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April


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

Continuous-wave, double-pass second-harmonic generation with 60 % efficiency in a single MgO:PPSLT

  • Matthias Stappel, Jochen Walz, and Daniel Kolbe
  • received 02/12/2014; accepted 04/14/2014; posted 04/17/2014; Doc. ID 206301
  • [full text: PDF (330) KB)]
  • Abstract: We present a double-pass scheme for high efficiency, high power, second-harmonic generation in a single MgO:PPSLT. The device is pumped by a single-frequency, continuous-wave fiber amplifier at a wavelength of 1091 nm. For the double-pass scheme a conversion efficiency of 60 % and a harmonic power of 12.8 W at a wavelength of 545.5 nm with high beam quality (M²<1.2) is achieved. Compared to single-pass second-harmonic generation a double-pass enhancement factor of more than 2 is observed at the highest fundamental pump power.

Keywords (OCIS):

  • (140.7300) Lasers and laser optics : Visible lasers
  • (190.4360) Nonlinear optics : Nonlinear optics, devices
  • (140.3515) Lasers and laser optics : Lasers, frequency doubled

Resolution enhancement of confocal microscopy by subtraction method with vector beams

  • Yuichi Kozawa, Susumu Segawa, and Shunichi Sato
  • received 03/12/2014; accepted 04/14/2014; posted 04/18/2014; Doc. ID 208116
  • [full text: PDF (791) KB)]
  • Abstract: We proposed a new subtraction method using vector beams for resolution enhancement in confocal microscopy. The imaging simulation revealed that the negative side-lobe due to the excess subtraction resulted in the degradation of the object image. The subtraction imaging using vector beams demonstrated high spatial resolution with avoiding the negative side-lobe. Further resolution enhancement beyond 100 nm was predicted by using a flat-top beam obtained by the combination of beams with radial and azimuthal polarizations, and a higher-order transverse mode azimuthally polarized beam without significant negative side-lobe.

Keywords (OCIS):

  • (180.1790) Microscopy : Confocal microscopy
  • (260.5430) Physical optics : Polarization
  • (110.3010) Imaging systems : Image reconstruction techniques

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

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

Three-Dimensional Printing of Tissue Phantoms for Biophotonic Imaging

  • T. Joshua Pfefer, James Coburn, Chia-Pin Liang, Nicholas Woolsey, Jessica Ramella-Roman, Yu Chen, and Jianting Wang
  • received 01/29/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 203528
  • [full text: PDF (1331) KB)]
  • Abstract: We have investigated the potential of tissue phantoms fabricated with thermosoftening- and photopolymerization-based three-dimensional (3D) printers for use in quantitative evaluation of biophotonic imaging systems. Phantoms with 200-micron-diameter channels or greater were fabricated, characterized in terms of their optical properties, and imaged with microscopy, micro-CT and optical coherence tomography. These phantoms were then implemented for assessment of penetration depth in contrast-enhanced hyperspectral reflectance imaging with gold nanorods. Results indicate that 3D-printed phantoms may be suitable for biophotonics, although subsurface imaging is critical to mitigate printer-to-printer variability in matrix homogeneity and feature microstructure.

Keywords (OCIS):

  • (120.4800) Instrumentation, measurement, and metrology : Optical standards and testing
  • (170.3880) Medical optics and biotechnology : Medical and biological imaging
  • (170.7050) Medical optics and biotechnology : Turbid media
  • (110.4234) Imaging systems : Multispectral and hyperspectral imaging

Weak-signal conversion from 1550nm to 532nm with 84% efficiency

  • Aiko Samblowski, Christina Vollmer, Christoph Baune, J. Fiurasek, and Roman Schnabel
  • received 02/12/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 205450
  • [full text: PDF (520) KB)]
  • Abstract: We report on the experimental frequency conversion of a dim, coherent continuous-wave light field from 1550 nm to 532 nm with an external photon-number conversion efficiency of 84.4±1.5%. In contrast to previous works our conversion efficiency value incorporates all losses before the photo-electric detection, including those introduced by frequency filters. We used sum-frequency generation, which was realized in a standing-wave cavity built around a periodically poled type I potassium titanyl phosphate (PPKTP) crystal, pumped by an intense field at 810 nm. Our result is in full agreement with a numerical model. For optimized cavity coupler reflectivities it predicts a conversion efficiency of up to 93% using the same PPKTP crystal.

Keywords (OCIS):

  • (120.3940) Instrumentation, measurement, and metrology : Metrology
  • (190.4223) Nonlinear optics : Nonlinear wave mixing
  • (270.5585) Quantum optics : Quantum information and processing

Quasi-continuous wave Raman lasers at 990 nm and 976 nm based on a three-level Nd:YLF laser

  • Dimitri Geskus, Jonas Jakutis Neto, Saara-Maarit Reijn, Helen Pask, and Niklaus Wetter
  • received 01/28/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 205482
  • [full text: PDF (612) KB)]
  • Abstract: An intracavity Raman laser, based upon a quasi-three-level laser transition in Nd:YLF is reported. Quasi-continuous wave Stokes output power has been observed at 990 nm and 976 nm, with up to 0.88 W of peak output power obtained at 990 nm.

Keywords (OCIS):

  • (140.3530) Lasers and laser optics : Lasers, neodymium
  • (140.3550) Lasers and laser optics : Lasers, Raman
  • (190.2620) Nonlinear optics : Harmonic generation and mixing

Real-time 3D particle manipulation visualized using volume holographic gratings

  • Zhi Chen, Wensheng CHEN, Yves Chevallier, Nanguang Chen, George Barbastathis, Yuan Luo, and Hsin-yu Lu
  • received 03/25/2014; accepted 04/13/2014; posted 04/14/2014; Doc. ID 208893
  • [full text: PDF (638) KB)]
  • Abstract: Holographic optical tweezers extend optical trapping into three dimensions. Volume imaging then becomes a concern as trapped objects are easily moved out of focus of the imaging objective lens. Here we demonstrate a three dimensional real-time interactive optical trapping, manipulating and imaging system based on holographic optical tweezers incorporated with volume holographic microscope. Intensity information about the trapped objects at multiple depths can be captured in a single measurement. This method is compatible with most imaging modes such as bright-field and fluorescence.

Keywords (OCIS):

  • (050.7330) Diffraction and gratings : Volume gratings
  • (090.4220) Holography : Multiplex holography
  • (350.4855) Other areas of optics : Optical tweezers or optical manipulation

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

Temporal focusing-based multiphoton excitation microscopy via digital micromirror device

  • Shean-Jen Chen, Jenq-Nan Yih, Yvonne Hu, Yong Da Sie, Chi-Hsiang Lien, and Li-Chung Cheng
  • received 01/16/2014; accepted 04/13/2014; posted 04/16/2014; Doc. ID 204861
  • [full text: PDF (477) KB)]
  • Abstract: This paper presents an enhanced temporal focusing-based multiphoton excitation (MPE) microscope in which the conventional diffraction grating is replaced by a digital micromirror device (DMD). Experimental results from imaging a thin fluorescence film show that the 4.0 μm axial resolution of the microscope is comparable to that of a setup incorporating a 600 lines/mm grating; hence, the optical sectioning ability of the proposed setup is demonstrated. Similar to a grating, the DMD diffracts illuminating light frequencies for temporal focusing, but additionally, it also generates arbitrary patterns. Since the DMD is placed on the image-conjugate plane of the objective lens’ focal plane, the MPE pattern can be projected on the focal plane precisely.

Keywords (OCIS):

  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (170.2520) Medical optics and biotechnology : Fluorescence microscopy
  • (170.3880) Medical optics and biotechnology : Medical and biological imaging
  • (180.4315) Microscopy : Nonlinear microscopy

Humidity responsivity of polymer optical fiber Bragg grating sensors

  • Wei Zhang and David Webb
  • received 02/10/2014; accepted 04/12/2014; posted 04/14/2014; Doc. ID 206246
  • [full text: PDF (475) KB)]
  • Abstract: PMMA based optical fiber Bragg gratings have been used for humidity sensing. The characteristic wavelength of the grating is modulated by the water sorption induced swelling and refractive index change in the fiber. The analysis indicates that the swelling varies nonlinearly with the surrounding relative humidity, leading to a nonlinear change of the grating wavelength with humidity. Anisotropic expansion exists in PMMA optical fiber, reducing the humidity responsivity of the grating sensor. The calculated sensor response shows a good agreement with the measured result.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (060.3735) Fiber optics and optical communications : Fiber Bragg gratings
  • (130.5460) Integrated optics : Polymer waveguides

3D reconstruction of external and internal surfaces of transparent objects from polarization state of highlights

  • Florence Drouet, Christophe Stolz, Olivier Laligant, and Olivier Aubreton
  • received 02/25/2014; accepted 04/12/2014; posted 04/14/2014; Doc. ID 207092
  • [full text: PDF (2274) KB)]
  • Abstract: A vision-based method is proposed to measure the 3D shape of both external and internal surfaces of smooth transparent objects. Looking at the reflections of point sources on a specular surface with a polarimetric camera, we combine the measurements of two techniques: shape from distortion and shape from polarization. It permits to recover both the position and orientation of the specular surface for each detected point. The internal surface of transparent objects exhibiting as well a specular component, the same technique is used on the highlights coming from the back surface, taking into account the refraction by using polarimetric ray-tracing.

Keywords (OCIS):

  • (150.6910) Machine vision : Three-dimensional sensing
  • (110.5405) Imaging systems : Polarimetric imaging

Demonstration of all-optical phase noise suppression scheme using optical nonlinearity and conversion/dispersion delay

  • Mohammad Reza Chitgarha, Salman Khaleghi, Morteza Ziyadi, Amirhossein Mohajerin Ariaei, ahmed almaiman, Wajih Daab, Dvora Rogawski, Moshe Tur, Joseph Touch, Carsten Langrock, Martin Fejer, and Alan Willner
  • received 01/02/2014; accepted 04/11/2014; posted 04/14/2014; Doc. ID 203115
  • [full text: PDF (1168) KB)]
  • Abstract: We propose and demonstrate an all-optical phase noise reduction scheme that uses optical nonlinear mixing and tunable optical delays to suppress the low-speed phase noise induced by laser linewidth. By utilizing the phase conjugate copy of the original signal and two narrow-linewidth optical pumps, the phase noise induced by laser linewidth can be reduced by a factor of ~5 for a laser with 500-MHz phase noise bandwidth. The EVM can be improved from ~ 30% to ~ 14% for the same laser linewidth for 40-Gbit/s QPSK signal.

Keywords (OCIS):

  • (060.1660) Fiber optics and optical communications : Coherent communications
  • (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (060.4510) Fiber optics and optical communications : Optical communications

<< Previous Page Articles 21 to 40 of 126 Next Page >>





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