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April


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

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

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

Sub-MHz ultrahigh resolution optical spectrometry based on Brillouin dynamic gratings

  • Yong Kang Dong, Taofei Jiang, Lei Teng, Hongying Zhang, Liang Chen, Xiaoyi Bao, and Zhiwei Lu
  • received 03/19/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 208572
  • [full text: PDF (460) KB)]
  • Abstract: We propose and demonstrate an ultrahigh resolution optical spectrometry based on Brillouin dynamic gratings (BDGs). Taking advantage of creating a long grating in an optical fiber, an ultra-narrow bandwidth optical filter is realized by operating a BDG in a long single-mode fiber (SMF), and the optical spectrometry is performed by sweeping the center wavelength of the BDG-based filter through swept-tuned laser. The BDG-based optical spectrometry features ultrahigh resolution, simple direction detection and a large wavelength coverage. In the experiment, a 4-fm (0.5 MHz) spectral resolution is achieved by operating a BDG in a 400-m SMF, and the wavelength coverage can be readily extended to C+L bands with a commercial tunable laser.

Keywords (OCIS):

  • (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (290.5900) Scattering : Scattering, stimulated Brillouin

Coherent supercontinuum generation using Er-doped fiber laser of hybrid mode-locking

  • Seung-Woo Kim, Seungman Kim, Jiyong Park, Seongheum Han, and Young-Jin Kim
  • received 03/25/2014; accepted 04/15/2014; posted 04/16/2014; Doc. ID 208888
  • [full text: PDF (531) KB)]
  • Abstract: Supercontinuum generation is performed using femtosecond laser pulses produced by combining two distinct mode-locking mechanisms of nonlinear polarization evolution (NPE) with saturable absorption (SA) on an Er-doped fiber oscillator. The generated supercontinuum yields a high level of spectral visibility of 93 %, without the presence of spontaneous emission of post-amplification, being well suited for precision spectroscopy, broad-band interferometry and coherent telecommunications.

Keywords (OCIS):

  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (320.2250) Ultrafast optics : Femtosecond phenomena
  • (320.7090) Ultrafast optics : Ultrafast lasers
  • (320.6629) Ultrafast optics : Supercontinuum generation

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

Robust and broadband frequency conversion in composite crystals with tailored segment widths and $\chi ^{(2)}$ nonlinearities of alternating signs

  • Andon Rangelov, Germano Montemezzani, and Nikolay Vitanov
  • received 03/03/2014; accepted 04/14/2014; posted 04/14/2014; Doc. ID 207588
  • [full text: PDF (678) KB)]
  • Abstract: We propose an efficient, robust and broadband nonlinear optical frequency conversion technique, which uses segmented crystals constructed in analogy with the composite pulses in nuclear magnetic resonance and quantum optics. The composite crystals are made of several macroscopic segments of nonlinear susceptibilities of opposite signs and specific thicknesses, which are determined from the condition to maximize the conversion efficiency with respect to variations in the experimental parameters. These crystals deliver broadband operation for significantly lower pump intensities than single bulk crystals. We demonstrate this technique by numerical simulation of sum frequency generation in MgO:LiNbO$_{3}$ crystal.

Keywords (OCIS):

  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

High power and highly efficient amplification of radially polarized beam using Yb doped double-clad fiber

  • Yuichi Kozawa, Shunichi Sato, and Shinya Kanazawa
  • received 03/06/2014; accepted 04/14/2014; posted 04/14/2014; Doc. ID 207796
  • [full text: PDF (701) KB)]
  • Abstract: We demonstrated the amplification of a radially polarized beam by using an Yb doped double clad fiber. The output power of the amplified beam reached 21 W at the pump power of 30 W. The generation of amplified spontaneous emission was suppressed by applying a seed beam with sufficient power. The intensity and polarization distributions of the seed beam were well maintained after the amplification.

Keywords (OCIS):

  • (060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
  • (140.4480) Lasers and laser optics : Optical amplifiers
  • (260.5430) Physical optics : Polarization

Flexible ultra-flat optical frequency comb generator using a single-driven dual-parallel Mach-Zehnder modulator

  • Qiang Wang, Li Huo, Yanfei Xing, and Bingkun Zhou
  • received 01/30/2014; accepted 04/14/2014; posted 04/14/2014; Doc. ID 205782
  • [full text: PDF (1562) KB)]
  • Abstract: We propose and experimentally demonstrate a simple and cost-effective ultra-flat optical frequency comb (OFC) generator by directly modulating a standalone dual-parallel Mach-Zehnder modulator (DP-MZM) with only one radio frequency (RF) signal without any other assistant devices. 5- and 7-tone OFC with exactly the same intensity can be theoretically generated using two sets of parameters obtained by solving equations derived from the DP-MZM modulation model. In good agreement with the theoretical results, 5- and 7-tone OFC with flatness within 0.1 dB and 1 dB are experimentally demonstrated, respectively.

Keywords (OCIS):

  • (060.4080) Fiber optics and optical communications : Modulation
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics

Optical dipole mirror for cold atoms based on a metallic diffraction grating

  • Tomasz Kawalec, Dobroslawa Bartoszek-Bober, Roman Panas, Jacek Fiutowski, Aleksandra Plawecka, and Horst-Günter Rubahn
  • received 02/14/2014; accepted 04/14/2014; posted 04/14/2014; Doc. ID 206380
  • [full text: PDF (1492) KB)]
  • Abstract: We report on the realization of a plasmonic dipole mirror for cold atoms based on a metallic grating coupler. A cloud of atoms is reflected by the repulsive potential generated by surface plasmon polaritons excited on a reflection gold grating by a 780 nm laser beam. Experimentally and numerically determined mirror efficiencies are close to 100 %. The intensity of SPPs above a real grating coupler and the atomic trajectories as well as the momentum dispersion of the atom cloud being reflected are computed. A suggestion is given on how the plasmonic mirror might serve as an optical atom chip.

Keywords (OCIS):

  • (140.3320) Lasers and laser optics : Laser cooling
  • (230.1950) Optical devices : Diffraction gratings
  • (230.4000) Optical devices : Microstructure fabrication
  • (240.6680) Optics at surfaces : Surface plasmons

Trade-off between Linewidth and Slip Rate in a Mode-Locked Laser Model

  • Richard Moore
  • received 02/27/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 207128
  • [full text: PDF (558) KB)]
  • Abstract: We demonstrate a trade-off between linewidth and loss-of-lock frequency in a mode-locked laser employing active feedback to control the carrier-envelope offset phase difference. In frequency metrology applications, the linewidth translates directly to uncertainty in the measured frequency, while the impact of lock loss and recovery on the measured frequency is less well understood. We reduce the dynamics to stochastic differential equations, specifically diffusion processes, and compare the linearized linewidth to the rate of lock loss determined by the mean time to exit calculated from large deviation theory.

Keywords (OCIS):

  • (140.3430) Lasers and laser optics : Laser theory
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (190.5530) Nonlinear optics : Pulse propagation and temporal solitons

Locking laser frequency of up to 40 GHz offset to a reference with a 10 GHz electro-optic modulator

  • Mingsheng Zhan, Wencui Peng, Lin Zhou, Shitong Long, and Jin Wang
  • received 02/27/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 207200
  • [full text: PDF (708) KB)]
  • Abstract: We demonstrate a method to lock a laser frequency of up to 40 GHz offset to a reference using a 10 GHz waveguide-type electro-optic modulator (EOM). Offsetting is provided by the EOM sidebands, and first- to fourth-order sidebands are generated by changing the power of the EOM's driving radio frequency. By scanning the driving frequency across the 10 GHz bandwidth, the output laser frequency can be tuned over an 80 GHz range (-40 to 40 GHz) by locking a sideband to the reference. This method provides simple, stable, and low-cost generation of phase-coherent laser pairs separated by tens of GHz.

Keywords (OCIS):

  • (140.3600) Lasers and laser optics : Lasers, tunable
  • (230.2090) Optical devices : Electro-optical devices
  • (140.3425) Lasers and laser optics : Laser stabilization
  • (020.3320) Atomic and molecular physics : Laser cooling

Ti:Sapphire-pumped diamond Raman laser with sub-100 fs pulse duration

  • Michelle Murtagh, Jipeng Lin, Richard Mildren, and David Spence
  • received 03/10/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 207224
  • [full text: PDF (367) KB)]
  • Abstract: We report a synchronously pumped femtosecond diamond Raman laser operating at 895 nm with a 33% slope efficiency. Pumped using a mode locked Ti:Sapphire laser at 800 nm with a duration of 170 fs, the bandwidth of the Stokes output is broadened and chirped to enable subsequent pulse shortening to 95 fs using a prism-pair. Modelling results indicate that self phase modulation drives the broadening of the Stokes spectrum in this highly transient laser. Our results demonstrate potential for Raman conversion to extend the wavelength coverage and pulse shorten Ti:Sapphire lasers.

Keywords (OCIS):

  • (140.3550) Lasers and laser optics : Lasers, Raman
  • (140.3560) Lasers and laser optics : Lasers, ring
  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (190.7110) Nonlinear optics : Ultrafast nonlinear optics

Sub-20 ps pulses from a passively Q-switched microchip laser at 1 MHz repetition rate

  • Eva Mehner, Bernd Braun, Benjamin Bernard, Harald Giessen, and Daniel Kopf
  • received 02/19/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 205829
  • [full text: PDF (770) KB)]
  • Abstract: We present a 50 µm Nd3+:YVO4 microchip laser that is passively Q-switched by a semiconductor saturable absorber mirror. To reduce handling problems caused by the small crystal dimensions the 50 µm Nd3+:YVO4 crystal is optically bonded to an undoped YVO4 crystal of a length of about 500 µm. By using a saturable absorber mirror with an effective modulation depth of >10% the system is able to deliver 16 ps pulses at a repetition rate of up to 1.0 MHz. The average laser power is 16 mW at 1,064 nm. To our knowledge these are the shortest Q-switched pulses ever reported from a solid-state laser. The limits in terms of pulse width, repetition rate, output power, and system stability are discussed. Additionally, continuous-wave behaviour is analyzed. Experimental data is compared with the simulation results of the coupled rate equations.

Keywords (OCIS):

  • (140.3530) Lasers and laser optics : Lasers, neodymium
  • (140.3540) Lasers and laser optics : Lasers, Q-switched
  • (140.3580) Lasers and laser optics : Lasers, solid-state
  • (140.3538) Lasers and laser optics : Lasers, pulsed
  • (140.3945) Lasers and laser optics : Microcavities

Articles 1 to 20 of 131 Next Page >>





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