detector pixel.

**Keywords (OCIS):**

- (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
- (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation

Crossover regime of optical vortices generation via electrooptic nonlinearity: The problem of optical vortices with the fractional charge generated by crystals

- received 04/30/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 211145
- [full text: PDF (2961) KB)]
- Abstract: In this work we analyze the behavior of topological defects of optical indicatrix orientation in-duced by a conically shaped electric field in crystals in a crossover regime that appears at inter-mediate fields separating the regimes of prevailing Pockels and Kerr electro-optic nonlinearities. We have found that increase in the electric voltage applied to a crystal induces neither topological defects with the strengths being not multiples of ½, nor the optical vortices with fractional charges. Instead, there appear some additional topological defects of the optical indica-trix orientation, of which behavior we have studied in detail.

**Keywords (OCIS):**

- (190.3270) Nonlinear optics : Kerr effect
- (260.0260) Physical optics : Physical optics
- (260.1180) Physical optics : Crystal optics
- (260.1440) Physical optics : Birefringence
- (260.6042) Physical optics : Singular optics

Asymmetric Bessel-Gauss Beams

- received 05/13/2014; accepted 07/16/2014; posted 07/17/2014; Doc. ID 212058
- [full text: PDF (3348) KB)]
- Abstract: We propose a three-parameter family of asymmetric Bessel-Gauss (aBG) beams with integer and fractional orbital angular momentum (OAM). The aBG beams are described by the product of a Gaussian function by the n-th order Bessel function of the first kind of complex argument, having finite energy. The aBG beam's asymmetry degree depends on a real parameter c ≥ 0: at с = 0, the aBG beam is coincident with a conventional radially symmetric Bessel-Gauss (BG) beam; with increasing c, the aBG beam acquires a semi-crescent shape, then becoming elongated along the y-axis and shifting along the x-axis for c >> 1. In the initial plane, the intensity distribution of the aBG beams has a countable number of isolated optical nulls on the x-axis, which result in optical vortices with unit topological charge and opposite signs on the different sides of the origin. As the aBG beam propagates, the vortex centers undergo a non-uniform rotation with the entire beam about the optical axis (с >> 1), making a π/4 turn at the Rayleigh range and another π/4 turn after travelling the rest distance. At different values of the c parameter, the optical nulls of the transverse intensity distribution change their position, thus changing the OAM that the beam carries. An isolated optical null on the optical axis generates an optical vortex with topological charge n. A vortex laser beam shaped as a rotating semi-crescent has been generated using a spatial light modulator.

**Keywords (OCIS):**

- (050.1960) Diffraction and gratings : Diffraction theory
- (350.5500) Other areas of optics : Propagation
- (050.4865) Diffraction and gratings : Optical vortices

Internal and near-surface electromagnetic fields for a dielectric spheroid illuminated by a zero-order Bessel beam

- received 06/13/2014; accepted 07/14/2014; posted 07/21/2014; Doc. ID 214064
- [full text: PDF (1066) KB)]
- Abstract: Within the framework of generalized Lorenz-Mie theory (GLMT), scattering from a homogeneous spheroidal particle illuminated by an on-axis zero-order Bessel beam is formulated analytically, with special attention paid to the investigation of internal and near-surface field. Numerical results concerning the spatial distributions of internal and near-surface field are presented for various parameter values, such as half-cone angle of the incident zero-order Bessel beam, major axis, minor axis and refractive index of the spheroid. The study on internal and near-surface field distribution would contribute to the understanding of Bessel beam scattering by nonspherical particles with sizes close to the incident wavelength.

**Keywords (OCIS):**

- (140.3430) Lasers and laser optics : Laser theory
- (260.2110) Physical optics : Electromagnetic optics
- (290.4020) Scattering : Mie theory
- (290.5850) Scattering : Scattering, particles

Realization of first order optical systems using thin convex lenses of fixed focal length

- received 04/08/2014; accepted 07/14/2014; posted 07/25/2014; Doc. ID 209647
- [full text: PDF (410) KB)]
- Abstract: A general axially symmetric first order optical system is realized using free propagation and thin convex lenses of fixed focal length. It is shown that not more than five convex lenses of fixed focal length are required to realize the most general first order system, with the required number of lenses depending on the situation. The free propagation distances are evaluated explicitly in each situation. The optimality of the decomposition obtained in each situation is brought out. Decompositions for some familiar subgroups of $SL_2(\mathbb{R})$ are also worked out. Convex or concave lens of arbitrary focal length are realized using three or two convex lenses of fixed focal length respectively. It is further shown that three convex lenses of arbitrary focal length are sufficient to realize the most general first order optical system.

**Keywords (OCIS):**

- (070.2580) Fourier optics and signal processing : Paraxial wave optics
- (070.2590) Fourier optics and signal processing : ABCD transforms
- (080.2730) Geometric optics : Matrix methods in paraxial optics
- (080.3620) Geometric optics : Lens system design
- (080.2468) Geometric optics : First-order optics

Analysis of Dyakonov Surface Waves Existing at the Interface of an Isotropic Medium and a Conductor-Backed Uniaxial Slab

- received 03/10/2014; accepted 07/12/2014; posted 07/21/2014; Doc. ID 207924
- [full text: PDF (623) KB)]
- Abstract: In this paper, Dyakonov surface waves (Dyakonov SWs) existing at the interface between a semi-infinite isotropic medium and a conductor-backed uniaxial slab are analyzed with the help of an exponential-matrix-method. The boundary conditions at the interface are formulated using eigenvalues and eigenvectors of two partnering media. Based on this, the existence region of Dyakonov SWs is formulated and proven to be highly dependent on the thickness of the uniaxial slab. Some relevant characteristics of the propagating Dyakonov SWs, such as the intensity distribution of the propagation constant, and the electric- and magnetic-field distributions, are introduced and investigated. The analysis is of great importance for the control and utilization of Dyakonov SWs in practical designs.

**Keywords (OCIS):**

- (160.1190) Materials : Anisotropic optical materials
- (240.6690) Optics at surfaces : Surface waves
- (350.5500) Other areas of optics : Propagation

Geometric Algebra Description of Polarization Mode Dispersion, Polarization Dependent Loss and Stokes Tensor Transformations

- received 03/03/2014; accepted 07/12/2014; posted 07/14/2014; Doc. ID 207487
- [full text: PDF (367) KB)]
- Abstract: This paper demonstrates that numerous calculations involving polarization transformations can be condensed by employing suitable geometric algebra formalism. For example, to describe polarization mode dispersion and polarization dependent loss both the material birefringence and differential loss enter as bivectors and can be combined into a single symmetric quantity. Their frequency and distance evolution as well as that of the Stokes vector through an optical system can then each be expressed as a single compact expression, in contrast to the corresponding Mueller matrix formulations. The intrinsic advantage of the geometric algebra framework is further demonstrated by presenting a simplified derivation of generalized Stokes parameters that include the electric field phase. This procedure simultaneously establishes the tensor transformation properties of these parameters.

**Keywords (OCIS):**

- (060.2310) Fiber optics and optical communications : Fiber optics
- (260.5430) Physical optics : Polarization

Transmission of Gaussian beam through a gyrotropic cylinder

- received 04/23/2014; accepted 07/11/2014; posted 07/21/2014; Doc. ID 210666
- [full text: PDF (555) KB)]
- Abstract: An exact analytical solution to the transmission of a Gaussian beam through a gyrotropic cylinder is formulated in terms of a cylindrical vector wave function expansion form. By applying the continuous boundary conditions of electromagnetic fields, the unknown expansion coefficients of the scattered and internal fields are determined. For a localized beam model, numerical results are presented for the normalized near-surface and internal field intensity distributions, and the propagation characteristics are discussed concisely.

**Keywords (OCIS):**

- (140.3430) Lasers and laser optics : Laser theory
- (260.2110) Physical optics : Electromagnetic optics
- (290.4020) Scattering : Mie theory

Simultaneous estimation of phase and phase derivative using difference equation representation of the interference field

- received 06/13/2014; accepted 07/10/2014; posted 07/21/2014; Doc. ID 214069
- [full text: PDF (593) KB)]
- Abstract: A computationally efficient technique for fringe analysis in digital holographic interferometry using difference equation representation of the interference field is presented. The spatially-varying coefficient of the difference equation is accurately estimated by constraining it in the subspace spanned by the linearly independent basis functions. The estimated coefficient provides an accurate estimation of the interference phase derivative and enables the linear estimation of the interference field. Thereupon, the interference phase is estimated using a simple unwrapping algorithm. The performance of the proposed method is validated with the help of simulation and experimental results.

**Keywords (OCIS):**

- (120.2880) Instrumentation, measurement, and metrology : Holographic interferometry
- (120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
- (090.1995) Holography : Digital holography

DLAB: A Class of Daylight-Based Uniform Color Space

- received 03/06/2014; accepted 07/07/2014; posted 07/07/2014; Doc. ID 206764
- [full text: PDF (791) KB)]
- Abstract: CIELAB is based on the CIE 1931 color matching functions. If we are given a new set of color matching functions, how do we define a CIELAB-like uniform color space for the new functions? This problem arises when the CIE recommended its physiological cone fundamentals in 2006 and is considering a new set of color matching functions based on them. In fact, the same problem exists for many practical applications in digital imaging. Typical solutions involve using illuminant-dependent color correction matrices to transform the device-dependent color space into the CIE XYZ color space. This conversion process suffers information loss unless the two sets of color matching functions are linear combinations of each other. In this paper, we propose a design process that allows us to develop a CIELAB-like color space using the native sensor fundamentals. The basic idea is to choose the daylight locus as the yellow-blue opponent color process. We call this class of color space DLAB. We describe the design procedures and compare the resulting Munsell color uniformity under CIELAB$(L^*,a^*,b^*)$ and DLAB$(L^+,a^+,b^+)$.

**Keywords (OCIS):**

- (110.0110) Imaging systems : Imaging systems
- (330.0330) Vision, color, and visual optics : Vision, color, and visual optics
- (330.1690) Vision, color, and visual optics : Color
- (330.1710) Vision, color, and visual optics : Color, measurement
- (330.1730) Vision, color, and visual optics : Colorimetry

BER of Focused Gaussian Beams in Weak Oceanic Turbulence

- received 04/03/2014; accepted 07/05/2014; posted 07/07/2014; Doc. ID 209542
- [full text: PDF (480) KB)]
- Abstract: Formulation of the on-axis scintillation index of focused Gaussian beam in weak oceanic turbulence is derived by using Rytov method and using this formulation, the average bit error rate (BER) is evaluated. The scintillation indices of collimated, focused Gaussian, plane and spherical beams are compared. Scintillation index and BER versus the average signal to noise SNR found by using the log-normal distributed intensity for the collimated and focused Gaussian beams are exhibited for various source sizes α, focal lengths , the rate of dissipation of the mean squared temperature , and the rate of dissipation of turbulent kinetic energy per unit mass of fluid . Focused beams are found to have important advantage against the collimated beams. For the focused beam, as the source size increases, the scintillation index and BER decrease. When the focal length is equal to the propagation length, BER is found to possess the smallest value. BER is proportional to , however, inversely proportional to ε.

**Keywords (OCIS):**

- (010.0010) Atmospheric and oceanic optics : Atmospheric and oceanic optics
- (010.3310) Atmospheric and oceanic optics : Laser beam transmission
- (010.4450) Atmospheric and oceanic optics : Oceanic optics
- (140.3295) Lasers and laser optics : Laser beam characterization
- (010.4455) Atmospheric and oceanic optics : Oceanic propagation

Asymmetric information hiding and noise-free recovery based on rotating analyzer ellipsometry and QR code

- received 04/04/2014; accepted 07/02/2014; posted 07/03/2014; Doc. ID 209567
- [full text: PDF (2011) KB)]
- Abstract: We report for the first time an asymmetric optical information hiding method based on rotating analyzer ellipsometry technique. This asymmetric hiding architecture not only avoids the interception of keys during transmission or distribution but also makes the cyphertext more inconspicuous for attackers. A new kind of optical trapdoor one-way function is constructed based on the fact that state of polarization (SOP) of elliptical polarized light cannot be recovered with only the knowledge of intensity captured after passing through a linear polarizer. Meanwhile, the SOP of polarization ellipse could be calculated by rotating the polarizer to record two scenes of intensity after it. Introduction of quick response (QR) code as a container leads to a noise-free recovery for original information and enhances practicality of the proposed cryptosystem with versatile key sensitivity and fault tolerance capability. Numerical simulation results that support theoretical analysis are presented. An analysis on the relationship between hiding effect or quality of decryption and parameters of the algorithm is also provided.

**Keywords (OCIS):**

- (260.5430) Physical optics : Polarization
- (100.4998) Image processing : Pattern recognition, optical security and encryption

## June

Fast reconstruction of fluorescence molecular tomography via a permissible region extraction strategy

- received 03/11/2014; accepted 06/29/2014; posted 07/07/2014; Doc. ID 208033
- [full text: PDF (1798) KB)]
- Abstract: In order to get precise reconstruction results in fluorescence molecular tomography (FMT), large-scale matrix equations would be solved in the inverse problem generally. Thus, much time and memory needs to be consumed. In this paper, a permissible region extraction strategy is proposed to solve this problem. Firstly, a preliminary reconstruction result is rapidly obtained using the weight matrix compressed by principal component analysis (PCA) or uniform sampling. And then the reconstructed target area in this preliminary result is considered as a priori permissible region to guide the final reconstruction. This strategy has been demonstrated in phantom experiments with single and double fluorescent targets. The results illustrate that the proposed strategy can accelerate image reconstruction in FMT almost without quality degradation.

**Keywords (OCIS):**

- (100.3010) Image processing : Image reconstruction techniques
- (100.3190) Image processing : Inverse problems
- (110.6960) Imaging systems : Tomography
- (260.2510) Physical optics : Fluorescence

Phase Retrieval with Unknown Sampling Factors via the 2D Chirp z-Transform

- received 05/07/2014; accepted 06/29/2014; posted 07/14/2014; Doc. ID 211626
- [full text: PDF (2184) KB)]
- Abstract: We derive analytic gradient of a phase retrieval error metric with respect to the sampling factor or the f-number that produced the measured point-spread function. This allows us to efficiently optimize over the sampling factor, thereby improving the accuracy of the phase estimate. Computer simulation results show its effectiveness.

**Keywords (OCIS):**

- (010.7350) Atmospheric and oceanic optics : Wave-front sensing
- (100.5070) Image processing : Phase retrieval
- (110.6770) Imaging systems : Telescopes

## February

(CV) Independence and interaction of luminance and chromatic contributions to spatial hyperacuity performance

- received 09/30/2013; accepted 02/02/2014; posted 02/03/2014; Doc. ID 198653
- [full text: PDF (1336) KB)]
- Abstract: Here we test interactions of luminance and chromatic input to spatial hyperacuity mechanisms. First, we tested alignment with matching or mismatching (contrast polarity or modality) grating pairs that were adjusted to detection threshold. Thresholds with mismatched pairs were significantly elevated. Second, we determined alignment acuity as a function of luminance or chromatic contrast alone or in the presence of contrast pedestals. For in-phase pedestal conditions, performance followed the envelope of the more sensitive mechanism. However, polarity reversals revealed an asymmetric effect for luminance and chromatic conditions. This suggests that luminance can overrule chromatic mechanisms in hyperacuity; we interpret these findings in the context of spatial mechanisms.

**Keywords (OCIS):**

- (330.1720) Vision, color, and visual optics : Color vision
- (330.5510) Vision, color, and visual optics : Psychophysics
- (330.6100) Vision, color, and visual optics : Spatial discrimination

**Articles 1 to 19 of 19**