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Articles 1 to 20 of 126 Next Page >>

April


High Power Beam Transport through Hollow Core Photonic Bandgap Fiber

  • Charlotte Bennett, David Jones, Mark Smith, and Andrew Scott
  • received 03/17/2014; accepted 04/18/2014; posted 04/18/2014; Doc. ID 206754
  • [full text: PDF (430) KB)]
  • Abstract: We investigate the use of 7-cell hollow core photonic band-gap fiber for transport of CW laser radiation from a single-mode narrow-linewidth high-power fiber laser amplifier. Over 90% of the amplifier output was successfully coupled and transmitted through the fiber in a near-Gaussian mode with negligible back-reflection into the source. 100 W of power was successfully transmitted continuously without damage and 160 W of power was transmitted briefly before the onset of thermal lensing in the coupling optics.

Keywords (OCIS):

  • (060.2270) Fiber optics and optical communications : Fiber characterization
  • (140.3325) Lasers and laser optics : Laser coupling
  • (060.4005) Fiber optics and optical communications : Microstructured fibers

Second-harmonic generation in AlGaAs microdisks in the telecom range

  • Giuseppe Leo, Silvia Mariani, Alessio Andronico, Aristide Lemaitre, Ivan Favero, and Sara Ducci
  • received 02/24/2014; accepted 04/18/2014; posted 04/18/2014; Doc. ID 207009
  • [full text: PDF (956) KB)]
  • Abstract: We report on second-harmonic generation in whispering-gallery-mode AlGaAs microcavities suspended on a GaAs pedestal. Frequency doubling of a 1.58 μm pump is observed with 7×10-4 W−1 conversion efficiency. This device can be integrated in a monolithic photonic chip for applications in the telecom band.

Keywords (OCIS):

  • (130.5990) Integrated optics : Semiconductors
  • (140.3945) Lasers and laser optics : Microcavities
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Enhanced broadband excited upconversion luminescence in Ho-doped glasses by codoping with bismuth

  • bei Xu, Gongxun Bai, Juechen Wang, Qiangbing Guo, Weibo Chen, Xiaofeng Liu, shifeng zhou, Jianhua Hao, Jianrong Qiu, and Dezhi Tan
  • received 02/19/2014; accepted 04/17/2014; posted 04/18/2014; Doc. ID 206775
  • [full text: PDF (662) KB)]
  • Abstract: We report greatly enhanced green and red upconversion luminescence in Ho3+-doped oxyfluoride germanate glass by introducing bismuth near-infrared active centers as sensitizers. The upconversion excitation bands at 750 and 970 nm show a full width at half maximum of 20 and 45 nm, respectively. Energy transfer from sensitizers, the excited-state absorption, and phonon-coupled absorption of Ho3+ jointly contribute to the enhanced upconversion luminescence. Our approach provides an efficient methodology to broaden the excitation bandwidth of upconversion luminescent materials, which may have promising application in solar cells.

Keywords (OCIS):

  • (040.5350) Detectors : Photovoltaic
  • (160.2540) Materials : Fluorescent and luminescent materials
  • (190.7220) Nonlinear optics : Upconversion

Optically controlled background-free terahertz switching in chiral metamaterial

  • Jin-hui Shi, tingting Lv, zheng zhu, Chunying Guan, Zhengping Wang, and Tie Jun Cui
  • received 02/21/2014; accepted 04/17/2014; posted 04/18/2014; Doc. ID 206887
  • [full text: PDF (1499) KB)]
  • Abstract: We demonstrate a multi-band background-free terahertz (THz) switch in photoactive chiral metamaterial using polarization conversion. Orthogonal arrangement of two asymmetrically split-ring apertures allows a high polarization conversion efficiency and low co-polarization transmission. The chiral metamaterial embedded with photoactive silicon promises a dynamic control on cross-polarization transmission and thus enables efficient background-free THz switch. The on/off state of THz metamaterial switching can be efficiently controlled by optical pump. The realization of cross-polarization THz switch provides a new mechanism of mode switching to control THz wave propagation and will be a promising candidate for polarization devices.

Keywords (OCIS):

  • (260.5150) Physical optics : Photoconductivity
  • (260.5430) Physical optics : Polarization
  • (160.1585) Materials : Chiral media
  • (160.3918) Materials : Metamaterials

Polymer optical microstructured fiber with birefringence induced by stress applying elements

  • Pawel Mergo, Tadeusz Martynkien, and Waclaw Urbanczyk
  • received 03/14/2014; accepted 04/17/2014; posted 04/17/2014; Doc. ID 208324
  • [full text: PDF (1854) KB)]
  • Abstract: We report on the fabrication of a birefringent microstructured PMMA fiber with polystyrene stress applying elements located in the solid part of the cladding. A microstructured part of the cladding composed of three rings of holes was made of We report on the fabrication of a birefringent microstructured PMMA fiber with polystyrene stress applying elements located in the solid part of the cladding. A microstructured part of the cladding composed of three rings of holes was made of a technical grade PMMA by a drilling method. The fiber shows relatively high birefringence of the order of 4x10-5, which weakly depends upon wavelength in the investigated spectral range from 0.6 to 1μm. The cross-talk between polarization modes is lower than 20 dB for a 1m long fiber, while the fiber loss is about 8dB/m at 0.83μm. We also studied the fiber response to temperature in the range from 20 to 60 °C. The temperature induced birefringence change is negative and shows significant hysteresis in the first cycle which gradually disappears in successive cycles. a technical grade PMMA by a drilling method. The fiber shows relatively high birefringence of the order of 4x10-5, which weakly depends upon wavelength in the investigated spectral range from 0.6 to 1μm. The cross-talk between polarization modes is lower than 20 dB for a 1m long fiber, while the fiber loss is about 8dB/m at 0.83μm. We also studied the fiber response to temperature in the range from 20 to 60 °C. The temperature induced birefringence change is negative and shows significant hysteresis in the first cycle which gradually disappears in successive cycles.

Keywords (OCIS):

  • (060.2270) Fiber optics and optical communications : Fiber characterization
  • (060.2280) Fiber optics and optical communications : Fiber design and fabrication
  • (060.2420) Fiber optics and optical communications : Fibers, polarization-maintaining
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers
  • (130.5460) Integrated optics : Polymer waveguides

Robust and accurate transient light transport decomposition via convolutional sparse coding

  • Xuemei Hu, Qionghai Dai, Christopher Barsi, Xing Lin, Jinli Suo, Ramesh Raskar, and Deng Yue
  • received 01/16/2014; accepted 04/16/2014; posted 04/18/2014; Doc. ID 204602
  • [full text: PDF (2268) KB)]
  • Abstract: Ultrafast sources and detectors have been used to record the time-resolved scattering of light propagating through macroscopic scenes. In the context of computational imaging, decomposition of this transient light transport is useful for applications such as characterizing materials, imaging through diffuser layers, and relighting scenes dynamically. Here we demonstrate a method of convolutional sparse decomposition to decompose transient light transport into direct reflections, inter-reflections, and subsurface scattering. The method relies on the sparsity of the time-resolved kernel. We show that it is robust and accurate to noise during the acquisition process.

Keywords (OCIS):

  • (100.3190) Image processing : Inverse problems
  • (150.1135) Machine vision : Algorithms
  • (070.2025) Fourier optics and signal processing : Discrete optical signal processing

Self-Aligned Optical Couplings by Self-Organized Waveguides Toward Luminescent Targets in Organic/Inorganic Hybrid Materials

  • Tetsuzo Yoshimura, Hideyuki Nawata, and Makoto Iida
  • received 03/11/2014; accepted 04/16/2014; posted 04/18/2014; Doc. ID 207951
  • [full text: PDF (1482) KB)]
  • Abstract: Self-organization of optical waveguides is observed between two opposed optical fibers placed in a photosensitive organic/inorganic hybrid material, Sunconnect. A luminescent target containing coumarin 481 was deposited onto the edge of one of the two fibers at the core. When a 448-nm write beam was introduced from the other fiber, the write beam and the luminescence from the photoexcited target increased the refractive index of Sunconnect to induce self-focusing. Traces of waveguides were seen to grow from the cores of both fibers and merged into a single self-aligned optical coupling between the fibers. This optical solder functionality enabled increases in both coupling efficiency and tolerance to lateral misalignment of the fibers.

Keywords (OCIS):

  • (200.4650) Optics in computing : Optical interconnects
  • (260.5950) Physical optics : Self-focusing
  • (130.5460) Integrated optics : Polymer waveguides

Multi-mJ, kHz, 2.1-μm optical parametric chirped-pulse amplifier and high-flux soft X-ray high-harmonic generation

  • Kyung-Han Hong, FRANZ KAERTNER, Jeffrey Moses, Chien-Jen Lai, Luis Zapata, Peter Krogen, Jonathas Siqueira, Gregory Stein, and Chun-Lin Chang
  • received 03/13/2014; accepted 04/16/2014; posted 04/16/2014; Doc. ID 208176
  • [full text: PDF (569) KB)]
  • Abstract: We report on a multi-mJ 2.1-μm optical parametric chirped-pulse amplification (OPCPA) system operating at 1-kHz repetition rate, pumped by a picosecond cryogenic Yb:YAG laser, and the demonstration of soft X-ray high-harmonic generation (HHG) with a flux of ~2x10⁸ photon/s/1% bandwidth at 160 eV in Ar. The 1-kHz cryogenic Yb:YAG pump laser amplifies pulses up to 56 mJ and delivers compressed 42-mJ, 17- ps pulses to the 2.1-μm OPCPA system. In the 3-stage OPCPA chain, we have obtained up to 2.6 mJ of output energies at 2.1 μm and pulses compressed to 40 fs with good beam quality. Finally, we show cutoff extension of HHG driven by this 2.1 μm source in Ar and N₂ gas cells to 190 eV with high photon flux. Our 3-dimensional propagation simulation confirms the generation of soft X-ray attosecond pulses from the experiment with Ar.

Keywords (OCIS):

  • (190.4970) Nonlinear optics : Parametric oscillators and amplifiers
  • (320.7090) Ultrafast optics : Ultrafast lasers
  • (340.7480) X-ray optics : X-rays, soft x-rays, extreme ultraviolet (EUV)

Low-threshold optical bistabilities in ultra-thin plasmonic films

  • Lei Zhou, Shiwei Tang, baocheng Zhu, Shiyi Xiao, and Jung-Tsung Shen
  • received 03/26/2014; accepted 04/16/2014; posted 04/16/2014; Doc. ID 209003
  • [full text: PDF (1460) KB)]
  • Abstract: Optical bistability typically occurs only when the optical thickness in the device or the input light power is unfavorably large. Here we show that, for a class of plasmonic metamaterials consisting of ultra-thin holey metallic plates filled with nonlinear materials, the optical bistability can occur with an ultra-low excitation power. We present a realistic design working at 0.2 THz and perform full-wave simulations to quantitatively study its optical bistability properties. An analytical model is developed to explain the inherent physics and provides a general design guideline for future development.

Keywords (OCIS):

  • (190.0190) Nonlinear optics : Nonlinear optics
  • (310.0310) Thin films : Thin films
  • (160.3918) Materials : Metamaterials
  • (250.5403) Optoelectronics : Plasmonics

Er/Tm:fiber laser system for coherent Raman microscopy

  • Giulio Cerullo, Marco Marangoni, Nicola Coluccelli, Gianluca Galzerano, Marco Cassinerio, and Vikas Kumar
  • received 03/03/2014; accepted 04/16/2014; posted 04/17/2014; Doc. ID 206899
  • [full text: PDF (1018) KB)]
  • Abstract: We present a novel architecture for a fiber-based hybrid laser system for coherent Raman microscopy, combining an amplified Er:fiber femtosecond oscillator with a Tm:fiber amplifier boosting the power of the 2-µm portion of a supercontinuum up to 300 mW. This is enough to obtain, by means of nonlinear spectral compression, sub-20-cm^-1 wide pump and Stokes pulses with 2500-3300 cm^-1 frequency detuning and average power at the 100-mW level. Application of this system to stimulated Raman scattering microscopy is discussed.

Keywords (OCIS):

  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (190.5650) Nonlinear optics : Raman effect
  • (190.7110) Nonlinear optics : Ultrafast nonlinear optics
  • (320.5390) Ultrafast optics : Picosecond phenomena

Frequency-resolved optical gating with two nonlinear optical processes

  • Yuichiro Kida, Yuta Nakano, Kazuya Motoyoshi, and Totaro Imasaka
  • received 03/03/2014; accepted 04/16/2014; posted 04/17/2014; Doc. ID 207425
  • [full text: PDF (483) KB)]
  • Abstract: A frequency-resolved optical gating (FROG) technique that combines autocorrelation (second-harmonic-generation FROG, SHG-FROG) and cross-correlation FROG (XFROG) is reported for simultaneous characterization of two unknown optical pulses. Two SHG-FROG signals and a XFROG signal are acquired in a single measurement using a single diagnostic system. Unlike the conventional combination of SHG-FROG for reference-pulse characterization and XFROG for test-pulse characterization, the ambiguity in the direction of time in SHG-FROG is removed during phase retrieval by simultaneously analyzing the three FROG signals. Furthermore, over all characterization is faster, more robust, and highly convergent than the conventional combination of SHG-FROG and XFROG techniques.

Keywords (OCIS):

  • (320.7100) Ultrafast optics : Ultrafast measurements
  • (320.7160) Ultrafast optics : Ultrafast technology

High efficient 12W diode-pumped actively Q-switched Yb:KGd(WO4)2 laser

  • Alexander Rudenkov, Viktor Kisel, Anatoliy Pavlyuk, and Nikolai Kuleshov
  • received 03/14/2014; accepted 04/16/2014; posted 04/17/2014; Doc. ID 208227
  • [full text: PDF (1317) KB)]
  • Abstract: Compact diode-pumped actively Q-switched Yb:KGW laser is demonstrated with optical-to-optical efficiency of 50%. In a 3-mirror laser cavity configuration output power of 12.2 W with repetition rate up to 50 kHz and pulse duration of 10-24 ns was obtained. The maximum pulse peak power of 70 kW was achieved. The laser output beam profile was Gaussian up to maximum pump powers with M2 factor lower than 1.2.

Keywords (OCIS):

  • (140.3480) Lasers and laser optics : Lasers, diode-pumped
  • (140.3540) Lasers and laser optics : Lasers, Q-switched
  • (140.3615) Lasers and laser optics : Lasers, ytterbium

Diversity-Multiplexing Tradeoff in Mode-Division Multiplexing

  • Sercan Arik and Joseph Kahn
  • received 01/21/2014; accepted 04/16/2014; posted 04/16/2014; Doc. ID 205253
  • [full text: PDF (411) KB)]
  • Abstract: The capacity of mode-division multiplexing (MDM) systems is limited, for a given outage probability, by mode-dependent loss and gain. Modal degrees of freedom may be exploited to increase transmission rate (multiplexing gain) or lower outage probability (diversity gain), but there is a fundamental tradeoff between the achievable multiplexing and diversity gains. In this letter, we present the diversity-multiplexing tradeoff in MDM systems for the first time, studying the impact of signal-to-noise ratio, mode-dependent loss, and frequency diversity order on the tradeoff in the strong-mode-coupling regime.

Keywords (OCIS):

  • (060.0060) Fiber optics and optical communications : Fiber optics and optical communications
  • (060.1660) Fiber optics and optical communications : Coherent communications
  • (060.2330) Fiber optics and optical communications : Fiber optics communications
  • (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
  • (060.4080) Fiber optics and optical communications : Modulation
  • (060.4230) Fiber optics and optical communications : Multiplexing

Ultraviolet-to-visible down-conversion luminescence of Eu3+ ions in sol-gel silica containing GdF3 nanocrystals

  • Barbara Szpikowska-Sroka, Lidia Zur, Rozalia Czoik, Tomasz Goryczka, Maria Zadlo, and Wojciech Pisarski
  • received 02/07/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 206106
  • [full text: PDF (2112) KB)]
  • Abstract: GdF3 nanocrystals doped with Eu3+ ions with high emission efficiency were prepared by sol-gel method. The structural properties were examined by XRD measurements. The effects of gadolinium co-doping on europium emission in the prepared sol-gel glasses have been studied. The registered emission bands correspond to 5Do→7FJ (J=0-4) transitions of Eu3+. The electric dipole 5Do →7F2 transitions were dominant in the samples before heat treatment, whereas magnetic dipole 5Do → 7F1 transitions had a higher probability in the samples after annealing. The luminescence lifetime for the 5Do level of Eu3+ ions in the samples after excitation at 273 nm is long-lived in comparison to excitation at 393 nm and increased to 190%. Energy transfer from Gd3+ to Eu3+ was observed.

Keywords (OCIS):

  • (160.4670) Materials : Optical materials
  • (160.4760) Materials : Optical properties
  • (160.6060) Materials : Solgel
  • (260.2160) Physical optics : Energy transfer
  • (160.4236) Materials : Nanomaterials

Plasmonic bandpass filters with cascaded rectangular ring resonators

  • Chyong-HUa Chen
  • received 02/26/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 207147
  • [full text: PDF (799) KB)]
  • Abstract: We theoretically present the analysis and the design of the nanoplasmonic bandpass filter with a flat-top spectral characteristics by cascading a series of directly-connected rectangular ring resonators based on metal-insulator-metal waveguides. Analyzed by the equivalent lumped circuit model of the transmission line to plasmonic waveguides, the transmission properties of a symmetric rectangular ring resonator with the direct-connected input and output waveguides is approximately the same as that of a Fabry-Perot resonator. Then, the thin-film design methodology is applied to realize a plasmonic bandpass filter with the squared passband, and an example of cascaded two-rectangular ring resonator structure is numerically demonstrated by using both the transmission line model and two-dimensional finite difference time domain method.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (230.7370) Optical devices : Waveguides
  • (240.6680) Optics at surfaces : Surface plasmons
  • (310.4165) Thin films : Multilayer design
  • (130.7408) Integrated optics : Wavelength filtering devices

High Power Red, Orange, and Green Pr3+:LiYF4 Lasers

  • Philip Metz, Fabian Reichert, Francesca Moglia, Sebastian Müller, Daniel-Timo Marzahl, Christian Kraenkel, and Guenter Huber
  • received 02/26/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 207192
  • [full text: PDF (790) KB)]
  • Abstract: Laser experiments with Pr3+:LiYF4 under excitation with a frequency doubled optically pumped semiconductor laser emitting 5 W at 479 nm were performed at seven different laser wavelengths of 523 nm, 546 nm, 604 nm, 607 nm, 640 nm, 698 nm, and 720 nm. At all these wavelengths the output power exceeded 1 W. The best performance at 523 nm with an output power of 2.9 W at a slope efficiency of 72% and an optical-to-optical efficiency of 67% with respect to the incident pump power represents the highest efficiency ever reported for a praseodymium doped laser material.

Keywords (OCIS):

  • (140.3380) Lasers and laser optics : Laser materials
  • (140.3460) Lasers and laser optics : Lasers
  • (140.3580) Lasers and laser optics : Lasers, solid-state

Influence of pollutants in the magneto-dielectric response of silicon nanoparticles

  • Juan Sanz, Rodrigo Alcaraz de la Osa, Angela Barreda, Jose Saiz, Francisco Gonzalez, and Fernando Moreno
  • received 02/27/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 207263
  • [full text: PDF (6160) KB)]
  • Abstract: The influence of the degree of purity of a silicon nanoparticle on its resonances, either electric or magnetic, is assessed by using Mie theory as well as finite-element simulations. In particular, it is shown that the main effect of the increase of absorption due to the pollutants is observed in the magnetic resonances. Concerning Kerker's conditions for the directionality of the scattering, it is found that both are strongly shifted when the material's purity is varied. Resistive losses confirm the quenching of magnetic resonances, showing that the region of influence in the magnetic dipole resonance is much larger than in the electric one, although it has been found that losses are not critical for silicon content over 99.50 %.

Keywords (OCIS):

  • (290.1350) Scattering : Backscattering
  • (290.4020) Scattering : Mie theory
  • (290.5850) Scattering : Scattering, particles
  • (290.2558) Scattering : Forward scattering

PT-symmetric coupler with a coupling defect: soliton interaction with exceptional point

  • Chao Hang, Yuliy Bludov, Guoxiang Huang, and Vladimir Konotop
  • received 03/05/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 207401
  • [full text: PDF (1522) KB)]
  • Abstract: We study interaction of a soliton in a parity-time ($\PT$) symmetric coupler consisting of two arrays, which has local perturbation of the coupling constant. Such a coupling defect does not change the $\PT$-symmetry of the system, but locally can achieve the exceptional point. We have found that the symmetric solitons after interaction with the defect either transform into breathers of blow up. The dynamics of anti-symmetric solitons is more complex, showing domains of successive broadening of the beam and of the beam splitting in two outwards propagating solitons, in addition to the single breather generation and blow up. All the effects are preserved when the coupling strength in the center of the defect deviates from the exceptional point. If however the coupling is strong enough the only observable outcome of the soliton-defect interaction is the generation of the breather.

Keywords (OCIS):

  • (190.5940) Nonlinear optics : Self-action effects
  • (190.6135) Nonlinear optics : Spatial solitons

An ultra-broadband wide-angle unidirectional plasmonic coupler based on joint effects of plasmonic critical angles and subwavelength metallic gratings

  • Fan Lu, Feng Xiao, Kun Li, and Anshi Xu
  • received 01/08/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 204400
  • [full text: PDF (2248) KB)]
  • Abstract: A unidirectional plasmonic couplers with ultra-broadband and wide-angle coupling efficiency is proposed and demonstrated. Employing the plasmonic critical angle (PCA) phenomenon in conjunction with the effect of subwavelength metallic gratings, a wide incident angular full-width-half-maximum (AFWHM >28 degree), coupling efficiency larger than 50 % and extinction ratio better than 15 dB over an ultra-broad wavelength range 725-985 nm (bandwidth>260 nm) are achieved. The operation principle and performance of the structure are clarified and theoretically illustrated.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (250.5403) Optoelectronics : Plasmonics
  • (310.6628) Thin films : Subwavelength structures, nanostructures

Enhanced photovoltaic performance of organic/silicon nanowire hybrid solar cells by solution-evacuated

  • yong zhang, Wei li Wang, Xian Shao Zou, Bin Zhang, Jun Dong, Qiao Li Niu, and Yi An Yin
  • received 03/19/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 208554
  • [full text: PDF (997) KB)]
  • Abstract: A novel method has been developed to fabricate organic-inorganic hybrid heterojunction solar cells based on n-type silicon nanowire and poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) hybrid structures by evacuating the PEDOT:PSS solution with dip-dropping on the top of silicon nanowires before spin-coating (solution-evacuated). The coverage and contact interface between PEDOT:PSS and silicon nanowire arrays can be dramatically enhanced by optimizing solution-evacuated time. The maximum power conversion efficiency (PCE) reaches 9.22 % for a solution-evacuated time of 2 min compared with 5.17 % for the untreated pristine device. The improvement photovoltaic performance is mainly attributed into better organic coverage and contact with n-type silicon nanowire surface.

Keywords (OCIS):

  • (160.5470) Materials : Polymers
  • (230.4000) Optical devices : Microstructure fabrication
  • (350.6050) Other areas of optics : Solar energy

Articles 1 to 20 of 126 Next Page >>





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