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July


Determining the topological charge of stochastic electromagnetic vortex beams with the degree of cross-polarization

  • Daomu Zhao and Meilan Luo
  • received 07/01/2014; accepted 07/22/2014; posted 07/25/2014; Doc. ID 215132
  • [full text: PDF (763) KB)]
  • Abstract: By analysis of the degree of cross-polarization of a stochastic electromagnetic vortex beam, it is found that the number of bright ring dislocations of which is equal to the topological charge of the vortex beam. Based on this property, we suggest a method to access the measurement of the orbital angular momentum of vector vortex beams, which holds true for cases of high coherence or low coherence.

Keywords (OCIS):

  • (030.1640) Coherence and statistical optics : Coherence
  • (260.0260) Physical optics : Physical optics
  • (260.5430) Physical optics : Polarization
  • (050.4865) Diffraction and gratings : Optical vortices

Ultrasensitive refractive index sensor based on Mach-Zehnder interferometer created in twin-core fiber

  • Yiping Wang, Zhengyong Li, Changrui Liao, Dong Xiaopeng, Shen Liu, Kaiming Yang, Qiao Wang, and Jiangtao Zhou
  • received 05/29/2014; accepted 07/21/2014; posted 07/21/2014; Doc. ID 212897
  • [full text: PDF (1222) KB)]
  • Abstract: We proposed and experimentally demonstrated a twin-core fiber based Mach-Zehnder interferometer to develop an ultrasensitive refractive index sensor. This fiber Mach-Zehnder interferometer was constructed by splicing a short section of twin-core fiber between two sections of single mode fibers. A micro-channel was drilled through one core of the twin-core fiber by means of femtosecond laser micromachining in order to create one arm of the proposed interferometer, and the other core worked as the second arm. Such a fiber interferometer exhibits an ultrahigh refractive index sensitivity of -10981nm/RIU and a low temperature cross-sensitivity of 3.96 ×10-6 RIU/°C. Moreover, the ultra-compact device size and all-fiber configuration make it very suitable for highly sensitive refractive index sensing at precise location.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (140.3390) Lasers and laser optics : Laser materials processing
  • (140.3948) Lasers and laser optics : Microcavity devices

Photonic downconversion based on optical carrier bidirectional reusing in a phase modulator

  • Tianwei Jiang, Song Yu, qian xie, Wanyi Gu, and Jian Li
  • received 06/03/2014; accepted 07/21/2014; posted 07/21/2014; Doc. ID 213324
  • [full text: PDF (422) KB)]
  • Abstract: We propose a novel photonic downconversion method based on optical carrier reusing. In the system, PM is placed between two narrow-band fiber Bragg gratings (FBGs), which are designed to reflect the optical carrier and transmit the optical sidebands. The optical carrier is modulated in the PM in two directions and is not injected into the photodetector (PD). Thus, the utilization ratio of optical carrier is enhanced and the power saturation in PD is avoided. Consequently, the system gain can be improved. In addition, a 2 × 2 optical coupler is cooperated with a balance photodetector behind the two FBGs. Resulting from the subtle design of the phase difference, gain is furthermore doubled and intensity noise can be reduced simultaneously. In the experiments, 29 dB gain improvement is measured compared with the traditional dual-series intensity modulators method. Noise floor is reduced by 12.1 dB.

Keywords (OCIS):

  • (060.5060) Fiber optics and optical communications : Phase modulation
  • (060.3735) Fiber optics and optical communications : Fiber Bragg gratings
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics

High resolution imaging and wavefront aberration correction in plenoptic systems

  • Juan Trujillo, Iciar Montilla, Luis Fernando Ramos, and José Rodríguez-Ramos
  • received 06/10/2014; accepted 07/21/2014; posted 07/21/2014; Doc. ID 213857
  • [full text: PDF (1338) KB)]
  • Abstract: Plenoptic imaging systems are becoming more common since they provide capabilities unattainable in conventional imaging systems, but one of their main limitations is the poor bidimensional resolution. Combining the wavefront phase measurement and the plenoptic image deconvolution, we propose a system capable of improving the resolution when a wavefront aberration is present and the image is blurred. In this work, a plenoptic system is simulated using Fourier optics, and the results show that an improved resolution is achieved, even in presence of strong wavefront aberrations.

Keywords (OCIS):

  • (100.1830) Image processing : Deconvolution
  • (120.5050) Instrumentation, measurement, and metrology : Phase measurement
  • (110.0115) Imaging systems : Imaging through turbulent media

Continuous wave Pr3+:BaY2F8 and Pr3+:LiYF4 lasers in the cyan-blue spectral region

  • Philip Metz, Kore Hasse, Daniela Parisi, Nils-Owe Hansen, Christian Kraenkel, Mauro Tonelli, and Guenter Huber
  • received 06/25/2014; accepted 07/21/2014; posted 07/21/2014; Doc. ID 214793
  • [full text: PDF (639) KB)]
  • Abstract: We report on the first continuous wave quasi 3-level lasers emitting in the cyan-blue spectral range in praseodymium doped crystalline materials. Applying Pr3+:BaY2F8 as active medium, up to 201 mW of output power at 495 nm could be obtained with a slope efficiency of 27% under pumping with an optically pumped semiconductor laser (2ω-OPSL) at 480 nm. In the same pumping scheme, utilizing Pr3+:LiYF4 output powers up to 70 mW were realized at 491 nm and 500 nm, respectively. With Pr3+:BaY2F8 also diode pumped laser operation with up to 11% slope efficiency and 44 mW output power was achieved. In the latter case, detailed investigations on the temperature dependency of the laser output were conducted. Moreover, comparative experiments were carried out for the first time with green emitting Pr3+:BaY2F8 lasers at 524 nm and 553 nm both under diode and 2ω-OPSL excitation

Keywords (OCIS):

  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.7300) Lasers and laser optics : Visible lasers

Digital holography at light levels below noise using photon-counting approach

  • Nazif Demoli, Hrvoje Skenderovic, and Mario Stipcevic
  • received 06/09/2014; accepted 07/21/2014; posted 07/22/2014; Doc. ID 213778
  • [full text: PDF (765) KB)]
  • Abstract: Recording of digital holograms of a weak signal (0.44 counts per second (cps)) hidden below the detector's noise (21 cps) is investigated by employing high dynamic range of a photon-counting detector. Recording conditions are discussed in terms of the most important holographic measures, namely the fringe visibility (or contrast) and signal-to-noise ratio, and in relation to the main holographic parameters. Theoretically evaluated curves are tested by recording holograms for a wide range of the parameter values. We found that (i) optimum set of holographic parameters can be determined for a harsh signal conditions, (ii) increasing the visibility does not necessarily improve the more important signal-to-noise ratio, and (iii) in cases of nearly constant visibility the signal-to-noise ratio clearly reveals differences in the quality of holographic recordings.

Keywords (OCIS):

  • (030.5260) Coherence and statistical optics : Photon counting
  • (090.0090) Holography : Holography
  • (100.2650) Image processing : Fringe analysis
  • (090.1995) Holography : Digital holography

Absorption Enhancement of Molecules in the Weak Plasmon-Exciton Coupling Regime

  • Atilla Aydinli, Ertugrul Karademir, SINAN BALCI, and Coskun Kocabas
  • received 07/04/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 216389
  • [full text: PDF (940) KB)]
  • Abstract: We report on the experimental and theoretical investigations of enhancement of optical absorption of organic molecules in the weak plasmon-exciton coupling regime. A metal-organic hybrid structure consisting of dye molecules embedded in the polymer matrix is placed in close vicinity to thin metal films. We have observed a transition from weak-coupling regime to strong-coupling regime as the thickness of the metal layer increases. The results indicate that absorption of the self-assembled J-aggregate nanostructures can be increased in the weak plasmon-exciton coupling regime and strongly quenched in the strong-coupling regime. Theoretical model based on transfer matrix method qualitatively confirms the experimental results obtained from polarization dependent spectroscopic reflection measurements.

Keywords (OCIS):

  • (160.2540) Materials : Fluorescent and luminescent materials
  • (240.0240) Optics at surfaces : Optics at surfaces
  • (240.5420) Optics at surfaces : Polaritons
  • (240.6680) Optics at surfaces : Surface plasmons
  • (250.5403) Optoelectronics : Plasmonics

Controlling high power autofocusing waves with periodic lattices

  • Paris Panagiotopoulos, Dimitris Papazoglou, Stelios Tzortzakis, and Arnaud Couairon
  • received 06/19/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 214241
  • [full text: PDF (1333) KB)]
  • Abstract: We show numerically that by using radial symmetric lattices, the focal spot characteristics and filament peak intensity of high power autofocusing waves can be controlled. The lattice induced diffraction is able to isolate the main on-axis peak and control the focus position. In addition, at higher power the lattice is able to control and stabilize the peak intensity of the filament over an extended distance.

Keywords (OCIS):

  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (190.0190) Nonlinear optics : Nonlinear optics
  • (320.7110) Ultrafast optics : Ultrafast nonlinear optics

Catoptric electrodes: fully transparent metal electrodes using shaped surfaces

  • Pieter Kik
  • received 04/01/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 209337
  • [full text: PDF (949) KB)]
  • Abstract: An optical electrode design is presented that theoretically allows 100% optical transmission through an interdigitated metallic electrode at 50% metal areal coverage. This is achieved by redirection of light incident on embedded metal electrode lines to an angle beyond that required for total internal reflection. Full-field electromagnetic simulations using realistic material parameters demonstrate 84% frequency-averaged transmission for unpolarized illumination across the entire visible spectral range using a silver interdigitated electrode at 50% areal coverage. The redirection is achieved through specular reflection, making it non-resonant and arbitrarily broadband, provided the electrode width exceeds the optical wavelength. These findings could significantly improve the performance of photovoltaic devices and optical detectors that require high-conductivity top contacts.

Keywords (OCIS):

  • (040.5160) Detectors : Photodetectors
  • (240.6680) Optics at surfaces : Surface plasmons
  • (310.7005) Thin films : Transparent conductive coatings

A polarization diversified photonic comb filter with independently tunable free spectrum range

  • Lianshan Yan, Hengyun Jiang, Jia Ye, Wei Pan, Bing Luo, and Xihua Zou
  • received 04/08/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 209706
  • [full text: PDF (414) KB)]
  • Abstract: A polarization diversified photonic comb filter with tunable free spectrum range (FSR) is proposed using two variable DGD elements in a loop configuration. Two different cosine transfer functions could be simultaneously realized on orthogonal polarization states. Experimental demonstrations also verify feasibilities in various reconfigurable transfer functions.

Keywords (OCIS):

  • (060.2340) Fiber optics and optical communications : Fiber optics components
  • (120.2440) Instrumentation, measurement, and metrology : Filters
  • (230.0230) Optical devices : Optical devices

Broadband electro-optical modulator based on transparent conducting oxide

  • Kaifeng Shi, Zhaolin Lu, Riaz Haque, Runchen Zhao, and Bingyin Zhao
  • received 04/17/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 210008
  • [full text: PDF (613) KB)]
  • Abstract: We report a broadband electro-optical modulator based on tunable plasmonic metamaterials. Transparent conducting oxides provide excellent active plasmonic material for optoelectronic applications. By utilizing our indium tin oxide (ITO)-based multi-layer structure, light absorption of the active ITO layer can be electrically modulated over a large spectrum range. Based on the attenuated total reflectance configuration, bias polarity-dependent modulation up to 37% has been experimentally demonstrated. This electro-optical modulator has advantages of simple design, easy fabrication, compact size, broadband performance, large modulation depth, as well as compatibility with existing silicon photonics platforms, which may serve as potential solution for future optical interconnects.

Keywords (OCIS):

  • (160.2100) Materials : Electro-optical materials
  • (230.2090) Optical devices : Electro-optical devices
  • (250.4110) Optoelectronics : Modulators

Experimental observation of lateral emission in freestanding GaN-based membrane devices

  • yongjin wang, Zheng Shi, Xin Li, Xiaojing Fang, Xiaoming Huang, and Hongbo Zhu
  • received 05/07/2014; accepted 07/20/2014; posted 07/21/2014; Doc. ID 211570
  • [full text: PDF (1350) KB)]
  • Abstract: This paper describes a double-side process to fabricate freestanding membrane devices on a GaN-on-silicon platform. The photoluminescence (PL) measurement is conducted to characterize the optical performance. A large portion of the excited light from InGaN/GaN multiple quantum wells (MQWs) is trapped as waveguide modes and propagates with different directions. Experimental results show that the propagation direction of the waveguide mode can be converted into the direction normal to the surface at the edge of freestanding membrane, and the emitted light is attenuated due to light propagation loss before it gets out from the edge. Subwavelength grating can also convert waveguide modes into air modes on freestanding membrane. These results suggest that the emission efficiency can be greatly improved by employing more efficient light extraction methods and GaN-based photonic waveguide are promising in the visible range.

Keywords (OCIS):

  • (250.5230) Optoelectronics : Photoluminescence
  • (220.4241) Optical design and fabrication : Nanostructure fabrication
  • (310.6628) Thin films : Subwavelength structures, nanostructures

Ultra-long pure longitudinal magnetization needle induced by annular vortex binary optics

  • Min Gu, SICONG WANG, Xiangping Li, and Jianying Zhou
  • received 06/16/2014; accepted 07/19/2014; posted 07/25/2014; Doc. ID 213830
  • [full text: PDF (2073) KB)]
  • Abstract: In this Letter based on the vectorial Debye diffraction theory an ultra-long optical needle with pure transverse polarization is numerically generated by tightly focusing an azimuthally polarized beam through an annular vortex binary filter. Such an ultra-long transversely polarized optical needle is generated through the π phase shift between adjacent rings of the binary filter. We show that such a pure transverse optical needle can induce pure longitudinal magnetization with a sub-wavelength lateral size (0.38λ) and an ultra-long longitudinal depth (7.48λ) through the inverse Faraday effect. The corresponding needle aspect ratio of 20 is twice as large as that of the longitudinal magnetization needle generated by electron beam lithography

Keywords (OCIS):

  • (050.1380) Diffraction and gratings : Binary optics
  • (160.3820) Materials : Magneto-optical materials
  • (260.5430) Physical optics : Polarization

Near orthogonal launch of SPR modes in Au films

  • John Canning, Akib Karim, Nikki Tzoumis, Yanzhen Tan, Rodolfo Patyk, and Brant Gibson
  • received 03/14/2014; accepted 07/18/2014; posted 07/18/2014; Doc. ID 208258
  • [full text: PDF (1218) KB)]
  • Abstract: We report the excitation of a surface plasmon resonance (SPR) close to the orthogonal axis of a gold (Au) film on borosilicate glass. Direct spectroscopic measurement of SPR shifts using different liquids are made at ~5° incidence within a reflection spectrophotometer. Scattering of light that is able to penetrate across the film at the interfaces is the proposed mechanism by which coupling, and plasmon localization, is established.

Keywords (OCIS):

  • (160.3900) Materials : Metals
  • (240.5420) Optics at surfaces : Polaritons
  • (240.5770) Optics at surfaces : Roughness
  • (240.6680) Optics at surfaces : Surface plasmons
  • (240.6690) Optics at surfaces : Surface waves
  • (160.4236) Materials : Nanomaterials

High power flip chip semiconductor disk laser in the 1.3 µm wavelength band

  • Antti Rantamäki, Alexei Sirbu, Alexandru Mereuta, Vladimir Iakovlev, Eli Kapon, Esa Saarinen, Jari Lyytikäinen, and Oleg Okhotnikov
  • received 05/22/2014; accepted 07/18/2014; posted 07/18/2014; Doc. ID 212569
  • [full text: PDF (1848) KB)]
  • Abstract: We present 6.1 W of output power from a flip chip semiconductor disk laser emitting in the 1.3 µm wavelength region. This is the first demonstration of a flip chip semiconductor disk laser in this wavelength range with output powers that are comparable to those obtained with intracavity diamond heat spreaders. The flip chip configuration circumvents the optical distortions and losses that the intracavity diamond heat spreaders can introduce into the laser cavity. This is essential for several key applications of semiconductor disk lasers.

Keywords (OCIS):

  • (140.3480) Lasers and laser optics : Lasers, diode-pumped
  • (140.5960) Lasers and laser optics : Semiconductor lasers
  • (140.7270) Lasers and laser optics : Vertical emitting lasers

Multilayer plasmonic vortex lenses for the efficient generation of angular momentum light states at the nanoscale

  • Pierfrancesco Zilio, Giuseppe Parisi, Denis Garoli, Marta Carli, and Filippo Romanato
  • received 06/11/2014; accepted 07/18/2014; posted 07/18/2014; Doc. ID 213922
  • [full text: PDF (948) KB)]
  • Abstract: We report the design of a new holey plasmonic vortex lens (PVL) structure able to couple circularly polarized impinging light to a plasmonic vortex in the form of the fundamental TM mode of a metal-insulator-metal plasmonic waveguide. The field transmitted through the hole milled at the center of the second metal layer of the structure is characterized by a well-defined spiral harmonic, entirely determined by the spin of impinging light and by the chirality of the PVL structure. Scattering finite elements simulations are presented for single layer standard PVLs and for multilayer ones, comparing the spiral spectra of the transmitted field and the efficiencies of the architectures.

Keywords (OCIS):

  • (240.6680) Optics at surfaces : Surface plasmons
  • (080.4865) Geometric optics : Optical vortices
  • (250.5403) Optoelectronics : Plasmonics
  • (260.6042) Physical optics : Singular optics
  • (130.5440) Integrated optics : Polarization-selective devices

Narsarsukite-structure fluorosilicate as a blue component for white LEDs: structural and optical properties

  • Won Bin Im and Yoon Hwa Kim
  • received 06/23/2014; accepted 07/18/2014; posted 07/18/2014; Doc. ID 214539
  • [full text: PDF (1575) KB)]
  • Abstract: A new blue-emitting phosphor, K2ScSi4O10F:Eu2+ (KSSOF:Eu2+), was synthesized through a solid-state reaction. The structural and optical properties of KSSOF:Eu2+ phosphor, in addition to its thermal quenching and fabrication of white LED were investigated for the first time. The phosphor showed broad blue emission, with a maximum at ~434 nm under near-UV excitation due to 5d→4f transition of the Eu2+ ion. The critical distance was calculated to be 12 Å using the critical concentration of Eu2+ and Dexter’s theory for energy transfer. White LEDs were fabricated by blending KSSOF:Eu2+, commercial Lu3Al5O12:Ce3+, and (Sr,Ca)AlSiN3:Eu2+ phosphor, showed high color rendering index of 88 at correlated color temperature of 4134 K under forward bias current of 100 mA.

Keywords (OCIS):

  • (160.5690) Materials : Rare-earth-doped materials
  • (230.3670) Optical devices : Light-emitting diodes
  • (250.5230) Optoelectronics : Photoluminescence
  • (260.3800) Physical optics : Luminescence
  • (300.1030) Spectroscopy : Absorption
  • (300.2140) Spectroscopy : Emission

Mid-infrared frequency comb for broadband high precision and sensitivity molecular spectroscopy

  • Francesco Cappelli, Iacopo Galli, Davide Mazzotti, Giovanni Giusfredi, Naota Akikusa, Masamichi Yamanishi, Paolo De Natale, Saverio Bartalini, and Pablo Cancio Pastor
  • received 06/06/2014; accepted 07/17/2014; posted 07/17/2014; Doc. ID 213106
  • [full text: PDF (422) KB)]
  • Abstract: We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a non-linear down-conversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multi-frequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Pérot cavity.

Keywords (OCIS):

  • (120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
  • (140.3590) Lasers and laser optics : Lasers, titanium
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (190.4223) Nonlinear optics : Nonlinear wave mixing
  • (140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade

Precise frequency measurement and characterization of a continuous scanning single-mode laser with an optical frequency comb

  • Masatoshi Misono, Akiko Nishiyama, and Ayumi Matsuba
  • received 06/27/2014; accepted 07/17/2014; posted 07/17/2014; Doc. ID 214345
  • [full text: PDF (525) KB)]
  • Abstract: We developed a high-precision frequency measurement system for continuously scanning single-mode continuous-wave (cw) lasers. The high precision for wide frequency range is realized by employing an optical frequency comb. The developed system operates as a strong tool for analyzing the spectral profile and scan characteristics of lasers, which is suitable for high-resolution molecular spectroscopy. We demonstrated the ability of our system with Doppler-free spectroscopy of molecular iodine.

Keywords (OCIS):

  • (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (300.6320) Spectroscopy : Spectroscopy, high-resolution
  • (300.6390) Spectroscopy : Spectroscopy, molecular

All-optical modulation and switching by a metamaterial of plasmonic circuits

  • Timothy Davis, Daniel Gomez, and fatima eftekhari
  • received 06/30/2014; accepted 07/17/2014; posted 07/21/2014; Doc. ID 214598
  • [full text: PDF (1050) KB)]
  • Abstract: We demonstrate experimentally the modulation and switching of one light beam by a second beam using metamaterials constructed from arrays of plasmonic circuits. Each circuit consist of three gold nanorods that mix together two coherent but orthogonally polarized light beams leading to modulation by an interference effect. By adjusting the phase and the amplitude of one of the beams, the amplitude and spectral composition of the second beam is altered. The plasmonic circuits display an asymmetry that enables an angle-dependent modulation, which we demonstrate with a diffraction grating where the energy directed into two diffraction orders is controlled by a second light beam. This effect appears like an optically-controlled blaze that we use to switch a light beam between two different directions.

Keywords (OCIS):

  • (230.1150) Optical devices : All-optical devices
  • (230.1950) Optical devices : Diffraction gratings
  • (230.4110) Optical devices : Modulators
  • (250.5403) Optoelectronics : Plasmonics
  • (050.6624) Diffraction and gratings : Subwavelength structures

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