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Early Posting

Accepted papers to appear in an upcoming issue

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Articles 1 to 20 of 164 Next Page >>


Concept of annular vector beam generation at terahertz wavelength through a nonlinear parametric process

  • Kyosuke Saito, Tadao Tanabe, and Yutaka Oyama
  • received 11/17/2014; accepted 03/03/2015; posted 03/03/2015; Doc. ID 226982
  • [full text: PDF (801) KB)]
  • Abstract: In this paper, we describe our theoretical investigation and calculations for a terahertz (THz)-wave profile generated by difference frequency mixing (DFM) of focused, cylindrically symmetric, and polarized optical vector beams. Using vector diffraction theory, the second-order nonlinear polarization was estimated from the electric field components of the optical pump beams penetrating uniaxial, birefringent nonlinear optics crystals (NLO), GaSe and CdSe. The approximate beam patterns of the THz waves were simulated using DFM formulation. The intensity patterns of the THz waves for GaSe and CdSe showed sixfold symmetry and cylindrical symmetry, respectively, based on the nonlinear susceptibility tensor of the crystals. As the phase-matching angle θPM was constant with respect to the c-axis of the NLO crystals, an annular vector beam with a narrow width was expected.

Keywords (OCIS):

  • (000.4430) General : Numerical approximation and analysis
  • (260.1960) Physical optics : Diffraction theory
  • (260.3090) Physical optics : Infrared, far
  • (260.5430) Physical optics : Polarization
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Correcting temperature dependence in miniature spectrometers used in cold polar environments

  • Samuel Laney, Hangzhou Wang, Hong Song, and Ying Chen
  • received 11/26/2014; accepted 03/03/2015; posted 03/03/2015; Doc. ID 228651
  • [full text: PDF (3504) KB)]
  • Abstract: Measurement biases arising from changes in temperature can be a major concern when using miniature spectrometers in extreme environments. Here, temperature-related biases of a low-power field spectrometry system comprised of a nontemperature-stabilized CMOS miniature monolithic spectrometer and custom driver electronics were examined between +25.6 to -40 °C, well below the stated operating range of this particular spectrometer. Using these observations, a predictive model was developed to estimate the dark output of the spectrometer within this extended operating range. This information was used to correct the signal at any measured integration time and temperature to that which would be measured at a reference integration time and temperature. This approach provides a general framework for assessing temperature dependence of monolithic spectrometers whose field use will occur at temperatures outside of the range examined by the manufacturer.

Keywords (OCIS):

  • (300.6190) Spectroscopy : Spectrometers
  • (300.6550) Spectroscopy : Spectroscopy, visible

Small displacement measurements based on an angular-deviation amplifier and interferometric phase detection

  • Ming-Hung Chiu, Wei-Chou Chen, and Chen-Tai Tan
  • received 11/27/2014; accepted 03/03/2015; posted 03/03/2015; Doc. ID 228665
  • [full text: PDF (919) KB)]
  • Abstract: We propose a method for small displacement measurement based on the angle deviation to phase change transformation. The phase change of Common-Path Heterodyne Interferometry (CPHI) due to the angle deviation of incidence of a light at interfaces caused by the displacement is detected by a lock-in amplifier. For obtaining more accurate results, we used an angular amplifier to increase the angle deviation and utilized a surface plasmon resonance (SPR) sensor to enhance the performance of phase detection. When a translator moving one of two faceto- face plane mirrors at an end and then rotating it a small angle, a light is incident onto the mirrors and reflected N times, and the outgoing light is deflected N times of the angle and incident into a SPR sensor. Thus the phase shift due to the angle deviation is amplified N times. The accumulated phase shift is proportional to the amplified angle deviation and displacement. Therefore, the phase change is obtained, the displacement is measured. The amount of movement required can be as low as 0.13 μm without an SPR sensor or 0.08 μm with an SPR sensor. The maximum measurement range can reach 1000 μm.

Keywords (OCIS):

  • (040.2840) Detectors : Heterodyne
  • (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
  • (120.3180) Instrumentation, measurement, and metrology : Interferometry
  • (120.5050) Instrumentation, measurement, and metrology : Phase measurement
  • (240.6680) Optics at surfaces : Surface plasmons

Dielectric function of nano-granular ZnO very thin layers with different states of growth

  • Mickael Gilliot, aomar hadjadj, and Aotmane En Naciri
  • received 01/14/2015; accepted 03/03/2015; posted 03/03/2015; Doc. ID 231593
  • [full text: PDF (1413) KB)]
  • Abstract: ZnO layers consisting in grains closely packed together are grown using a sol-gel synthesis and spin-coating deposition process. The morphologies are characterized by atomic force microscopy and X-ray diffraction, and their optical properties are investigated by spectroscopic ellipsometry at the different stages of the growth process. The optical observations are correlated with evolution of morphology and orientation. Two remarkable evolutions are observed: gradual evolution of morphology, crystallinity and excitonic contribution with the first deposition steps; and transformation from a poorly oriented to a c-axis oriented crystalline state featuring a large contribution of bound excitons after thermal annealing. A modified Elliott model is used to obtain the optical parameters of ZnO, including bandgap and exciton energies. A simple growth mechanism is proposed to explain the evolution of the layers with the different deposition steps.

Keywords (OCIS):

  • (160.4760) Materials : Optical properties
  • (160.6060) Materials : Solgel
  • (240.0310) Optics at surfaces : Thin films
  • (310.3840) Thin films : Materials and process characterization
  • (160.4236) Materials : Nanomaterials
  • (240.2130) Optics at surfaces : Ellipsometry and polarimetry

Parametric analysis of damage probability: a tool to identify weak layers within multilayer coatings

  • Gintarė Batavičiūtė, Andrius Melninkaitis, Linas Smalakys, and Egidijus Pupka
  • received 01/13/2015; accepted 03/03/2015; posted 03/03/2015; Doc. ID 231997
  • [full text: PDF (3376) KB)]
  • Abstract: The role of defects, inherent to fused silica substrate due to polishing and deposition processes, is interpreted in terms of laser induced damage probability. Changes of damage threshold behavior are observed in bare substrate, monolayer and multilayer coatings after irradiation with UV (355 nm) nanosecond laser pulses at different angles of incidence (0$^0$ and 45$^0$) and polarizations (s, p). Statistical damage probability models are constructed for experimental data approximation. Effects of light intensification by standing waves within multilayer coatings and localization of the defects (surface, interface and bulk) are considered as key factors within presented study. Polishing defects are shown to be the limiting factor in case of uncoated fused silica (FS) sample, as well as SiO$_2$ and HfO$_2$ monolayer coated substrates. The obtained results also suggest that damage threshold of almost identical sublayers constituting highly reflective multilayer HfO$_2$/SiO$_2$ coating with central 355 nm wavelength is a function of sublayer depth.

Keywords (OCIS):

  • (140.3330) Lasers and laser optics : Laser damage
  • (160.4670) Materials : Optical materials
  • (240.5450) Optics at surfaces : Polishing
  • (310.6860) Thin films : Thin films, optical properties

Broadband Single Polarization Single Mode Photonic Crystal Fibers With Three Different Background Materials

  • hui li, Shuguang Li, Wan Zhang, jianshe li, and Guowen An
  • received 01/09/2015; accepted 03/03/2015; posted 03/03/2015; Doc. ID 232099
  • [full text: PDF (2483) KB)]
  • Abstract: A modified structure of single-polarization single-mode(SPSM) photonic crystal fiber(PCF) with different background materials is presented and analyzed by using the full-vector finite element method. Simulation results confirmed that the proposed PCF can realized low-loss SPSM on three wavebands with the same structure and different background materials. The wavebands are 1.46 to 1.60μm for silica-based fiber,1.97 to 2.3μm for lead silicate glass fiber,and 3.16 to 3.58μm for Chalcogenide glass fiber.For three PCFs with different background materials, only the slow-axis mode exists and the confinement loss is less than 100dB/m in the SPSM wavebands.

Keywords (OCIS):

  • (260.1440) Physical optics : Birefringence
  • (260.5430) Physical optics : Polarization
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

Analytical model of Optical path difference in end-pumped Yb:YAG thin disk laser with nonuniform pumping light

  • Guangzhi Zhu, Xiao Zhu, Wang Zexiong, Dai Zhongxiong, and Zhu Chuanghong
  • received 01/21/2015; accepted 03/02/2015; posted 03/03/2015; Doc. ID 233018
  • [full text: PDF (6713) KB)]
  • Abstract: An analytical model of thermal effect and Optical Path Difference (OPD) of thin disk laser is developed by an arbitrary form pumping spot. Based on the analytical model, the distribution of temperature, stress, strain can be derived using the Super-Gaussian form pumping spot. The total OPD caused by temperature gradient, axial thermal strain, thermal strain-induced birefringence and deformation of the thin disk crystal is discussed for different Super-Gaussian factor and separated into spherical and aspherical part. The analytical results show that the asperical part of OPD is the main reason leading the decreasing of laser beam quality and closely related to Super-Gaussian factors, which are very useful for thin disk laser design and evaluation.

Keywords (OCIS):

  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.6810) Lasers and laser optics : Thermal effects
  • (350.6830) Other areas of optics : Thermal lensing
  • (140.3615) Lasers and laser optics : Lasers, ytterbium

Highly Birefringent Photonic Crystal Fiber with Ultra-flattened Negative Dispersion over S+C+L+U Bands

  • MD SELIM HABIB and Mitul Mitul Khandker
  • received 01/26/2015; accepted 03/02/2015; posted 03/03/2015; Doc. ID 233290
  • [full text: PDF (531) KB)]
  • Abstract: We present a new cladding design for photonic crystal fiber (PCF) on a decagonal structure to achieve simultaneously ultrahigh birefringence and ultra-flattened large negative dispersion. Numerical results confirm that the proposed PCF exhibits ultra-flattened large negative dispersion over S + C + L + U wavelength bands and average dispersion of about −558.96 ps/nm/km with absolute dispersion variation of 9.7 ps/nm/km from 1460 to 1675 nm (215-nm bandwidth) and a high birefringence of 0.0299 at 1500 nm wavelength.

Keywords (OCIS):

  • (260.1440) Physical optics : Birefringence
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

Holographic fabrication of nano-antenna templates through single reflective optical element

  • Yuankun Lin, Jeff Lutkenhaus, Hualiang Zhang, Usha Philipose, Jun Ding, Jingbiao Cui, and David George
  • received 02/04/2015; accepted 03/02/2015; posted 03/03/2015; Doc. ID 233779
  • [full text: PDF (1167) KB)]
  • Abstract: In this paper, we present a single-reflective-optical-element based approach for the control of laser phase, polarization, and beam intensity for the holographic fabrication of nano-antenna templates. The single-optical-element can be designed and precisely printed by a 3D printer. The holographic fabrication is demonstrated in both negative and positive photoresist. The fabricated pattern is in agreement with simulations. The control of nanogap size of nano-antennas is discussed in term of capabilities of single-optical-element approach.

Keywords (OCIS):

  • (220.3740) Optical design and fabrication : Lithography
  • (220.4610) Optical design and fabrication : Optical fabrication
  • (220.4241) Optical design and fabrication : Nanostructure fabrication

Establishment and application of the 0/45 reflectance factor scale over the shortwave infrared

  • Catherine Cooksey, David Allen, Benjamin Tsai, and Howard Yoon
  • received 12/17/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 230647
  • [full text: PDF (689) KB)]
  • Abstract: This paper describes the establishment and application of the 0/45 reflectance factor scale in the shortwave infrared (SWIR) from 1100 nm to 2500 nm. Design, characterization, and the demonstration of a 4-stage, extended indium-gallium-arsenide radiometer to make reflectance measurements in the SWIR have been previously discussed. Here, we focus on the incorporation of the radiometer into the national reference reflectometer, its validation through comparison measurements, and the uncertainty budget. Next, this capability is applied to the measurement of three different diffuser materials. The 0/45 spectral reflectance factors for these materials are reported and compared to their respective 6/di spectral reflectance factors.

Keywords (OCIS):

  • (120.1840) Instrumentation, measurement, and metrology : Densitometers, reflectometers
  • (120.5700) Instrumentation, measurement, and metrology : Reflection
  • (290.1483) Scattering : BSDF, BRDF, and BTDF
  • (280.4788) Remote sensing and sensors : Optical sensing and sensors

Balancing Polarization Aberrations in Crossed Fold Mirrors

  • Wai-sze Tiffany Lam and Russell Chipman
  • received 12/15/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 230735
  • [full text: PDF (1276) KB)]
  • Abstract: The polarization aberrations of a fold mirror can be compensated by orienting a second fold mirror’s p-polarization with the first mirror’s s-polarization. This crossed mirror configuration compensates the polarization for a single angle to zero and leaves a linear variation of diattenuation and retardance for a spherical wavefront. Two sets of crossed fold mirrors when properly oriented compensate the remaining linear variation and leaving a much reduced quadratic variation in a large compensated field of view.

Keywords (OCIS):

  • (080.1010) Geometric optics : Aberrations (global)
  • (260.5430) Physical optics : Polarization
  • (310.3915) Thin films : Metallic, opaque, and absorbing coatings
  • (310.5448) Thin films : Polarization, other optical properties

An optical design method for minimization of ghost stray light intensity

  • Semen Grabarnik
  • received 11/26/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 228581
  • [full text: PDF (1488) KB)]
  • Abstract: A method for minimization of intensity of ghost stray light during the optical design process is presented in this article. Dimensions of ghost images formed in an optical system can be estimated using an analytical algorithm. This algorithm enables construction of a merit function in an optical design software which depends on the dimensions and, consequently, on the intensity of ghost images. In this way, an optical system can be optimized for the best image quality and for the minimum ghosts intensity simultaneously. The proposed method has been applied to re – optimize a diffraction limited system of four lenses, and a reduction of ghost stray light by a factor of 6 with almost no degradation of image quality has been achieved.

Keywords (OCIS):

  • (220.2740) Optical design and fabrication : Geometric optical design
  • (220.3620) Optical design and fabrication : Lens system design
  • (290.2648) Scattering : Stray light
  • (290.2745) Scattering : Ghost reflections

Optical design of a LED lamp for a lighthouse of maritime signaling

  • Paola Sansoni, David Jafrancesco, Luca Mercatelli, Daniela Fontani, Elisa Sani, Stefano Coraggia, Marco Meucci, and Franco Francini
  • received 09/24/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 223749
  • [full text: PDF (897) KB)]
  • Abstract: Traffic signaling is emerging as a profitable application field for Light Emitting Diode lighting. This sustainable power-saving illumination technology can be used in maritime signalling thanks to the recently updated norms. Hence a LED-based lamp was optically designed for an authentic marine lighthouse to substitute traditional lamps. This source recombines multiple separated LEDs realizing a quasi-punctual localized source. Advantages are lower energy consumption, higher efficiency, longer life, less faults, slower aging and minor maintenance costs. The LED-based lighthouse is more durable and reliable. Usual high-consuming short-life lamps could be replaced with power-saving long-life LED lamps in many signaling systems.

Keywords (OCIS):

  • (120.5240) Instrumentation, measurement, and metrology : Photometry
  • (220.0220) Optical design and fabrication : Optical design and fabrication
  • (230.3670) Optical devices : Light-emitting diodes
  • (080.4298) Geometric optics : Nonimaging optics

The imaging and image restoration of on-axis three-mirror Cassegrain system with wavefront coding technology

  • Xiaohu Guo, Yuejin Zhao, Wei Jia, Lingqin Kong, Liquan Dong, Yijian Wu, and Bing Li
  • received 10/30/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 225970
  • [full text: PDF (2979) KB)]
  • Abstract: Wavefront coding (WFC) technology is adopted in the space optical system to resolve the problem of defocus by temperature difference or vibration of satellite motion. According to the theory of WFC, we calculate and optimize the phase mask parameter of the cubic phase mask plate which is used in an on-axis three-mirror Cassegrain (TMC) telescope system. The simulation analysis and the experimental results present that the defocused modulation transfer function (MTF) curves and the corresponding blurred images have a perfect consistency in the range of ten times depth of focus (DOF) of the original TMC system. After digital image processing by Wiener filter, the spatial resolution of the restored images is up to 57.14lp/mm. The results demonstrate that the WFC technology in TMC system has superior performance in extending the DOF and less sensitivity to defocus, which has high value in resolving the problem of defocus in the space optical system.

Keywords (OCIS):

  • (100.2000) Image processing : Digital image processing
  • (110.4100) Imaging systems : Modulation transfer function
  • (080.4035) Geometric optics : Mirror system design
  • (110.7348) Imaging systems : Wavefront encoding

(ISSR2014) Effective speckle noise suppression in OCT images using non-local means denoising filter with double Gaussian anisotropic kernels

  • Jichai Jeong, Jaehong Aum, and Ji-hyun Kim
  • received 11/04/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 226282
  • [full text: PDF (10235) KB)]
  • Abstract: Non-local means (NLM) filter is one of the state-of-the-art denoising filters. It exploits the presence of similar features in an image and averages those similar features to remove noise. However, conventional NLM filter shows somewhat inferior performance of noise reduction around edges, suffering from low efficiency of collecting similar features to be averaged. In order to overcome this phenomenon, we propose a NLM filter with double Gaussian anisotropic kernels as a substitute for the conventional homogeneous kernel to effectively remove noise from OCT images corrupted by speckle noise. The proposed filter was evaluated by comparing with various denoising filters such as conventional NLM filter, median filter, bilateral filter, and Wiener filter. The fingertip OCT images, which were processed with the different denoising filters, indicated that the proposed NLM filter provides superior denoising performance, among the filters in terms of the contrast-to-noise ratio (CNR), the equivalent number of looks (ENL), and the speckle suppression index (SSI). In addition, the denoising performance with the proposed NLM filter was also investigated in the synthetic images for fair comparison among the filters by calculating the peak signal-to-noise ratio (PSNR). The proposed NLM filter outperformed the conventional NLM filter as well as the other filters.

Keywords (OCIS):

  • (030.6140) Coherence and statistical optics : Speckle
  • (100.2980) Image processing : Image enhancement
  • (110.4280) Imaging systems : Noise in imaging systems
  • (110.4500) Imaging systems : Optical coherence tomography

Effect of Scattering Angle Error on Particle Size Determination by Multi-angle Dynamic Light Scattering

  • Jin Shen, gao shanshan, John Thomas, zuo yin, Wei Liu, wang yajing, Xianming Sun, and Xuemin Wang
  • received 11/06/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 226359
  • [full text: PDF (573) KB)]
  • Abstract: Dynamic light scattering (DLS) is a popular method of particle size measurement. Multi-angle dynamic light scattering (MDLS) collects DLS data at multiple angles and analyzes the data simultaneously to improve the particle size measurement. Using data from several scattering angles admits the possibility of introducing noise caused by scattering angle error in the measurement and this may impact the performance of the MDLS technique. We investigate the effect of scattering angle noise on recovered particle size distributions (PSDs) using simulated and measured MDLS data and various levels of angular noise. Our results show that, for unimodal PSDs, those with small particle sizes are more strongly affected by the noise than medium and large particle size systems. For bimodal PSDs, those containing small sized particles are also more affected by the noise than the systems of larger particles. Furthermore, broad PSDs are more vulnerable to angular noise than narrow PSDs.

Keywords (OCIS):

  • (120.5820) Instrumentation, measurement, and metrology : Scattering measurements
  • (290.0290) Scattering : Scattering
  • (290.3700) Scattering : Linewidth
  • (290.4020) Scattering : Mie theory

On the flow and thermal characteristics of high Reynolds number (2800-17000) dye cell: simulation and experiment

  • Govind Mishra, Abhay Kumar, Om Prakash, Ramakanta Biswal, Sudhir Dixit, and Shankar Nakhe
  • received 11/06/2014; accepted 03/02/2015; posted 03/03/2015; Doc. ID 226400
  • [full text: PDF (842) KB)]
  • Abstract: This paper presents computational and experimental studies on wavelength/frequency fluctuation characteristics of high pulse repetition rate (PRR: 18 kHz) dye laser pumped by frequency doubled Nd:YAG laser (532 nm). The temperature gradient in the dye solution is found to be responsible for wavelength fluctuations of the dye laser at low flow rates (2800 < Red < 5600). The turbulence Reynolds number (ReT) and the range of eddy sizes present in the turbulent flow are found to be responsible for the fluctuations at high flow rates (8400 < Red < 17000). A new dimensionless parameter, dimensionless eddy size (l+), has been defined to correlate the range of eddy sizes with the experimentally observed wavelength fluctuations. It was found that fluctuations can be controlled by keeping ReT~10 and l+max~1. The simulated result explains the experimental observation and provides a basis for designing the dye cells for high PRR pumping.

Keywords (OCIS):

  • (140.2050) Lasers and laser optics : Dye lasers
  • (140.3600) Lasers and laser optics : Lasers, tunable
  • (140.7300) Lasers and laser optics : Visible lasers

Enhancement of the perceived image quality of a 2D/3D convertible directional backlight unit system using a double slit barrier and an active diffuser

  • Hee-Jin Choi, Minyoung Park, Seihyoung Lee, and Byung-Tak Lee
  • received 12/04/2014; accepted 03/01/2015; posted 03/02/2015; Doc. ID 228793
  • [full text: PDF (3188) KB)]
  • Abstract: In this paper, a method to construct a directional-backlight unit system to separate the left-eye image and the right-eye image by adopting a double slit barrier array is proposed to enhance the perceived quality of the realized 3D image. Additionally, the two-dimensional/three-dimensional convertible function is also realized by adopting an active diffuser to the spatial interlacing directional-backlight system.

Keywords (OCIS):

  • (100.6890) Image processing : Three-dimensional image processing
  • (110.0110) Imaging systems : Imaging systems
  • (110.2990) Imaging systems : Image formation theory

Compact and rotationally invariant design of angle polished optical fiber assembly emitting along the mechanical axis

  • Garry Berkovic, David Rubin, Yair Saadi, and Ehud Shafir
  • received 01/28/2015; accepted 03/01/2015; posted 03/03/2015; Doc. ID 233316
  • [full text: PDF (457) KB)]
  • Abstract: This note describes a miniature assembly for optical fiber tips that ensures both ultra-low back reflection and an on-axis light beam exiting the fiber, resulting in a rigid, high performance and compact component combined with ease of assembly.

Keywords (OCIS):

  • (060.2310) Fiber optics and optical communications : Fiber optics
  • (060.2340) Fiber optics and optical communications : Fiber optics components
  • (220.2740) Optical design and fabrication : Geometric optical design


Implementation of the photonic time stretch concept using an incoherent pulsed light source

  • Bo Li, shuqin lou, and Jose Azana
  • received 12/17/2014; accepted 02/28/2015; posted 03/02/2015; Doc. ID 230808
  • [full text: PDF (1660) KB)]
  • Abstract: We propose a new technique to realize photonic time stretch of radio-frequency (RF) signals by using a time-gated (pulsed) incoherent light source. The proposed system provides similar performance specifications (stretch factor, temporal aperture and resolution) to those of a conventional coherent system but using a temporal gating process that is significantly longer than the transform-limited pulse duration of the equivalent coherent configuration. We experimentally demonstrate temporal magnification and compression of high-speed RF signals, with time-stretch factors ranging from 0.65 to 8.66, using a broadband (11.6-nm) incoherent light source temporally gated over ~163 ps. In one of the reported experiments, we achieve a resolution of ~67.5 ps over a temporal aperture of ~23 ns, representing a time-bandwidth product (TBP) of > 340.

Keywords (OCIS):

  • (070.1170) Fourier optics and signal processing : Analog optical signal processing
  • (250.4745) Optoelectronics : Optical processing devices
  • (320.7085) Ultrafast optics : Ultrafast information processing

Articles 1 to 20 of 164 Next Page >>

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