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Articles 1 to 20 of 138 Next Page >>


40-GHz photonic waveform generator by linear shaping of four spectral sidebands

  • Christophe Finot
  • received 01/05/2015; accepted 02/27/2015; posted 02/27/2015; Doc. ID 231924
  • [full text: PDF (899) KB)]
  • Abstract: We show that amplitude and phase shaping of only four sidebands of the optical spectrum is sufficient to synthesize parabolic, triangular or flat-top pulse trains at a repetition rate of 40 GHz. Selection of the waveform is easily achieved by changing the phase difference between the inner and outer spectral lines. Experimental results confirm the high quality of the intensity profiles that are obtained.

Keywords (OCIS):

  • (230.6120) Optical devices : Spatial light modulators
  • (320.5540) Ultrafast optics : Pulse shaping

Reconfigurable non-blocking 4-port silicon thermo-optic optical router based on Mach-Zehnder optical switches

  • Lin Yang, Yuhao Xia, Fanfan Zhang, Qiaoshan Chen, Ping Zhou, Lei Zhang, and jianfeng ding
  • received 02/03/2015; accepted 02/26/2015; posted 02/26/2015; Doc. ID 233679
  • [full text: PDF (1595) KB)]
  • Abstract: We demonstrate a reconfigurable non-blocking 4-port silicon thermo-optic optical router based on MZ optical switches. For all optical links in its 9 routing states, the optical SNRs are larger than 15 dB in the wavelength range from 1525 nm to 1565 nm. The optical router can manipulate 50 wavelength-division-multiplexing channels with the data rate of 32 Gbps for each channel in the same wavelength range. Its average energy efficiency is about 16.3 fJ/bit and its response time is about 26 μs.

Keywords (OCIS):

  • (200.4650) Optics in computing : Optical interconnects
  • (230.3120) Optical devices : Integrated optics devices
  • (130.4815) Integrated optics : Optical switching devices

Determining vortex densities of random non-diffracting beams

  • Cheng-Shan Guo, Ben-Yi Wang, Xiao-Lu Ge, and Qing-Yang Yue
  • received 12/11/2014; accepted 02/25/2015; posted 02/27/2015; Doc. ID 230566
  • [full text: PDF (700) KB)]
  • Abstract: We analyzed the evolution and the statistical properties of the optical vortices existed in a random non-diffracting beam (RNDB). Through simulating the evolution of the phase singularities (PSs) of the optical vortices in a RNDB when its ring shaped spatial spectrum is set to possess different phase fluctuations, we found that the optical vortices of the RNDBs can be considered to originate from the zero rings of the Bessel beams with the same ring-shaped structure of the spatial spectrum (but with zero phase fluctuations), and so the average vortex density or the PS density will be determined by the average duration of the zero rings of the corresponding Bessel function. According to this model, we successfully derived, for the first time to our knowledge, an analytical formula for quantitatively predicting the vortex density of the RNDBs. This formula could be helpful for understanding and designing the RNDBs with specific vortex density, and significant in the applications of fabricating photonic crystals based on the RNDBs.

Keywords (OCIS):

  • (050.1970) Diffraction and gratings : Diffractive optics
  • (070.3185) Fourier optics and signal processing : Invariant optical fields
  • (050.4865) Diffraction and gratings : Optical vortices

Compact fiber optic curvature sensors based on super-mode interference in a seven core fiber

  • Guillermo Salceda, Amy Van Newkirk, Jose Antonio-Lopez, Alejandro Martínez-Rios, Axel Schulzgen, and Rodrigo Amezcua
  • received 12/19/2014; accepted 02/25/2015; posted 02/27/2015; Doc. ID 231103
  • [full text: PDF (1576) KB)]
  • Abstract: A compact, low loss, and highly sensitive optical fiber curvature sensor is presented. The device consists of a few-millimeter-long piece of seven-core fiber spliced between two single mode fibers. When the optical fiber device is kept straight, a pronounced interference pattern appears in the transmission spectrum. However, when the device is bent, a spectral shift of the interference pattern is produced and the visibility of the interference notches changes. This allows for using either visibility or spectral shift for sensor interrogation. The dynamic range of the device can be tailored through the proper selection of the length of the seven core fiber. The effects of temperature and refractive index of the external medium on the response of the curvature sensor are also discussed. Linear sensitivity of about 3000 nm/mm-1 for bending was observed experimentally

Keywords (OCIS):

  • (060.2280) Fiber optics and optical communications : Fiber design and fabrication
  • (060.2370) Fiber optics and optical communications : Fiber optics sensors

Nanobump microresonator

  • Misha Sumetsky and Leonid Kochkurov
  • received 01/29/2015; accepted 02/25/2015; posted 02/27/2015; Doc. ID 233557
  • [full text: PDF (493) KB)]
  • Abstract: We introduce a whispering gallery mode (WGM) nanobump microresonator (NBMR) and develop its theory. This microresonator is formed by an asymmetric nanoscale-high deformation of the translationally symmetric optical fiber surface, which is employed in fabrication of Surface Nanoscale Axial Photonics (SNAP) structures. It is shown that an NBMR causes strong localization of WGMs near a closed ray (geodesic) at the fiber surface, provided that this ray is stable. Our theory explains and describes the experimentally observed localization of WGMs by NBMRs and is useful for the design and fabrication of SNAP devices.

Keywords (OCIS):

  • (060.2340) Fiber optics and optical communications : Fiber optics components
  • (230.3990) Optical devices : Micro-optical devices
  • (140.3945) Lasers and laser optics : Microcavities

In vivo optical resolution photoacoustic microscopy using glancing angle deposited nanostructured Fabry-Perot etalons

  • Parsin Haji Reza, Roger Zemp, Michael Brett, and Jason Sorge
  • received 11/26/2014; accepted 02/25/2015; posted 02/25/2015; Doc. ID 228590
  • [full text: PDF (552) KB)]
  • Abstract: In this letter, reflection mode optical resolution photoacoustic microscopy (OR-PAM) using glancing angle deposited (GLAD) nanostructured Fabry-Perot interferometers (FPI) for in vivo applications is reported. GLAD is a single-step physical vapor-deposition (PVD) technique used to fabricate porous nanostructured thin films. Using titanium dioxide, a transparent semiconductor with a high refractive index (n = 2.4), the GLAD technique can be employed to fabricate samples with tailored nano-porosity, refractive index periodicities, and high Q-factor reflectance spectra. The OR-PAM in vivo images of CAM-membrane of 5-day chicken embryo model are demonstrated. The phantom study shows lateral resolution and signal to noise ratio better than 7µm and 35dB respectively. The sensitive GLAD FPI allows photoacoustic imaging down to a few nJ pulse energy. To the best of our knowledge, this is the first time that an optical resolution reflection mode photoacoustic imaging technique using optical detection is demonstrated for in vivo applications.

Keywords (OCIS):

  • (170.3880) Medical optics and biotechnology : Medical and biological imaging
  • (170.5120) Medical optics and biotechnology : Photoacoustic imaging
  • (180.0180) Microscopy : Microscopy
  • (180.5810) Microscopy : Scanning microscopy
  • (170.1065) Medical optics and biotechnology : Acousto-optics

463 MHz Fundamental Mode-locked Fiber Laser Based on Few-layer MoS2 Saturable Absorber

  • Kan Wu, Xiaoyan Zhang, Jun Wang, and Jianping Chen
  • received 01/08/2015; accepted 02/25/2015; posted 02/25/2015; Doc. ID 232046
  • [full text: PDF (470) KB)]
  • Abstract: We report on the passive mode locking operation of a fiber laser with a fundamental repetition rate of 463 MHz based on molybdenum disulfide (MoS2) saturable absorber (SA). By embedding MoS2 into polyvinyl alcohol (PVA) thin film, MoS2-PVA SA was prepared with a modulation depth of 2.7% and a saturation intensity of 137 MW/cm2. The mode-locked fiber laser employed MoS2-PVA SA was achieved with center wavelength of 1556.3 nm, 3-dB bandwidth of 6.1 nm, output power of 5.9 mW and an extinction ratio of up to 97 dB in the RF spectrum. The demonstration of mode locking operation with high fundamental repetition rate and high spectral purity indicates that MoS2-PVA SA can be a good candidate for high-precision ultrafast applications.

Keywords (OCIS):

  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (160.4330) Materials : Nonlinear optical materials

High-power femtosecond mid-infrared optical parametric oscillator at 7 µm based on CdSiP2

  • Suddapalli Chaitanya Kumar, Joachim Krauth, A Steinmann, Kevin Zawilski, Peter Schunemann, Harald Giessen, and Majid Ebrahim-Zadeh
  • received 01/22/2015; accepted 02/24/2015; posted 02/25/2015; Doc. ID 233135
  • [full text: PDF (1515) KB)]
  • Abstract: We report a femtosecond optical parametric oscillator (OPO) for the mid-infrared (mid-IR), generating a record average power of 110 mW at 7 µm. The OPO, based CdSiP2 (CSP) as the nonlinear crystal, provides idler wavelength tuning across 6540-7186 nm with spectral bandwidths >400 nm at -10 dB level over the entire range, and a maximum bandwidth of 478 nm at 6.9 µm. To the best of our knowledge, this is the highest average power generated from a femtosecond OPO in the deep mid-IR. The OPO also provides near-IR signal wavelengths tunable across 1204-1212 nm with a usable power of 450 mW in 418 fs pulses at 1207 nm. The simultaneously measured signal and idler power exhibit a passive stability better than 1.6% and 3% rms, respectively. The mid-IR idler spectral stability is better than 0.1% rms with corresponding signal stability of 0.02% rms over 15 mins. Using the mid-IR idler from the CSP OPO, we perform Fourier-transform spectroscopy to detect liquid phase organic solvent, toluene (C7H8), in the molecular fingerprint region.

Keywords (OCIS):

  • (190.4360) Nonlinear optics : Nonlinear optics, devices
  • (190.4400) Nonlinear optics : Nonlinear optics, materials
  • (190.4970) Nonlinear optics : Parametric oscillators and amplifiers
  • (190.7110) Nonlinear optics : Ultrafast nonlinear optics
  • (320.7110) Ultrafast optics : Ultrafast nonlinear optics

Dual mode locking mechanism for an akinetic dispersive ring cavity swept source

  • Radu Stancu and Adrian Podoleanu
  • received 11/26/2014; accepted 02/24/2015; posted 02/26/2015; Doc. ID 228579
  • [full text: PDF (1148) KB)]
  • Abstract: A fast dual mode-locked (DML) akinetic swept optical source (AKSS), in the 1550 nm wavelength band, operated at high sweep rates up to 797 KHz, was developed. The SS comprises a voltage controlled oscillator (VCO) driven wideband semiconductor optical amplifier (SOA) along with dispersion compensation fiber (DCF), in a ring laser configuration. A Faraday rotating mirror (FRM) was employed in the cavity as reflective element in order to achieve better polarization control. By driving the optical gain medium at a high multi MHz frequency, multiple of the resonant frequency, fR, equal to the inverse round trip time, a first mode locking mechanism is imposed. A second locking mechanism consists in sweeping the radio frequency of the locking signal at a rate slightly detuned from fR. A dynamic linewidth of 0.05 nm is assessed by measuring the decay of interference signal strength versus optical path difference in a Mach-Zender interferometer.

Keywords (OCIS):

  • (140.3560) Lasers and laser optics : Lasers, ring
  • (140.4050) Lasers and laser optics : Mode-locked lasers
  • (250.5980) Optoelectronics : Semiconductor optical amplifiers
  • (130.2035) Integrated optics : Dispersion compensation devices

The effect of scattering loss on connections between classical and quantum processes in second-order nonlinear waveguides

  • Lukas Helt and Michael Steel
  • received 12/11/2014; accepted 02/24/2015; posted 02/25/2015; Doc. ID 230516
  • [full text: PDF (870) KB)]
  • Abstract: We show that a useful connection exists between spontaneous parametric downconversion (SPDC) and sum frequency generation in nonlinear optical waveguides with arbitrary scattering loss, while the same does not hold true for SPDC and difference frequency generation. This result deepens the relationship between quantum and classical second-order nonlinear optical processes in waveguides, and identifies the most accurate characterization of their quantum performance in the presence of loss based solely on classical measurements.

Keywords (OCIS):

  • (190.4390) Nonlinear optics : Nonlinear optics, integrated optics
  • (190.4410) Nonlinear optics : Nonlinear optics, parametric processes
  • (270.0270) Quantum optics : Quantum optics

Enhanced third-harmonic generation in Si-compatible Epsilon-Near-Zero ITO nanolayers

  • Luca Dal Negro, Antonio Capretti, yu wang, and Nader Engheta
  • received 01/21/2015; accepted 02/23/2015; posted 02/24/2015; Doc. ID 232986
  • [full text: PDF (893) KB)]
  • Abstract: We experimentally demonstrate enhanced third-harmonic generation from Indium Tin Oxide nanolayers at telecommunication wavelengths, with an efficiency approximately 600 times larger than crystalline Silicon. This increased optical nonlinearity of the fabricated nanolayers is driven by their epsilon-near-zero response, which can be tailored on-demand in the near infrared. The present material platform is obtained without any specialized nanofabrication process and it is fully compatible with the standard Si planar technology. The proposed approach can lead to largely scalable and highly-integrated optical nonlinearities in Silicon-integrated devices for information processing and optical sensing applications.

Keywords (OCIS):

  • (160.4330) Materials : Nonlinear optical materials
  • (310.6860) Thin films : Thin films, optical properties
  • (310.7005) Thin films : Transparent conductive coatings

Optical coherence photoacoustic microscopy for in vivo multimodal retinal imaging

  • Shuliang Jiao, Xiaojing Liu, Tan Liu, Rong Wen, Yiwen Li, Carmen Puliafito, and Hao Zhang
  • received 11/07/2014; accepted 02/23/2015; posted 02/24/2015; Doc. ID 226482
  • [full text: PDF (2108) KB)]
  • Abstract: We developed an optical coherence photoacoustic microscopy (OC-PAM) system, which can accomplish optical coherence tomography (OCT) and photoacoustic microscopy (PAM) simultaneously by using a single pulsed broadband light source. With a center wavelength of 800 nm and a bandwidth of 30 nm the system is suitable for imaging the retina. Generated from the same group of photons the OCT and PAM images are intrinsically registered. To test the capabilities of the system on multimodal ophthalmic imaging we imaged the retina of pigmented rats. The OCT images showed the retinal structures with quality similar to conventional OCT while the PAM images revealed the distribution of absorbers in the retina. Since the absorption of hemoglobin is relatively weak at around 800 nm, the NIR PAM signals are generated mainly from melanin in the posterior segment of the eye, thus provide melanin specific imaging of the retina.

Keywords (OCIS):

  • (110.4500) Imaging systems : Optical coherence tomography
  • (110.5120) Imaging systems : Photoacoustic imaging
  • (170.4460) Medical optics and biotechnology : Ophthalmic optics and devices
  • (170.4500) Medical optics and biotechnology : Optical coherence tomography

Rogue waves in a normal-dispersion fiber laser

  • Zhanwei Liu, Shumin Zhang, and Frank Wise
  • received 12/15/2014; accepted 02/23/2015; posted 02/24/2015; Doc. ID 230590
  • [full text: PDF (2472) KB)]
  • Abstract: Experimental evidence of rogue wave formation in a normal-dispersion ytterbium fiber laser is reported. Spectral filtering is a primary component of pulse-shaping in normal-dispersion lasers, and we find that the choice of filter dramatically influences the distribution of noise-pulse energies produced by these lasers. With an interference filter in the cavity, non-Gaussian distributions with pulses as large as 6 times the significant wave height are observed. These correspond to pulse energies as high as ~ 50 nJ. Implications for understanding of rogue waves in dispersive pulse propagation are discussed.

Keywords (OCIS):

  • (250.5530) Optoelectronics : Pulse propagation and temporal solitons
  • (320.7090) Ultrafast optics : Ultrafast lasers
  • (060.3510) Fiber optics and optical communications : Lasers, fiber

Enhanced intermodal four-wave mixing for visible and near-infrared wavelength generation in a photonic crystal fiber

  • Jinhui Yuan, Sang Xinzhu, Qiang Wu, Guiyao Zhou, Feng Li, Xian Zhou, Chongxiu Yu, Kuiru Wang, Binbin Yan, Ying Han, Hwa Yaw Tam, and Ping Kong Wai
  • received 01/28/2015; accepted 02/22/2015; posted 02/26/2015; Doc. ID 233460
  • [full text: PDF (442) KB)]
  • Abstract: We demonstrate experimentally an enhanced intermodal four-wave mixing (FWM) process through coupling positively chirped femtosecond pulses into the deeply normal dispersion region of the fundamental mode of an in-house fabricated photonic crystal fiber (PCF). In the intermodal phase-matching scheme, the energy of the pump waves at 800 nm in the fundamental mode is efficiently converted into the anti-Stokes waves around 553 nm and the Stokes waves within the wavelength range of 1445 to 1586 nm in the second-order mode. The maximum conversion efficiency of ηas and ηs of anti-Stokes and Stokes waves can be up to 21 and 16%, respectively. The Stokes frequency shift is 5580 cm1. The fiber bending and intermodal walk-off effect of pulses do not have significant influence on the nonlinear optical process.

Keywords (OCIS):

  • (060.4370) Fiber optics and optical communications : Nonlinear optics, fibers
  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

Thermally-induced light scattering effects as responsible of the degradation of cholesteric liquid crystal lasers

  • jesus etxebarria, josu ortega, Cesar Folcia, Ibon Aramburu, and gerardo sanz-enguita
  • received 02/03/2015; accepted 02/21/2015; posted 02/23/2015; Doc. ID 233579
  • [full text: PDF (372) KB)]
  • Abstract: We have studied the degradation process of the laser emission in a cholesteric liquid crystal laser. We have found that there exists a negative correlation between the laser efficiency and the amount of light scattered by the liquid-crystal sample in the illuminated area. The growth of scattering is attributed to the appearance of small imperfections generated in the sample as a result of certain thermal processes that involve the dye molecules. The scattering implies an increase of the coefficient of distributed losses, which is the main responsible of the rise of the laser threshold.

Keywords (OCIS):

  • (140.3490) Lasers and laser optics : Lasers, distributed-feedback
  • (160.3710) Materials : Liquid crystals
  • (230.3720) Optical devices : Liquid-crystal devices
  • (290.5870) Scattering : Scattering, Rayleigh

Non-reciprocal transmission in photonic lattices based on unidirectional coherent perfect absorption

  • Stefano Longhi
  • received 02/09/2015; accepted 02/21/2015; posted 02/23/2015; Doc. ID 234291
  • [full text: PDF (986) KB)]
  • Abstract: A method for realizing asymmetric (one-way) transmission of discretized light in modulated, linear and purely passive optical lattices is suggested, which exploits the idea of unidirectional coherent perfect absorption. The system consists of a linear photonic lattice of coupled resonators or waveguides, side coupled to a chain of lossy elements, in which light can avoid the occupation of the dissipative sites when propagating in one way, but not in the opposite one. Non-reciprocity requires modulation of the resonator/waveguide parameters, realizing a dissipative optical Aharonov-Bohm diode with non-reciprocal behavior.

Keywords (OCIS):

  • (000.1600) General : Classical and quantum physics
  • (230.3120) Optical devices : Integrated optics devices
  • (230.3240) Optical devices : Isolators
  • (230.7370) Optical devices : Waveguides

Effect of Intrinsic Surface Roughness on the Efficiency of Intermodal Phase Matching in Silica Optical Nanofibers

  • Gilberto Brambilla, Muhammad Abdul Kudus, Peter Horak, and Timothy Lee
  • received 01/12/2015; accepted 02/21/2015; posted 02/23/2015; Doc. ID 229153
  • [full text: PDF (676) KB)]
  • Abstract: We investigate the effect of intrinsic surface roughness associated to frozen thermal oscillations from the fiber fabrication process on the efficiency of third harmonic generation via intermodal phase matching in silica nanofibers. Already a periodic wave with roughness of 0.2 nm reduces the efficiency by roughly 50% in a 1 mm optical nanofiber, with the divergence growing quadratically with distance. The surface wave period does not exhibit a large impact on the efficiency, due to averaging effects. However, both the location of the surface waves with respect to the phase matching radius as well as the surface wave amplitude have substantial effect on the efficiency, with the former presenting the possibility of transferring the power back to the pump wavelength. Simulations with a realistic superposition of random surface waves indicate that the conversion efficiency increases only for a few mm of propagation and reaches a maximum of less than 1%.

Keywords (OCIS):

  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4160) Nonlinear optics : Multiharmonic generation
  • (190.4370) Nonlinear optics : Nonlinear optics, fibers

Self-adaptive vibrometry with CMOS-LCOS digital holography

  • Umberto Bortolozzo, Daniel Dolfi, Jean-Pierre Huignard, Stephanie Norcia-Molin, Arnaud Peigné, and Stefania Residori
  • received 01/14/2015; accepted 02/21/2015; posted 02/23/2015; Doc. ID 232434
  • [full text: PDF (650) KB)]
  • Abstract: A self-adaptive interferometer based on CMOS-LCOS digital holography is here reported for applications involving measurements of very small amplitude vibrations. The two-beam coupling gain is optimized through an electronic feedback while the dynamic character of the hologram allows reaching a high sensitivity of the interferometric measurements even in unstable environments and with strongly distorted wave-fronts. The frequency bandwidth of the adaptive interferometer and its spatial resolution are determined, respectively, by the maximum frame rate and the pixel size of the camera and of the spatial light modulator used to build the digital holographic setup.

Keywords (OCIS):

  • (090.2880) Holography : Holographic interferometry
  • (230.3720) Optical devices : Liquid-crystal devices
  • (090.1995) Holography : Digital holography
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Temperature characteristics of silicon core optical fiber Fabry-Perot interferometer

  • Na Chen, Shaolin Zhang, Ziwen Zhao, Fufei Pang, Zhenyi Chen, Yunqi Liu, and Tingyun Wang
  • received 12/03/2014; accepted 02/20/2015; posted 02/23/2015; Doc. ID 228694
  • [full text: PDF (565) KB)]
  • Abstract: Silicon core optical fiber expanded silicon photonics to specialty fiber platform. Although great challenges still exist for the fiber fabrication, the presence of semiconductor material has already given optical fiber new features and enormous possibilities for fiber based devices and sensors. In this paper, all fiber silicon cavity Fabry-Perot interferometer was made by splicing silicon core silica cladding fiber with conventional single mode silica fiber. The cavity shows high temperature sensitivity around 82pm/°C due to the larger thermo-optical coefficient of silicon material compared with that of silica material.

Keywords (OCIS):

  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (160.6000) Materials : Semiconductor materials
  • (280.6780) Remote sensing and sensors : Temperature

Kinetics of optically-pumped Kr metastables

  • Michael Heaven and Jiande Han
  • received 02/03/2015; accepted 02/19/2015; posted 02/20/2015; Doc. ID 233684
  • [full text: PDF (861) KB)]
  • Abstract: Optically-pumped atomic gas lasers that utilize metastable excited states of rare gas atoms (Rg*) have been demonstrated using both pulsed and CW pump sources. These devices resemble diode-pumped alkali vapor lasers, but have the advantage of using a chemically inert lasing medium. Collisional energy transfer is needed to sustain a population inversion, and He is used as the transfer agent. Consequently, values for the Kr*+He state-to-state energy transfer rate constants are needed for the analysis and prediction of laser performance characteristics. In the present study we report He energy transfer rate constants for Kr* in the 5p[5/2]2, 5p[5/2]3, 5p[1/2]1, and 5s[3/2]1 states.

Keywords (OCIS):

  • (140.0140) Lasers and laser optics : Lasers and laser optics
  • (140.1340) Lasers and laser optics : Atomic gas lasers
  • (140.3298) Lasers and laser optics : Laser beam combining

Articles 1 to 20 of 138 Next Page >>

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