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September


Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides

  • Ray DeCorby, Christopher Dennison, Trevor Allen, Aaron Melnyk, Clinton Potts, and Austin Azar
  • received 07/21/2014; accepted 09/04/2014; posted 09/15/2014; Doc. ID 217292
  • [full text: PDF (649) KB)]
  • Abstract: We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~ 10 pm were resolved by employing a simple peak detection algorithm. Si/SiO2-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region, for a taper length ~ 1 mm. Interrogation of a strain-tuned grating was accomplished using a broadband ASE source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
  • (130.7408) Integrated optics : Wavelength filtering devices

1.9 octave supercontinuum generation in a As2S3 step-index fiber driven by Mid-IR OPCPA

  • Darren Hudson, Matthias Baudisch, Benjamin Eggleton, Jens Biegert, and Daniel Werdehausen
  • received 07/24/2014; accepted 09/04/2014; posted 09/04/2014; Doc. ID 216947
  • [full text: PDF (831) KB)]
  • Abstract: Using a 3.1 µm OPCPA we generate a supercontinuum in a step-index chalcogenide fiber that spans from 1.6 – 5.9 µm at the -20 dB points. The rugged step-index geometry allows for long-term operation, while the spectrum bandwidth is limited by the transmission of the As2S3 fiber.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (320.6629) Ultrafast optics : Supercontinuum generation

Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²+-doped optical fiber

  • Hwa Yaw Tam, Ming-Leung Tse, Zhengyong Liu, and A. Ping Zhang
  • received 07/21/2014; accepted 09/04/2014; posted 09/04/2014; Doc. ID 217488
  • [full text: PDF (2060) KB)]
  • Abstract: A novel microfluidic flowmeter integrated with micro-FBG is presented. Two glass capillaries and a short length of high-light-absorption Co²+-doped optical fiber were stacked inside a larger outer capillary tube. The stack was then drawn into a tapered device. Two microchannels with the diameter of ~50 μm were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²+-doped fiber with waist diameter of ~70 µm, and acts as a flow-rate sensor. A pump laser with wavelength of 1480 nm was utilized to locally heat the micro-FBG, rendering the micro-FBG as miniature “hot-wire” flowmeter. The flow rate of the liquid in the microchannels is determined by the induced wavelength shift of the micro-FBG. The experimental results achieve a minimum detectable flow rate of ~16 nL/s, which is very promising in the use as part of biochips.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (220.4000) Optical design and fabrication : Microstructure fabrication
  • (280.2490) Remote sensing and sensors : Flow diagnostics
  • (280.1415) Remote sensing and sensors : Biological sensing and sensors
  • (060.3735) Fiber optics and optical communications : Fiber Bragg gratings

High sensitivity ring-down evanescent-wave sensing in fiber resonators

  • Saverio Avino, Craig Richmond, Antonio Giorgini, Pietro Malara, Rosa Zullo, Paolo De Natale, and Gianluca Gagliardi
  • received 08/12/2014; accepted 09/04/2014; posted 09/04/2014; Doc. ID 220912
  • [full text: PDF (474) KB)]
  • Abstract: We report on optical-fiber cavity ring-down spectroscopy in the liquid phase using a laser emitting at telecommunication wavelengths. A fiber-ring cavity, comprising a short evanescent-wave coupler for radiation-matter interaction, is used as a sensor while its resonance modes are frequency locked to the laser. Exploiting the intrinsic sensitivity and noise immunity of the cavity ring-down spectroscopy technique, we show that liquid absorption can be detected down to a level which is nearly a factor of 20 above the shot noise limit. We provide a thorough comparison between the experimental results and various noise contributions and address different expressions that can be used to calculate the shot noise equivalent absorbance. As a proof of principle, polyamine detection in aqueous solutions is carried out, demonstrating sensitivity to the sample evaporation with a minimum detectable absorbance of 1.8 x 10^-7 Hz^-1/2, which to our knowledge is the best sensitivity limit reported to date for evanescent-wave sensors.

Keywords (OCIS):

  • (140.4780) Lasers and laser optics : Optical resonators
  • (280.4788) Remote sensing and sensors : Optical sensing and sensors

Tunable all-optical plasmonic rectifier in nanoscale metal-insulator-metal waveguides

  • Yi Xu, Xiaomeng Wang, Haidong Deng, and Kangxian Guo
  • received 07/30/2014; accepted 09/03/2014; posted 09/04/2014; Doc. ID 219997
  • [full text: PDF (1924) KB)]
  • Abstract: We investigate a tunable all-optical plasmonic rectifier based on the nonlinear Fano resonance in a metal-insulator-metal plasmonic waveguide and cavities coupling system. We develop a theoretical model based on the temporal coupled-mode theory to study the device physics of the nanoscale rectifier. We further demonstrate via the finite difference time domain numerical experiment that our idea can be realized in a plasmonic system with an ultracompact size ~120*800 nm^2}. The tunable plasmonic rectifier could facilitate the all-optical signal processing in nanoscale.

Keywords (OCIS):

  • (130.2790) Integrated optics : Guided waves
  • (240.6680) Optics at surfaces : Surface plasmons
  • (230.4555) Optical devices : Coupled resonators

Efficient laser generation of Lamb waves

  • Philipp Huke, Ralf Bergmann, Martin Schroeder, Sandra Hellmers, and Michael Kalms
  • received 06/30/2014; accepted 09/03/2014; posted 09/04/2014; Doc. ID 214915
  • [full text: PDF (476) KB)]
  • Abstract: We report about the efficient generation of Lamb waves for nondestructive testing (NDT) of carbon fiber reinforced plastics (CFRP) with spatially formed laser beams. Therefore we describe the successful introduction of a Liquid Crystal on Silicon (LCoS) based spatial light modulator (SLM) to create predetermined spatial laser light distributions for a flexible Lamb wave excitation. We investigate the influence of the formed beam profiles of the generation laser to the resulting Lamb wave. The further objective of the study is the close adaptation of the laser generated guided waves to a specific testing situation and an optimized defect evaluation.

Keywords (OCIS):

  • (160.5470) Materials : Polymers
  • (280.3375) Remote sensing and sensors : Laser induced ultrasonics

Highly sensitive localized surface plasmon resonance fiber device based upon a structured bi-metal array of nano-wires for environmental sensing

  • Thomas Allsop, Ron Neal, Chengbo Mou, Kyriacos Kalli, and David Webb
  • received 08/08/2014; accepted 09/03/2014; posted 09/04/2014; Doc. ID 220682
  • [full text: PDF (912) KB)]
  • Abstract: We demonstrate a bi-metal coating (platinum and gold or silver) localized surface plasmon resonance fibre device that produces an index spectral sensitivity of over 11,900 nm/RIU, yielding an index resolution of 2×10-5 in the aqueous index regime, which is one of the highest sensitivities achieved with optical fiber sensor. The coatings consist of arrays of bi-metal nano-wires (typical dimensions are ~36 nm radius and length of 20 μm) supported by a silicon dioxide thin film on a thin substrate of germanium, which are perpendicular to the core axis of the supporting D-shaped fiber

Keywords (OCIS):

  • (060.2310) Fiber optics and optical communications : Fiber optics
  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (240.6680) Optics at surfaces : Surface plasmons

Ultra Narrow Linewidth, Stable and Tunable Laser Source for Optical Communication Systems and Spectroscopy

  • Thomas Schneider, Stefan Preussler, Hassanain Al-Taiy, Norman Wenzel, and Jens Klinger
  • received 07/17/2014; accepted 09/03/2014; posted 09/10/2014; Doc. ID 217188
  • [full text: PDF (353) KB)]
  • Abstract: A novel ultra narrow linewidth, stable and tunable single line laser source is demonstrated and experimentally performed. The single spectral line laser is achieved by selecting and amplifying one spectral comb line of a femtosecond-fiber laser via polarization pulling assisted stimulated Brillouin scattering. Stabilization and tuning is performed by additional modulation. First proof of concept results show possible linewidths below 1Hz and a SNR of 47 dB with a tunability of more than 100 nm and a relative stability of ±160 mHz over 5 hours. Such a laser source gives high potential for many different applications like spectroscopy and optical communications.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (140.3570) Lasers and laser optics : Lasers, single-mode
  • (140.3600) Lasers and laser optics : Lasers, tunable
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (290.5900) Scattering : Scattering, stimulated Brillouin

All-optical interconnects using Airy beams

  • Noémi Wiersma, Nicolas Marsal, Marc Sciamanna, and Delphine Wolfersberger
  • received 06/19/2014; accepted 09/02/2014; posted 09/09/2014; Doc. ID 214362
  • [full text: PDF (917) KB)]
  • Abstract: We analyze numerically optical waveguide structures in photorefractive media induced by one or two incoherent counter-propagating Airy beams. Under nonlinear focusing conditions, we show that for a single Airy beam or for two counter-propagating beams with various input positions, multiple waveguiding structures can be photo-induced in the medium. Optical Gaussian beams can be therefore guided with a deflecting trajectory and/or even split into several output beams. This results enables new configurations for all-optical interconnections.

Keywords (OCIS):

  • (190.4420) Nonlinear optics : Nonlinear optics, transverse effects in
  • (190.6135) Nonlinear optics : Spatial solitons

Epi-detection of vibrational phase contrast coherent anti-Stokes Raman scattering

  • Erik Garbacik, J Korterik, Cees Otto, Herman Offerhaus, and Jennifer Herek
  • received 06/09/2014; accepted 09/02/2014; posted 09/08/2014; Doc. ID 212085
  • [full text: PDF (1112) KB)]
  • Abstract: We demonstrate a system for the phase-resolved epi-detection of coherent anti-Stokes Raman scattering (CARS) signals in highly scattering and/or thick samples. With this setup we measure the complex vibrational responses of multiple components in a thick, highly-scattering pharmaceutical tablet in real time, and verify that the epi- and forward-detected information are in very good agreement.

Keywords (OCIS):

  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
  • (190.5650) Nonlinear optics : Raman effect
  • (180.4315) Microscopy : Nonlinear microscopy

Entangled transverse optical vortex

  • Siu-Tat Chui and Lin Zhifang
  • received 05/09/2014; accepted 09/02/2014; posted 09/04/2014; Doc. ID 211450
  • [full text: PDF (323) KB)]
  • Abstract: We discuss a new kind of optical vortex with the angular momentum perpendicular to the flow direction and is entangled in that it is a coherent combination of different orbital angular momentum states of the same sign. This entangled state exhibits many unexpected physical properties. The transverse optical vortex can be generated from the reflection of an electromagnetic wave off an array of ferrite rods. Its vorticity can be reversed by switching the direction of the magnetization of the rods, which usually takes only a nano-second.

Keywords (OCIS):

  • (240.6680) Optics at surfaces : Surface plasmons
  • (260.2110) Physical optics : Electromagnetic optics
  • (260.5740) Physical optics : Resonance
  • (350.4010) Other areas of optics : Microwaves
  • (160.3918) Materials : Metamaterials
  • (350.4238) Other areas of optics : Nanophotonics and photonic crystals

Active Control of Gain Saturation in Fiber Optical Parametric Amplifier Using Stimulated Brillouin Scattering

  • Chaoran Huang, Chester C.T. Shu, Xiaojie Guo, Xuelei Fu, and liang wang
  • received 05/20/2014; accepted 09/02/2014; posted 09/04/2014; Doc. ID 212428
  • [full text: PDF (1772) KB)]
  • Abstract: We have demonstrated the use of stimulated Brillouin scattering (SBS) to control the gain saturation characteristics of fiber optical parametric amplification (FOPA). The saturation can be dynamically deferred or expedited without changing the input FOPA pump and signal parameters. It is observed that the input signal power at saturation can be increased or decreased by up to 6 dB. Experiments are performed to further investigate the role of the SBS-induced nonlinear phase on the power transfer efficiency in the FOPA.

Keywords (OCIS):

  • (190.4370) Nonlinear optics : Nonlinear optics, fibers
  • (190.4410) Nonlinear optics : Nonlinear optics, parametric processes
  • (290.5900) Scattering : Scattering, stimulated Brillouin

Reduced-phase dual-illumination interferometer for ‎measuring large stepped objects

  • Behnam Tayebi, Mohammad Reza Jafarfard, Dug Young Kim, farnaz sharif, Yoon-Sung Bae, and seyed hossein hosseini shokouh
  • received 05/28/2014; accepted 09/02/2014; posted 09/04/2014; Doc. ID 212985
  • [full text: PDF (1195) KB)]
  • Abstract: We present a reduced-phase dual-illumination interferometer (RPDII) that measures topography of a sample with large ‎step height variation. We experimentally demonstrate the basic principle and the feasibility of this novel single shot ‎quantitative phase imaging. Two beams of this interferometer illuminate a sample at different incident angles, two ‎phase of the different incident angles and their phase difference are simultaneously recorded using three spatial ‎frequencies. The relative phase difference between two beams of an RPDII can be controlled by adjusting the angle ‎such that the maximum phase difference is smaller than 2π, and thus there is no phase wrapping ambiguity in the ‎reconstructed phase. One 4f optical system with a transmission grating is used to illuminate the sample with two ‎collimated beams incident at different angles. The feasibility of this technique is demonstrated by measuring the ‎thicknesses of two stepped metal layers with heights of 150 and 660 μm. Although the change in stepped height is ‎more than 1000 times the wavelength of the laser used in our interferometer, the thicknesses of these two metal layers ‎are successfully obtained without the use of an unwrapping algorithm. ‎

Keywords (OCIS):

  • (120.5050) Instrumentation, measurement, and metrology : Phase measurement
  • (110.5086) Imaging systems : Phase unwrapping
  • (090.5694) Holography : Real-time holography

Experimental Demonstration of Free-Space based 120 Gb/s Reconfigurable Card-to-Card Optical Interconnects

  • KE WANG, Ampalavanapilla Nirmalathas, Christina Lim, Efstratios Skafidas, and Kamal Alameh
  • received 07/21/2014; accepted 09/02/2014; posted 09/04/2014; Doc. ID 217470
  • [full text: PDF (834) KB)]
  • Abstract: In this paper, we proposed and experimentally demonstrate a free-space based reconfigurable card-to-card optical interconnect architecture with 16-Carrierless-Amplitude-Phase modulation. Experimental results show that up to 120 Gb/s (3×40 Gb/s) flexible interconnection can be achieved for up to 30 cm distance with a worst-case receiver sensitivity of -9.70 dBm.

Keywords (OCIS):

  • (060.4510) Fiber optics and optical communications : Optical communications
  • (200.4650) Optics in computing : Optical interconnects
  • (060.2605) Fiber optics and optical communications : Free-space optical communication
  • (200.2605) Optics in computing : Free-space optical communication

Switchable beam steering with zenithal bistable liquid-crystal blazed gratings

  • Dimitrios Zografopoulos and Emmanouil Kriezis
  • received 07/28/2014; accepted 09/01/2014; posted 09/04/2014; Doc. ID 219956
  • [full text: PDF (839) KB)]
  • Abstract: Switchable beam steerers based on zenithal bistable liquid crystal gratings are designed and theoretically investigated. The nematic orientation profiles and the optical transmittance properties of the gratings are rigorously calculated, respectively, via a tensorial formulation of the Landau-de Gennes theory and the fullwave finite-element-method. By proper design of the grating geometry, beam steering with high diffraction efficiency is demonstrated between the two stable liquid crystal states. The tolerance of the device performance with respect to material parameters is assessed, evidencing spectral operation windows of more than 50 nm in the visible for a beam steering efficiency higher than 90%.

Keywords (OCIS):

  • (050.1950) Diffraction and gratings : Diffraction gratings
  • (160.3710) Materials : Liquid crystals
  • (230.1360) Optical devices : Beam splitters
  • (230.3720) Optical devices : Liquid-crystal devices
  • (050.1755) Diffraction and gratings : Computational electromagnetic methods

Four-wave mixing and octave-spanning supercontinuum generation in a small core hydrogenated amorphous silicon fiber pumped in the mid-infrared

  • Anna Peacock, Li Shen, Noel Healy, Lin Xu, Hiu Cheng, Todd Day, Jonathan Price, and John Badding
  • received 06/23/2014; accepted 09/01/2014; posted 09/04/2014; Doc. ID 214640
  • [full text: PDF (298) KB)]
  • Abstract: An octave-spanning supercontinumm is generated in a hydrogenated amorphous silicon core fiber when pumped in the mid-infrared regime. The broadband wavelength conversion which extends from the edge of the telecommunications band into the mid-infrared (1.64μm-3.37μm) is generated by a cascaded four-wave mixing process, facilitated by the high material nonlinear figure of merit and the anomalous dispersion of the relatively small 1.7μm diameter core fiber. The four-wave mixing sidebands and corresponding supercontinuum can be tuned through the pump parameters, and show good agreement with the predicted phase-matching curves for the fiber.

Keywords (OCIS):

  • (060.2290) Fiber optics and optical communications : Fiber materials
  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (320.6629) Ultrafast optics : Supercontinuum generation

Coded Aperture Pair for Quantitative Phase Imaging

  • Jiamin Wu, Xing Lin, Yebin Liu, Jinli Suo, and Qionghai Dai
  • received 06/30/2014; accepted 09/01/2014; posted 09/02/2014; Doc. ID 214114
  • [full text: PDF (3480) KB)]
  • Abstract: This letter proposes a novel quantitative phase imaging approach by optically encoding light fields into the complementary image pair followed by computational reconstruction. We demonstrate that the axial intensity derivative for phase recovery can be well estimated by a coded aperture image pair without z axial scanning. The experimental results demonstrate that our approach can achieve higher accuracy and robustness compared with conventional TIE-based approaches with partial coherence illumination.

Keywords (OCIS):

  • (100.5070) Image processing : Phase retrieval
  • (110.0180) Imaging systems : Microscopy
  • (170.1630) Medical optics and biotechnology : Coded aperture imaging
  • (110.1758) Imaging systems : Computational imaging

Angle-insensitive metal-dielectric multilayer bandpass filter

  • Kevin Webb, Sangsik Kim, Mengren Man, and Minghao Qi
  • received 06/24/2014; accepted 09/01/2014; posted 09/02/2014; Doc. ID 214685
  • [full text: PDF (534) KB)]
  • Abstract: We present a metal-dielectric stack bandpass filter that is thin and relatively insensitive to the angle of incidence. Parametric evaluations of the reflection phase shift at the metal-dielectric interface provide insight and design information. This non-trivial phase shift allows coupled Fabry-Perot resonances with far-subwavelength dielectric film thickness, which results in insensitivity to the angle of incidence. Filter passbands in ultraviolet (UV) through visible or longer wavelengths can be achieved by engineering the dielectric thickness and selecting a metal with an appropriate plasma frequency, as examples demonstrate.

Keywords (OCIS):

  • (040.7190) Detectors : Ultraviolet
  • (120.2440) Instrumentation, measurement, and metrology : Filters
  • (160.3900) Materials : Metals
  • (260.3910) Physical optics : Metal optics

Spectral broadening and shaping of nanosecond pulses: towards shaping of single photons from quantum emitters

  • Imad Agha, Kartik Srinivasan, Serkan Ates, and Luca Sapienza
  • received 07/15/2014; accepted 09/01/2014; posted 09/02/2014; Doc. ID 216821
  • [full text: PDF (644) KB)]
  • Abstract: We experimentally demonstrate spectral broadening and shaping of exponentially-decaying nanosecond pulses via nonlinear mixing with a phase-modulated pump in a periodically-poled lithium niobate (PPLN) waveguide. A strong, 1550 nm pulse is imprinted with a temporal phase and used to upconvert a weak 980 nm pulse to 600 nm while simultaneously broadening the spectrum to that of a Lorentzian pulse up to 10 times shorter. While the current experimental demonstration is for spectral shaping, we also provide a numerical study showing the feasibility of subsequent spectral phase correction to achieve temporal compression and re-shaping of a 1 ns mono-exponentially decaying pulse to a 250 ps Lorentzian, which would constitute a complete spectro-temporal waveform shaping protocol. This method, which uses quantum frequency conversion in PPLN with > 100 : 1 signal-to-noise ratio, is compatible with single photon states of light.

Keywords (OCIS):

  • (190.4390) Nonlinear optics : Nonlinear optics, integrated optics
  • (270.0270) Quantum optics : Quantum optics
  • (230.7405) Optical devices : Wavelength conversion devices

Hybrid single source online Fourier transform coherent anti-Stokes Raman scattering / optical coherence tomography

  • Tschackad Kamali, Boris Považay, Sunil Kumar, Yaron Silberberg, Boris Hermann, René Werkmeister, Wolfgang Drexler, and Angelika Unterhuber
  • received 07/28/2014; accepted 09/01/2014; posted 09/02/2014; Doc. ID 219957
  • [full text: PDF (710) KB)]
  • Abstract: We demonstrate a multimodal optical coherence tomography (OCT) and online Fourier transform coherent anti-Stokes Raman scattering (FTCARS) platform using a single sub-12 femtosecond (fs) Ti:Sapphire laser enabling simultaneous extraction of structural and chemical (‘morphomolecular’) information of biological samples. Spectral domain OCT prescreens the specimen providing a fast ultrahigh (4 x 12 µm axial and transverse) resolution wide field morphologic overview. Additional complementary intrinsic molecular information is obtained by zooming into regions of interest for fast label-free chemical mapping with online FTCARS spectroscopy. Background free CARS is based on a Michelson interferometer in combination with a highly linear piezo stage which allows for quick point-to-point extraction of CARS spectra in the fingerprint region in less than 125 ms with a resolution better than 4 cm -¹ without the need for averaging. OCT morphology and CARS spectral maps indicating phosphate and carbonate bond vibrations from human bone samples are extracted to demonstrate the performance of this hybrid imaging platform.

Keywords (OCIS):

  • (110.4500) Imaging systems : Optical coherence tomography
  • (300.6230) Spectroscopy : Spectroscopy, coherent anti-Stokes Raman scattering
  • (180.4315) Microscopy : Nonlinear microscopy

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