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Sample records for half-period optical pulse

  1. Half-period optical pulse generation using a free-electron laser

    SciTech Connect

    Jaroszynski, D.A.; Chaix, P.; Piovella, N.

    1995-12-31

    Recently there has been growth, in interest in non-equilibrium interaction of half-period long optical pulses with matter. To date the optical pulses have been produced by chopping out a half-period long segment from a longer pulse using a semiconductor switch driven by a femtosecond laser. In this paper we present new methods for producing tunable ultra-short optical pulses as short as half an optical period using a free-electron laser driven by electron bunches with a duration a fraction of an optical period. Two different methods relying on the production of coherent spontaneous emission will be described. In the first method we show that when a train of ultra-short optical pulses as short as one half period. We present calculations which show that the small signal gain is unimportant in the early stages of radiation build up in the cavity when the startup process is dominated by coherent spontaneous emission. To support our proposed method we present encouraging experimental results from the FELIX experiment in the Netherlands which show that interference effects between the coherent spontaneous optical pulses at start-up are very important. The second proposed method relies on the fact that coherent spontaneous emission mimics the undulations of electrons as they pass through the undulator. We show that ultra-short optical pulses are produced by coherent spontaneous emission when ultra-short electron bunches pass through an ultra-short undulator. We discuss the interesting case of such undulator radiation in the presence of an optical cavity and show that the optical pulse can be {open_quotes}taylored{close_quotes} by simply adjusting the optical cavity desynchronism. The proposed methods may be realisable using existing rf driven FELs in the far-infrared.

  2. Optically pulsed electron accelerator

    DOEpatents

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  3. Optically pulsed electron accelerator

    DOEpatents

    Fraser, John S.; Sheffield, Richard L.

    1987-01-01

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  4. Efficient optical pulse stacker system

    DOEpatents

    Seppala, Lynn G.; Haas, Roger A.

    1982-01-01

    Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

  5. Cylindrically polarized nondiffracting optical pulses

    NASA Astrophysics Data System (ADS)

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2016-07-01

    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves are also reported.

  6. Nondegenerate optical parametric chirped pulse amplifier

    DOEpatents

    Jovanovic, Igor; Ebbers, Christopher A.

    2005-03-22

    A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.

  7. Temporal waveguides for optical pulses

    DOE PAGESBeta

    Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

    2016-05-12

    Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created inmore » practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.« less

  8. Pulsed optically pumped frequency standard

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2004-08-01

    We reconsider the idea of a pulsed optically pumped frequency standard conceived in the early 1960s to eliminate the light-shift effect. The development of semiconductor lasers and of pulsed electronic techniques for atomic fountains and new theoretical findings allow an implementation of this idea which may lead to a frequency standard whose frequency stability is limited only by the thermal noise in the short term and by the temperature drift in the long term. We shall also show both theoretically and experimentally the possibility of doubling the atomic quality factor with respect to the classical Ramsey technique approach.

  9. Pulsed Optically Pumped Rb clock

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Levi, F.; Godone, A.; Calosso, C. E.; François, B.; Boudot, R.; Affolderbach, C.; Kang, S.; Gharavipour, M.; Gruet, F.; Mileti, G.

    2016-06-01

    INRIM demonstrated a Rb vapour cell clock based on pulsed optical pumping (POP) with unprecedented frequency stability performances, both in the short and in the medium-long term period. In the frame of a EMRP project, we are developing a new clock based on the same POP principle but adopting solutions aimed at reducing the noise sources affecting the INRIM clock. At the same time, concerning possible technological applications, particular care are devoted in the project to reduce the size and the weight of the clock, still keeping the excellent stability of the INRIM clock. The paper resumes the main results of this activity.

  10. Pulse front adaptive optics in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  11. Apparatus and method for optical pulse measurement

    SciTech Connect

    Trebino, R.P.; Tsang, T.; Fittinghoff, D.N.; Sweetser, J.N.; Krumbuegel, M.A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through (i) use of phase-matched transient grating beam geometry to maximize interaction length, and (ii) use of interface-enhanced third-harmonic generation.

  12. Apparatus and method for optical pulse measurement

    DOEpatents

    Trebino, Rick P.; Tsang, Thomas; Fittinghoff, David N.; Sweetser, John N.; Krumbuegel, Marco A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through i) use of phase-matched transient grating beam geometry to maximize interaction length, and ii) use of interface-enhanced third-harmonic generation.

  13. Wavelet transforms for optical pulse analysis.

    PubMed

    Vázquez, Javier Molina; Mazilu, Michael; Miller, Alan; Galbraith, Ian

    2005-12-01

    An exploration of wavelet transforms for ultrashort optical pulse characterization is given. Some of the most common wavelets are examined to determine the advantages of using the causal quasi-wavelet suggested in Proceedings of the LEOS 15th Annual Meeting (IEEE, 2002), Vol. 2, p. 592, in terms of pulse analysis and, in particular, chirp extraction. Owing to its ability to distinguish between past and future pulse information, the causal quasi-wavelet is found to be highly suitable for optical pulse characterization. PMID:16396051

  14. Is there RFI in pulsed optical SETI?

    NASA Astrophysics Data System (ADS)

    Howard, Andrew B.; Horowitz, Paul

    2001-08-01

    In the 40 year history of SETI, radio frequency interference (RFI) has proven to be the dominant background in microwave searches. As the SETI community broadens its electromagnetic scope and searches for optical beacons, it must characterize and identify backgrounds for pulsed optical SETI. We must ask the question: What is the ``RFI'' for pulsed optical SETI? This paper seeks to answer the question by examining the astrophysical, atmospheric, terrestrial, and instrumental sources of optical pulses of nanosecond timescale. Potential astrophysical/atmospheric sources include airglow and scattered zodiacal light, stellar photon pileup, muon events, and cosmic-ray induced Cerenkov flashes. Terrestrial sources, including lightning and laser communications, appear negligible. Instrumental backgrounds such as scintillation in detector optics and corona breakdown have been the dominant background in our experiments to date, and present significant design challenges for future optical SETI researchers.

  15. Hamiltonian Framework for Short Optical Pulses

    NASA Astrophysics Data System (ADS)

    Amiranashvili, Shalva

    Physics of short optical pulses is an important and active research area in nonlinear optics. In this Chapter we theoretically consider the most extreme representatives of short pulses that contain only several oscillations of electromagnetic field. Description of such pulses is traditionally based on envelope equations and slowly varying envelope approximation, despite the fact that the envelope is not "slow" and, moreover, there is no clear definition of such a "fast" envelope. This happens due to another paradoxical feature: the standard (envelope) generalized nonlinear Schrödinger equation yields very good correspondence to numerical solutions of full Maxwell equations even for few-cycle pulses, the thing that should not be.In what follows we address ultrashort optical pulses using Hamiltonian framework for nonlinear waves. As it appears, the standard optical envelope equation is just a reformulation of general Hamiltonian equations. In a sense, no approximations are required, this is why the generalized nonlinear Schrödinger equation is so effective. Moreover, the Hamiltonian framework contributes greatly to our understanding of "fast" envelopes, ultrashort solitons, stability and radiation of optical pulses. Even the inclusion of dissipative terms is possible making the Hamiltonian approach an universal theoretical tool also in extreme nonlinear optics.

  16. Optical pulse generation using fiber lasers and integrated optics

    SciTech Connect

    Wilcox, R.B.; Browning, D.F.; Burkhart, S.C.; VanWonterghem, B.W.

    1995-03-27

    We have demonstrated an optical pulse forming system using fiber and integrated optics, and have designed a multiple-output system for a proposed fusion laser facility. Our approach is an advancement over previous designs for fusion lasers, and an unusual application of fiber lasers and integrated optics.

  17. Frequency skewed optical pulses for range detection

    NASA Astrophysics Data System (ADS)

    Ozharar, Sarper; Gee, Sangyoun; Quinlan, Franklyn; Delfyett, Peter J., Jr.

    2007-04-01

    Frequency skewed optical pulses are generated via both a composite cavity structure in a fiberized semiconductor optical amplifier ring laser and a frequency skew loop outside the laser cavity. The composite cavity technique is similar to rational harmonic mode-locking, however it is based on cavity detuning rather than frequency detuning. These frequency skewed pulses are ideal for range detection applications since their interference results in a range dependent RF signal. The intracavity frequency skewed pulse train showed superior performance in both stability and signal quality.

  18. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOEpatents

    Skupsky, S.; Kessler, T.J.; Letzring, S.A.

    1993-11-16

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse. 10 figures.

  19. System for generating shaped optical pulses and measuring optical pulses using spectral beam deflection (SBD)

    DOEpatents

    Skupsky, Stanley; Kessler, Terrance J.; Letzring, Samuel A.

    1993-01-01

    A temporally shaped or modified optical output pulse is generated from a bandwidth-encoded optical input pulse in a system in which the input pulse is in the form of a beam which is spectrally spread into components contained within the bandwidth, followed by deflection of the spectrally spread beam (SBD) thereby spatially mapping the components in correspondence with the temporal input pulse profile in the focal plane of a lens, and by spatially selective attenuation of selected components in that focal plane. The shaped or modified optical output pulse is then reconstructed from the attenuated spectral components. The pulse-shaping system is particularly useful for generating optical pulses of selected temporal shape over a wide range of pulse duration, such pulses finding application in the fields of optical communication, optical recording and data storage, atomic and molecular spectroscopy and laser fusion. An optical streak camera is also provided which uses SBD to display the beam intensity in the focal plane as a function of time during the input pulse.

  20. Pulse front control with adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  1. Pulse Shepherding in Nonlinear Fiber Optics

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Bergman, L.

    1996-01-01

    In a wavelength division multiplexed fiber system, where pulses on different wavelength beams may co-propagate in a single mode fiber, the cross-phase-modulation (CPM) effects caused by the nonlinearity of the optical fiber are unavoidable. In other words, pulses on different wavelength beams can interact with and affect each other through the intensity dependence of the refractive index of the fiber. Although CPM will not cause energy to be exchanged among the beams, the pulse shapes and locations on these beams can be altered significantly. This phenomenon makes possible the manipulation and control of pulses co-propagating on different wavelength beams through the introduction of a shepherd pulse at a separate wavelength. How this can be accomplished is demonstrated in this paper.

  2. Coherent phonons excited by two optical pulses

    NASA Astrophysics Data System (ADS)

    Semenov, A. L.; Bezbat'ko, D. N.

    2016-02-01

    Theoretical dependences of the amplitude A and phase φ of photoinduced coherent oscillations of the crystal lattice on the delay time μ between two exciting optical pulses have been derived. It has been shown that φ(μ) is a periodic or decreasing function depending on the experimental conditions. Comparison with the experiment on Bi has been carried out.

  3. Optical limiting of short laser pulses

    SciTech Connect

    Liu, J.-C.; Wang, C.-K.; Gel'mukhanov, Faris

    2007-11-15

    The dynamics of pulse propagation accompanied by harmonic generation, stimulated Raman scattering, amplified spontaneous emission, and superfluorescence is studied near the two-photon resonance. We explore the optical limiting of intense and short laser pulses. The numerical solutions of the coupled Bloch and Maxwell's equations for the 4,4{sup '}-bis(dimethylamino) stilbene molecule are compared with the two-photon area theorem. It is shown that the area theorem explains qualitatively the major dynamical properties of pulse propagation even if the propagation is accompanied by the generation of new fields. In agreement with the area theorem, we see that the conventional dependence of the transmittance on the propagation depth is not valid for intense pulses.

  4. Pulsed magnet for magneto-optical experimentation

    NASA Astrophysics Data System (ADS)

    Trabjerg, I.

    1980-10-01

    A high field pulsed magnet system with its associated electronics has been modernized to obtain a device which is easy to use. The magnet has been synchronized to operate with an optical multichannel analyzer; the coil has been miniaturized and tested with success in a pumped conventional dewar with liquid helium and in a tube with flowing gaseous helium. Fields of 20 T have been obtained above 77 K and 14.2 T below that temperature.

  5. Pulsed laser damage to optical fibers

    SciTech Connect

    Allison, S.W.; Gillies, G.T.; Magnuson, D.W.; Pagano, T.S.

    1985-10-01

    This paper describes some observations of pulsed laser damage to optical fibers with emphasis on a damage mode characterized as a linear fracture along the outer core of a fiber. Damage threshold data are presented which illustrate the effects of the focusing lens, end-surface preparation, and type of fiber. An explanation based on fiber-beam misalignment is given and is illustrated by a simple experiment and ray trace.

  6. Optical pulse generator using liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Collins, S. A., Jr.

    1984-01-01

    Numerical optical computing is discussed. A design for an optical pulse generator using a Hughes Liquid crystal light valve and intended for application as an optical clock in a numerical optical computer is considered. The pulse generator is similar in concept to the familiar electronic multivibrator, having a flip-flop and delay units.

  7. Temporal laser pulse manipulation using multiple optical ring-cavities

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

    2010-01-01

    An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

  8. Spectral superresolution with ultrashort optical pulses.

    PubMed

    Berger, Naum K

    2012-01-10

    A superresolution technique for the measurement of transmission, reflection, and absorption spectra is proposed. An ultrashort laser pulse is propagated in a dispersive element and then periodically phase modulated. The temporal modulation is transformed into periodic spectral modulation, for which the number of harmonics, 2M+1, is determined by the modulation index. The modulated pulse is transmitted through (reflected from) the sample to be tested and measured by a spectrometer. By performing 2M+1 measurements for 2M+1 delays between the dispersed pulse and modulation signal, one can restore the spectral response of the sample with superresolution after simple processing. We numerically demonstrate the measurement of the transmission spectrum of an ultranarrow optical filter with a minimum feature of 0.43 pm by an optical spectrum analyzer with a 10 pm resolution. A twentyfold enhancement of the resolution is achieved in the presence of noise with a level of 0.1%. The advantage of the system is its full reconfigurability. PMID:22270515

  9. Optical reprogramming with ultrashort femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans G.; Batista, Ana; König, Karsten

    2015-03-01

    The use of sub-15 femtosecond laser pulses in stem cell research is explored with particular emphasis on the optical reprogramming of somatic cells. The reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be evoked through the ectopic expression of defined transcription factors. Conventional approaches utilize retro/lenti-viruses to deliver genes/transcription factors as well as to facilitate the integration of transcription factors into that of the host genome. However, the use of viruses may result in insertional mutations caused by the random integration of genes and as a result, this may limit the use within clinical applications due to the risk of the formation of cancer. In this study, a new approach is demonstrated in realizing non-viral reprogramming through the use of ultrashort laser pulses, to introduce transcription factors into the cell so as to generate iPS cells.

  10. Optical penetration sensor for pulsed laser welding

    DOEpatents

    Essien, Marcelino; Keicher, David M.; Schlienger, M. Eric; Jellison, James L.

    2000-01-01

    An apparatus and method for determining the penetration of the weld pool created from pulsed laser welding and more particularly to an apparatus and method of utilizing an optical technique to monitor the weld vaporization plume velocity to determine the depth of penetration. A light source directs a beam through a vaporization plume above a weld pool, wherein the plume changes the intensity of the beam, allowing determination of the velocity of the plume. From the velocity of the plume, the depth of the weld is determined.

  11. Suppression of polarization instability in optical pulse correlation remote sensing

    NASA Astrophysics Data System (ADS)

    Lu, Mifang; Kobayashi, Hirokazu; Nonaka, Koji

    2014-05-01

    We have proposed an optical pulse correlation remote sensing technique, which has the advantages of high accuracy and good response linearity. To eliminate the impact of polarization fluctuation on sensing signals, we use a polarization scrambled pulse train (PSP), in which the polarization state of each pulse is randomized. We measure the stability of sensing signal under polarization fluctuation in optical pulse correlation sensing with the PSP light and obtain good stability. Moreover, we demonstrate tensile strain measurement using the optical pulse correlation sensing with the PSP and confirm the linear response to the tensile strain even under polarization changing.

  12. Ultra-short pulse propagation in complex optical systems.

    PubMed

    Fuchs, Ulrike; Zeitner, Uwe; Tünnermann, Andreas

    2005-05-16

    In application of ultra-short laser pulses the pulse parameters have to be controlled accurately. Hence the manipulation of the propagation behavior of ultra-short pulses requires for specially designed optics. We have developed a tool for the simulation of ultra-short laser pulse propagation through complex real optical systems based on a combination of ray-tracing and wave optical propagation methods. For the practical implementation of the approach two commercially available software packages have been linked together, which are ZEMAX and Virtual Optics Lab. The focussing properties of different lenses will be analyzed and the results are demonstrated. PMID:19495292

  13. Enhanced Pulse Compression in Nonlinear Fiber by a WDM Optical Pulse

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Bergman, L.

    1997-01-01

    A new way to compress an optical pulse in a single-mode fiber is presented in this paper. By the use of the cross phase modulation (CPM) effect caused by the nonlinearity of the optical fiber, a shepherd pulse propagating on a different wavelength beam in a wavelength division multiplexed (WDM) single-mode fiber system can be used to enhance the pulse compression of a co-propagating primary pulse.

  14. Steerable THz pulses from thin emitters via optical pulse-front tilt.

    PubMed

    Smith, B C; Whitaker, J F; Rand, S C

    2016-09-01

    A new method of steering THz pulses radiated from a thin emitter excited by tilted optical pulse-fronts has been developed theoretically and validated in a proof-of-concept experiment. This steering technique is potentially efficient and rapid, and it should benefit from a THz-pulse energy that can scale with optical-beam size and magnitude. Conversely, the method employed for measuring the steered THz pulses is also capable of characterizing the pulse-front tilt of an optical beam. PMID:27607678

  15. Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation

    PubMed Central

    Eilenberger, Falk; Kabakova, Irina V.; de Sterke, C. Martijn; Eggleton, Benjamin J.; Pertsch, Thomas

    2013-01-01

    We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations. PMID:24060831

  16. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, Arthur; Trebino, Rick P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques.

  17. Device For Trapping Laser Pulses In An Optical Delay Line

    DOEpatents

    Yu, David U. L.; Bullock, Donald L.

    1997-12-23

    A device for maintaining a high-energy laser pulse within a recirculating optical delay line for a period time to optimize the interaction of the pulse with an electron beam pulse train comprising closely spaced electron micropulses. The delay line allows a single optical pulse to interact with many of the electron micropulses in a single electron beam macropulse in sequence and for the introduction of additional optical pulses to interact with the micropulses of additional electron beam macropulses. The device comprises a polarization-sensitive beam splitter for admitting an optical pulse to and ejecting it from the delay line according to its polarization state, a Pockels cell to control the polarization of the pulse within the delay line for the purpose of maintaining it within the delay line or ejecting it from the delay line, a pair of focusing mirrors positioned so that a collimated incoming optical pulse is focused by one of them to a focal point where the pulse interacts with the electron beam and then afterwards the pulse is recollimated by the second focusing mirror, and a timing device which synchronizes the introduction of the laser pulse into the optical delay line with the arrival of the electron macropulse at the delay line to ensure the interaction of the laser pulse with a prescribed number of electron micropulses in sequence. In a first embodiment of the invention, the principal optical elements are mounted with their axes collinear. In a second embodiment, all principal optical elements are mounted in the configuration of a ring.

  18. Optical pulse frequency conversion inside transformation-optical metamaterials

    NASA Astrophysics Data System (ADS)

    Ginis, Vincent; Tassin, Philippe; Craps, Ben; Danckaert, Jan; Veretennicoff, Irina

    2012-05-01

    Based on the analogy between the Maxwell equations in complex metamaterials and the free-space Maxwell equations on the background of an arbitrary metric, transformation optics allows for the design of metamaterial devices using a geometrical perspective. This intuitive geometrical approach has already generated various novel applications within the elds of invisibility cloaking, electromagnetic beam manipulation, optical information storage, and imaging. Nevertheless, the framework of transformation optics is not limited to three-dimensional transformations and can be extended to four-dimensional metrics, which allow for the implementation of metrics that occur in general relativistic or cosmological models. This enables, for example, the implementation of black hole phenomena and space-time cloaks inside dielectrics with exotic material parameters. In this contribution, we present a time-dependent metamaterial device that mimics the cosmological redshift. Theoretically, the transformation-optical analogy requires an innite medium with a permittivity and a permeability that vary monotonically as a function of time. We demonstrate that the cosmological frequency shift can also be reproduced in more realistic devices, considering the fact that practical devices have a nite extent and bound material parameters. Indeed, our recent numerical results indicate that it is possible to alter the frequency of optical pulses in a medium with solely a modulated permittivity. Furthermore, it is shown that the overall frequency shift does not depend on the actual variation of the permittivity. The performance of a nite frequency converter is, for example, not aected by introducing the saw tooth evolution of the material parameters. Finally, we studied the eect of the introduction of realistic metamaterial losses and, surprisingly, we found a very high robustness with respect to this parameter. These results open up the possibility to fabricate this frequency converting device

  19. Amplification of ultra-short optical pulses in a two-pump fiber optical parametric chirped pulse amplifier.

    PubMed

    Mussot, Arnaud; Kudlinski, Alexandre; d'Augères, Patrick Beaure; Hugonnot, Emmanuel

    2013-05-20

    We demonstrate with realistic numerical simulations that fiber optical parametric chirped pulse amplification is able to amplify ultra-short optical pulses. Such amplifiers driven by two-pump waves can amplify pulse bandwidth twice as large as the one of a single pump configuration. We show that pulses as short as 50 fs can be directly amplified. In addition, we take benefit from the saturation regime to achieve spectral broadening which makes possible to reduce pulse duration down to 15 fs. PMID:23736440

  20. Optical Pulse Compression Based on Stationary Rescaled Pulse Propagation in a Comblike Profiled Fiber

    NASA Astrophysics Data System (ADS)

    Inoue, Takashi; Tobioka, Hideaki; Igarashi, Koji; Namiki, Shu

    2006-07-01

    In this paper, optical pulse compression using a comblike profiled fiber (CPF) is theoretically and experimentally studied, in which highly nonlinear fibers and single-mode fibers are alternately concatenated. Stationary rescaled pulse (SRP), is the main focus, which is a recently discovered nonlinear stationary pulse in CPF. The fundamental characteristics of SRP are investigated, and SRP propagation is applied to the design of the CPF pulse compressor. Using the proposed design method, the specifications of the CPF can easily be controlled, such as the compression ratio per step of the CPF or the pedestal of the output pulse. Two experimental results of pulse compression using the CPF based on the proposed design method are shown: 1) pulse compression with a large compression ratio per step of the CPF and 2) low-pedestal and wideband wavelength-tunable compression. A parametric noise-amplification phenomenon occurring in a compression process for an optical pulse sequence is also numerically analyzed.

  1. Ultrafast optical pulse interactions in active disordered condensed matter

    NASA Astrophysics Data System (ADS)

    Siddique, Masood

    2005-07-01

    The goal of this research is to better understand the basic physics that governs the behavior of short-pulsed light propagating in scattering media where either the host medium or the scattering particles exhibit emission or absorption interact with the incident light in form of absorption or stimulated emission. The temporal and spectral dynamics from the interactions of optically active disordered-media with ultrashort optical pulses is the focus of the research performed in this thesis. The interaction processes studied are optical gain, spectral narrowing, fluorescence and pulse lifetime reduction and transport of ultrashort optical pulses in disordered media containing optically active discrete scattering particles. Linear and nonlinear effects are presented where the propagation of picosecond and femtosecond laser pulses in active disordered media is measured experimentally and compared with the theories of Boltzmann radiative transport and diffusive propagation of radiation in disordered media. Active media can be involved in optical processes in disordered media where either the propagation of optical radiation can result in gain or absorption upon optical excitation. A study of optical scattering in non-discrete media such as the biological heterogeneously-continuous scattering tissues is carried out as well. Lasing in random media is one of the outcomes of these results. The optical gain of optically excited active media is divided into clear subdivisions of Amplified Spontaneous Emission, Stimulated Emission and Laser Emission by characterizing them by their temporal and spectral emission.

  2. Generation of frequency-chirped optical pulses with felix

    SciTech Connect

    Knippels, G.M.H.; Meer, A.F.G. van der; Mols, R.F.X.A.M.

    1995-12-31

    Frequency-chirped optical pulses have been produced in the picosecond regime by varying the energy of the electron beam on a microsecond time scale. These pulses were then compressed close to their bandwidth limit by an external pulse compressor. The amount of chirp can be controlled by varying the sweep rate on the electron beam energy and by cavity desynchronisation. To examine the generated chirp we used the following diagnostics: a pulse compressor, a crossed beam autocorrelator, a multichannel electron spectrometer and multichannel optical spectrometer. The compressor is build entirely using reflective optics to permit broad band operation. The autocorrelator is currently operating from 6 {mu}m to 30 {mu}m with one single crystal. It has been used to measure pulses as short as 500 fs. All diagnostics are evacuated to prevent pulse shape distortion or pulse lengthening caused by absorption in ambient water vapour. Pulse length measurements and optical spectra will be presented for different electron beam sweep rates, showing the presence of a frequency chirp. Results on the compression of the optical pulses to their bandwidth limit are given for different electron sweep rates. More experimental results showing the dependence of the amount of chirp on cavity desynchronisation will be presented.

  3. Buffering and trapping ultrashort optical pulses in concatenated Bragg gratings.

    PubMed

    Fu, Shenhe; Liu, Yikun; Li, Yongyao; Song, Liyan; Li, Juntao; Malomed, Boris A; Zhou, Jianying

    2013-12-01

    Strong retardation of ultrashort optical pulses, including their deceleration and stoppage in the form of Bragg solitons in a cascaded Bragg grating (BG) structure, is proposed. The manipulations of the pulses are carried out, using nonlinear effects, in a chirped BG segment which is linked, via a defect, to a uniform grating. The storage of the ultrashort pulses is shown to be very robust with respect to variations of the input field intensity, suggesting the feasibility of storing ultrafast optical pulses in such a structure. Physical estimates are produced for the BGs written in silicon. PMID:24281506

  4. Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses.

    PubMed

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2015-09-01

    We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X-wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics. PMID:26382668

  5. Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses

    NASA Astrophysics Data System (ADS)

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2015-09-01

    We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X -wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics.

  6. Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification

    SciTech Connect

    Jovanovic, I; Brown, C; Wattellier, B; Nielsen, N; Molander, W; Stuart, B; Pennington, D; Barty, C J

    2004-03-22

    The next generation of high-energy petawatt (HEPW)-class lasers will utilize multilayer dielectric diffraction gratings for pulse compression, due to their high efficiency and high damage threshold for picosecond pulses. The peak power of HEPW lasers will be determined by the aperture and damage threshold of the final dielectric grating in the pulse compressor and final focusing optics. We have developed a short-pulse damage test station for accurate determination of the damage threshold of the optics used on future HEPW lasers. Our damage test station is based on a highly stable, high-beam-quality optical parametric chirped-pulse amplifier (OPCPA) operating at 1053 nm at a repetition rate of 10 Hz. We present the design of our OPCPA system pumped by a commercial Q-switched pump laser and the results of the full system characterization. Initial short-pulse damage experiments in the far field using our system have been performed.

  7. Note: External multipass optical trap for counterpropagating pulsed laser applications

    NASA Astrophysics Data System (ADS)

    Graul, J. S.; Ketsdever, A. D.; Andersen, G. P.; Lilly, T. C.

    2013-07-01

    Pulses from a 12 mJ, frequency doubled, 5 ns FWHM, pulsed Nd:YAG laser were split and injected into opposing sides of a symmetric 2.44 m (96 in.) optical ring trap. Using a Pockels cell, the counterpropagating pulses were "locked" into the trap for ≥50 round trips. This optical trap has potential applications ranging from established cavity processes, e.g., laser-based absorption spectroscopy and x-ray production, to new processes such as non-resonant optical lattice gas heating and time-resolved coherent Rayleigh-Brillouin scattering diagnostic studies.

  8. Note: external multipass optical trap for counterpropagating pulsed laser applications.

    PubMed

    Graul, J S; Ketsdever, A D; Andersen, G P; Lilly, T C

    2013-07-01

    Pulses from a 12 mJ, frequency doubled, 5 ns FWHM, pulsed Nd:YAG laser were split and injected into opposing sides of a symmetric 2.44 m (96 in.) optical ring trap. Using a Pockels cell, the counterpropagating pulses were "locked" into the trap for ≥50 round trips. This optical trap has potential applications ranging from established cavity processes, e.g., laser-based absorption spectroscopy and x-ray production, to new processes such as non-resonant optical lattice gas heating and time-resolved coherent Rayleigh-Brillouin scattering diagnostic studies. PMID:23902119

  9. Pulse front adaptive optics: a new method for control of ultrashort laser pulses.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-07-27

    Ultrafast lasers enable a wide range of physics research and the manipulation of short pulses is a critical part of the ultrafast tool kit. Current methods of laser pulse shaping are usually considered separately in either the spatial or the temporal domain, but laser pulses are complex entities existing in four dimensions, so full freedom of manipulation requires advanced forms of spatiotemporal control. We demonstrate through a combination of adaptable diffractive and reflective optical elements - a liquid crystal spatial light modulator (SLM) and a deformable mirror (DM) - decoupled spatial control over the pulse front (temporal group delay) and phase front of an ultra-short pulse was enabled. Pulse front modulation was confirmed through autocorrelation measurements. This new adaptive optics technique, for the first time enabling in principle arbitrary shaping of the pulse front, promises to offer a further level of control for ultrafast lasers. PMID:26367595

  10. Fast magneto-optic switch based on nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Weng, Zi-Hua; Ruan, Jian-Jian; Lin, Shao-Han; Chen, Zhi-Min

    2011-09-01

    The paper studies an all fiber high-speed magneto-optic switch which includes an optical route, a nanosecond pulse generator, and a magnetic field module in order to reduce the switching time of the optical switch in the all optical network. A compact nanosecond pulse generator can be designed based on the special character of the avalanche transistor. The output current pulse of the nanosecond pulse generator is less than 5 ns, while the pulse amplitude is more than 100 V and the pulse width is about 10 to 20 ns, which is able to drive a high-speed magnetic field. A solenoid is used as the magnetic field module, and a bismuth-substituted rare-earth iron garnet single crystal is chosen as the Faraday rotator. By changing the direction of current in the solenoid quickly, the magnetization of the magneto-optic material is reversed, and the optical beam can be rapidly switched. The experimental results indicate that the switching time of the device is about 100 to 400 ns, which can partially meet the demand of the rapid development of the all optical network.

  11. Synchronization using pulsed edge tracking in optical PPM communication system

    NASA Technical Reports Server (NTRS)

    Gagliardi, R.

    1972-01-01

    A pulse position modulated (PPM) optical communication system using narrow pulses of light for data transmission requires accurate time synchronization between transmitter and receiver. The presence of signal energy in the form of optical pulses suggests the use of a pulse edge tracking method of maintaining the necessary timing. The edge tracking operation in a binary PPM system is examined, taking into account the quantum nature of the optical transmissions. Consideration is given first to pure synchronization using a periodic pulsed intensity, then extended to the case where position modulation is present and auxiliary bit decisioning is needed to aid the tracking operation. Performance analysis is made in terms of timing error and its associated statistics. Timing error variances are shown as a function of system signal to noise ratio.

  12. All-optical control and metrology of electron pulses

    NASA Astrophysics Data System (ADS)

    Kealhofer, C.; Schneider, W.; Ehberger, D.; Ryabov, A.; Krausz, F.; Baum, P.

    2016-04-01

    Short electron pulses are central to time-resolved atomic-scale diffraction and electron microscopy, streak cameras, and free-electron lasers. We demonstrate phase-space control and characterization of 5-picometer electron pulses using few-cycle terahertz radiation, extending concepts of microwave electron pulse compression and streaking to terahertz frequencies. Optical-field control of electron pulses provides synchronism to laser pulses and offers a temporal resolution that is ultimately limited by the rise-time of the optical fields applied. We used few-cycle waveforms carried at 0.3 terahertz to compress electron pulses by a factor of 12 with a timing stability of <4 femtoseconds (root mean square) and measure them by means of field-induced beam deflection (streaking). Scaling the concept toward multiterahertz control fields holds promise for approaching the electronic time scale in time-resolved electron diffraction and microscopy.

  13. Laser Pulse-Stretching Using Multiple Optical Ring-Cavities

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet; Lee, Chi-Ming (Technical Monitor)

    2002-01-01

    We describe a simple and passive nanosecond-long (ns-long) laser 'pulse-stretcher' using multiple optical ring-cavities. We present a model of the pulse-stretching process for an arbitrary number of optical ring-cavities. Using the model, we optimize the design of a pulse-stretcher for use in a spontaneous Raman scattering excitation system that avoids laser-induced plasma spark problems. From the optimized design, we then experimentally demonstrate and verify the model with a 3-cavity pulse-stretcher system that converts a 1000 mJ, 8.4 ns-long input laser pulse into an approximately 75 ns-long (FWHM) output laser pulse with a peak power reduction of 0.10X, and an 83% efficiency.

  14. All-optical control and metrology of electron pulses.

    PubMed

    Kealhofer, C; Schneider, W; Ehberger, D; Ryabov, A; Krausz, F; Baum, P

    2016-04-22

    Short electron pulses are central to time-resolved atomic-scale diffraction and electron microscopy, streak cameras, and free-electron lasers. We demonstrate phase-space control and characterization of 5-picometer electron pulses using few-cycle terahertz radiation, extending concepts of microwave electron pulse compression and streaking to terahertz frequencies. Optical-field control of electron pulses provides synchronism to laser pulses and offers a temporal resolution that is ultimately limited by the rise-time of the optical fields applied. We used few-cycle waveforms carried at 0.3 terahertz to compress electron pulses by a factor of 12 with a timing stability of <4 femtoseconds (root mean square) and measure them by means of field-induced beam deflection (streaking). Scaling the concept toward multiterahertz control fields holds promise for approaching the electronic time scale in time-resolved electron diffraction and microscopy. PMID:27102476

  15. Optical pulse synthesis using brillouin selective sideband amplification

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor)

    2002-01-01

    Techniques for producing optical pulses based on Brillouin selective sideband amplification by using a common modulation control signal to modulate both a signal beam to produce multiple sideband signals and a single pump beam to produce multiple pump beams.

  16. Modeling propagation of coherent optical pulses through molecular vapor

    SciTech Connect

    Shore, B.W.; Eberly, J.H.

    1982-01-01

    Results of modeling the mutual coupling of coherent molecular response and coherent optical pulses during propagation are described. The propagation is treated numerically, with particular emphasis on both continuum and discrete behavior associated with the quasicontinuum model.

  17. Phase control and measurement of ultrashort optical pulses

    SciTech Connect

    Sullivan, A.; White, W.E.; Chu, K.C.; Heritage, J.P.

    1995-02-10

    We have used the Direct Optical Spectral Phase Measurement (DOSPM) technique to characterize the cubic phase tuning ability of our pulse stretcher. We have compared the measured phase to the phase determined from cross-correlation measurements.

  18. Single CdTe Nanowire Optical Correlator for Femtojoule Pulses.

    PubMed

    Xin, Chenguang; Yu, Shaoliang; Bao, Qingyang; Wu, Xiaoqin; Chen, Bigeng; Wang, Yipei; Xu, Yingxin; Yang, Zongyin; Tong, Limin

    2016-08-10

    On the basis of the transverse second harmonic generation (TSHG) in a highly nonlinear subwavelength-diameter CdTe nanowire, we demonstrate a single-nanowire optical correlator for femto-second pulse measurement with pulse energy down to femtojoule (fJ) level. Pulses to be measured were equally split and coupled into two ends of a suspending nanowire via tapered optical fibers. The couterpropagating pulses meet each other around the central area of the nanowire, and emit TSHG signal perpendicular to the axis of the nanowire. By transferring the spatial intensity profile of the transverse second harmonic (TSH) image into the time-domain temporal profile of the input pulses, we operate the nanowire as a miniaturized optical correlator. Benefitted from the high nonlinearity and the very small effective mode area of the waveguiding CdTe nanowire, the input energy of the single-nanowire correlator can go down to fJ-level (e.g., 2 fJ/pulse for 1064 nm 200 fs pulses). The miniature fJ-pulse correlator may find applications from low power on-chip optical communication, biophotonics to ultracompact laser spectroscopy. PMID:27414182

  19. Spatiotemporal optical pulse transformation by a resonant diffraction grating

    SciTech Connect

    Golovastikov, N. V.; Bykov, D. A. Doskolovich, L. L. Soifer, V. A.

    2015-11-15

    The diffraction of a spatiotemporal optical pulse by a resonant diffraction grating is considered. The pulse diffraction is described in terms of the signal (the spatiotemporal incident pulse envelope) passage through a linear system. An analytic approximation in the form of a rational function of two variables corresponding to the angular and spatial frequencies has been obtained for the transfer function of the system. A hyperbolic partial differential equation describing the general form of the incident pulse envelope transformation upon diffraction by a resonant diffraction grating has been derived from the transfer function. A solution of this equation has been obtained for the case of normal incidence of a pulse with a central frequency lying near the guided-mode resonance of a diffraction structure. The presented results of numerical simulations of pulse diffraction by a resonant grating show profound changes in the pulse envelope shape that closely correspond to the proposed theoretical description. The results of the paper can be applied in creating new devices for optical pulse shape transformation, in optical information processing problems, and analog optical computations.

  20. Optical pulse propagation via whispering gallery modes in glass spheres

    SciTech Connect

    Whitten, W.B.; Shaw, R.W.; Barnes, M.D.; Ramsey, J.M.

    1997-12-01

    Early in this century, Rayleigh showed that waves could propagate close to the wall of a spherical cavity with very little loss as long as the wavelength was small compared to the cavity circumference. The treatment was primarily for acoustic waves, modeling the whispering gallery effect, but he pointed out that electromagnetic waves should behave similarly. Study of the optical properties of dielectric spheres has received new interest with improvements in optical instrumentation and the emergency of new applications for high-Q resonators. It has recently been shown that optical pulses propagating in whispering gallery modes can be treated analogously to pulses in a fiber optic waveguide. Since the optical fields extend beyond the surface of the sphere, the sphere`s environment could alter propagation properties such as cavity ringdown time. The authors describe here some time and frequency-domain measurements of picosecond pulses in glass spheres of millimeter dimension and discuss potential analytical applications.

  1. Absorbing Boundary Conditions For Optical Pulses In Dispersive, Nonlinear Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Kwak, Dochan (Technical Monitor)

    1995-01-01

    This paper will present results in computational nonlinear optics. An algorithm will be described that provides absorbing boundary conditions for optical pulses in dispersive, nonlinear materials. A new numerical absorber at the boundaries has been developed that is responsive to the spectral content of the pulse. Also, results will be shown of calculations of 2-D electromagnetic nonlinear waves computed by directly integrating in time the nonlinear vector Maxwell's equations. The results will include simulations of "light bullet" like pulses. Here diffraction and dispersion will be counteracted by nonlinear effects. Comparisons will be shown of calculations that use the standard boundary conditions and the new ones.

  2. Nonlinear Optics of Intense Attosecond Light Pulses

    NASA Astrophysics Data System (ADS)

    Nazarkin, Alexander

    2006-10-01

    The interaction of an intense light pulse of "subatomic" duration with a system of multiple discrete quantum states is analyzed. The nonperturbative character of the response to the pulse field leading to an efficient conversion into high order harmonics is predicted. The spatial-temporal evolution of the field is shown to obey a generalized nonlinear wave equation of the double-sine-Gordon type. In addition to the solitary wave structures, it predicts a nontrivial regime of pulse amplification accompanied by extreme temporal self-contraction of the amplified field.

  3. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  4. Electro-Optical Modulator Bias Control Using Bipolar Pulses

    NASA Technical Reports Server (NTRS)

    Farr, William; Kovalik, Joseph

    2007-01-01

    An improved method has been devised for controlling the DC bias applied to an electro-optical crystal that is part of a Mach-Zehnder modulator that generates low-duty-cycle optical pulses for a pulse-position modulation (PPM) optical data-communication system. In such a system, it is desirable to minimize the transmission of light during the intervals between pulses, and for this purpose, it is necessary to maximize the extinction ratio of the modulator (the ratio between the power transmitted during an "on" period and the power transmitted during an "off" period). The present method is related to prior dither error feedback methods, but unlike in those methods, there is no need for an auxiliary modulation subsystem to generate a dithering signal. Instead, as described below, dither is effected through alternation of the polarity of the modulation signal. The upper part of Figure 1 schematically depicts a Mach-Zehnder modulator. The signal applied to the electro-optical crystal consists of a radio-frequency modulating pulse signal, VRF, superimposed on a DC bias Vbias. Maximum extinction occurs during the off (VRF = 0) period if Vbias is set at a value that makes the two optical paths differ by an odd integer multiple of a half wavelength so that the beams traveling along the two paths interfere destructively at the output beam splitter. Assuming that the modulating pulse signal VRF has a rectangular waveform, maximum transmission occurs during the "on" period if the amplitude of VRF is set to a value, V , that shifts the length of the affected optical path by a half wavelength so that now the two beams interfere constructively at the output beam splitter. The modulating pulse signal is AC-coupled from an amplifier to the electro-optical crystal. Sometimes, two successive pulses occur so close in time that the operating point of the amplifier drifts, one result being that there is not enough time for the signal level to return to ground between pulses. Also, the

  5. Ultrafast optical pulse delivery with fibers for nonlinear microscopy

    PubMed Central

    Kim, Daekeun; Choi, Heejin; Yazdanfar, Siavash; So, Peter T. C.

    2008-01-01

    Nonlinear microscopies including multiphoton excitation fluorescence microscopy and multiple-harmonic generation microscopy have recently gained popularity for cellular and tissue imaging. The optimization of these imaging methods for minimally invasive use will require optical fibers to conduct light into tight space where free space delivery is difficult. The delivery of high peak power laser pulses with optical fibers is limited by dispersion resulting from nonlinear refractive index responses. In this paper, we characterize a variety of commonly used optical fibers in terms of how they affect pulse profile and imaging performance of nonlinear microscopy; the following parameters are quantified: spectral bandwidth and temporal pulse width, two-photon excitation efficiency, and optical resolution. A theoretical explanation for the measured performance of these is also provided. PMID:18816597

  6. Subpicosecond optical pulse compression via an integrated nonlinear chirper.

    PubMed

    Peccianti, Marco; Ferrera, Marcello; Razzari, Luca; Morandotti, Roberto; Little, Brent E; Chu, Sai T; Moss, David J

    2010-04-12

    Photonic integrated circuits (PICs) capable of ultra-fast, signal processing are recognized as being fundamental for future applications involving ultra-short optical pulse propagation, including the ability to meet the exponentially growing global fiber-optic telecommunications bandwidth demand. Integrated all-optical signal processors would carry substantial benefits in terms of performance, cost, footprint, and energy efficiency. Here, we demonstrate an optical pulse compressor based on an integrated nonlinear chirper, capable of operating on a sub-picosecond (> 1Tb/s) time scale. It is CMOS compatible and based on a 45cm long, high index doped silica glass waveguide we achieve pulse compression at relatively low input peak powers, due to the high nonlinearity and low linear and nonlinear losses of the device. The flexibility of this platform in terms of nonlinearity and dispersion allows the implementation of several compression schemes. PMID:20588602

  7. Recovering the propagation delay of an optical pulse.

    PubMed

    Tommasi, Federico; Ignesti, Emilio; Fini, Lorenzo; Cavalieri, Stefano

    2014-11-17

    Causality and special relativity pose an upper limit to the amount of advance that an optical pulse can acquire during a superluminal propagation. Such a limit can be circumvented if the pulse, before entering the superluminal medium, is retarded by letting it propagate under normal dispersion. We present an experimental evidence of this fact by showing that a laser pulse propagating in an atomic vapor, quasi resonant with an inverted transition and in conditions of anomalous dispersion, moves faster if it is previously retarded in a cell containing the same medium with no population inversion. Optical transmission lines often need an amplification stage to overcome the signal attenuation and the unavoidable delay respect to propagation at c; in this paper we tailor such stage to provide also an optical controlled recover of such delay. We believe that our results can open exciting prospects for real-life optical data processing and communication. PMID:25402098

  8. Monolithic hybrid optics for focusing ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Fuchs, U.

    2014-03-01

    Almost any application of ultrashort laser pulses involves focusing them in order to reach high intensities and/or small spot sizes as needed for micro-machining or Femto-LASIK. Hence, it is indispensable to be able to understand pulse front distortion caused by real world optics. Focusing causes pulse front distortion due to aberrations, dispersion and diffraction. Thus, the spatio-temporal profile of ultrashort laser is altered, which increases automatically the pulse duration and the focusing spot. Consequently, the main advantage of having ultrashort laser pulses - pulse durations way below 100 fs - can be lost in that one last step of the experimental set-up by focusing them unfavorable. Since compensating for dispersion, aberration and diffraction effects is quite complicated and not always possible, we pursue a different approach. We present a specially designed monolithic hybrid optics comprising refraction and diffraction effects for tight spatial and temporal focusing of ultrashort laser pulses. Both aims can be put into practice by having a high numerical aperture (NA = 0.35) and low internal dispersion at the same time. The focusing properties are very promising, due to a design, which provides diffraction limited focusing for 100 nm bandwidth at 780 nm center wavelength. Thus, pulses with durations as short as 10 fs can be focused without pulse front distortion. The outstanding performance of this optics is shown in theory and experimentally. Above that, such focusing optics are easily adapted to their special purpose - changing the center wavelength, achromatic bandwidth or even correcting for focusing into material is possible.

  9. High gain broadband amplification of ultraviolet pulses in optical parametric chirped pulse amplifier.

    PubMed

    Wnuk, Paweł; Stepanenko, Yuriy; Radzewicz, Czesław

    2010-04-12

    We report on a high gain amplification of broadband ultraviolet femtosecond pulses in an optical parametric chirped pulse amplifier. Broadband ultraviolet seed pulses were obtained by an achromatic frequency doubling of the output from a femtosecond Ti:Sapphire oscillator. Stretched seed pulses were amplified in a multipass parametric amplifier with a single BBO crystal pumped by a ns frequency quadrupled Nd:YAG laser. A noncollinear configuration was used for a broadband amplification. The total (after compression) amplification of 2.510(5) was achieved, with compressed pulse energy of 30 microJ and pulse duration of 24 fs. We found that the measured gain was limited by thermal effects induced by the absorption of the pump laser by color centers created in the BBO crystal. PMID:20588633

  10. Optical trapping of nanoparticles by ultrashort laser pulses.

    PubMed

    Usman, Anwar; Chiang, Wei-Yi; Masuhara, Hiroshi

    2013-01-01

    Optical trapping with continuous-wave lasers has been a fascinating field in the optical manipulation. It has become a powerful tool for manipulating micrometer-sized objects, and has been widely applied in physics, chemistry, biology, material, and colloidal science. Replacing the continuous-wave- with pulsed-mode laser in optical trapping has already revealed some novel phenomena, including the stable trap, modifiable trapping positions, and controllable directional optical ejections of particles in nanometer scales. Due to two distinctive features; impulsive peak powers and relaxation time between consecutive pulses, the optical trapping with the laser pulses has been demonstrated to have some advantages over conventional continuous-wave lasers, particularly when the particles are within Rayleigh approximation. This would open unprecedented opportunities in both fundamental science and application. This Review summarizes recent advances in the optical trapping with laser pulses and discusses the electromagnetic formulations and physical interpretations of the new phenomena. Its aim is rather to show how beautiful and promising this field will be, and to encourage the in-depth study of this field. PMID:23738434

  11. Laser-Pulse/Fiber-Optic Liquid-Leak Detector

    NASA Technical Reports Server (NTRS)

    Padgett, M. E.

    1986-01-01

    Several potential leak sites monitored using single sensing fiber. Fluid systems monitored quickly for leaks in remote, hazardous, or inaccessible locations by system of compact, lightweight fiber-optic leak sensors presently undergoing development. Sensors installed at potential leak sites as joints, couplings, and fittings. Sensor read by sending laser pulse along fiber, then noting presence or relative amplitude of return pulse. Leak-monitoring technique applicable to wide range of fluid systems and minimizes human exposure to toxic or dangerous fluids.

  12. Optical emission spectroscopy observations of fast pulsed capillary discharge plasmas

    NASA Astrophysics Data System (ADS)

    Avaria, G.; Ruiz, M.; Guzmán, F.; Favre, M.; Wyndham, E. S.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present time resolved optical emission spectroscopic (OES) observations of a low energy, pulsed capillary discharage (PCD). The optical emission from the capillary plasma and plasma jets emitted from the capillary volume was recorded with with a SpectraPro 275 spectrograph, fitted with a MCP gated OMA system, with 15 ns time resolution. The discharge was operated with different gases, including argon, nitrogen, hydrogen and methane, in a repetitive pulsed discharge mode at 10-50 Hz, with, 10-12 kV pulses applied at the cathode side. The time evolution of the electron density was measured using Stark broadening of the Hβ line. Several features of the capillary plasma dynamics, such as ionization growth, wall effects and plasma jet evolution, are inferred from the time evolution of the optical emission.

  13. Nonlinear-optical frequency-doubling metareflector: pulsed regime

    NASA Astrophysics Data System (ADS)

    Popov, A. K.; Myslivets, S. A.

    2016-01-01

    The properties of backward-wave second-harmonic metareflector operating in pulse regime are investigated. It is made of metamaterial which enables phase matching of contra-propagating fundamental and second-harmonic waves. References are given to the works that prove such a possibility. Physical principles underlying differences in the proposed and standard settings as well as between continuous-wave and pulsed regimes are discussed. Pulsed regime is more practicable and has a broader scope of applications. A set of partial differential equations which describe such a reflector with the account for losses are solved numerically. It is shown that unlike second-harmonic generation in standard settings, contra-propagating pulse of second harmonic may become much longer than the incident fundamental one and the difference grows with decrease in the input pulse length as compared to thickness of the metaslab. The revealed properties are important for applications and may manifest themselves beyond the optical wavelength range.

  14. Low-dispersion, high-gain femtosecond optical pulse amplifier.

    PubMed

    Rodenberger, D C; Grossman, C H; Garito, A F

    1990-05-01

    We demonstrate a novel amplifier for femtosecond optical pulses. The output of a colliding-pulse mode-locked laser is amplified to 0.3 microJ per pulse at a repetition rate of 8 kHz by using 1 W of pump power from a copper-vapor laser. Our high-efficiency amplifier focuses the beam for four gain passes through a thin dye stream that uses a Z configuration with matched focusing. Because of low group-velocity dispersion, the output pulses are only slightly broadened, from 63 to 73 fsec, and may be used directly to generate a white-light continuum without pulse compression after amplification. PMID:19767988

  15. Electro-optic measurement of terahertz pulse energy distribution

    NASA Astrophysics Data System (ADS)

    Sun, J. H.; Gallacher, J. G.; Brussaard, G. J. H.; Lemos, N.; Issac, R.; Huang, Z. X.; Dias, J. M.; Jaroszynski, D. A.

    2009-11-01

    An accurate and direct measurement of the energy distribution of a low repetition rate terahertz electromagnetic pulse is challenging because of the lack of sensitive detectors in this spectral range. In this paper, we show how the total energy and energy density distribution of a terahertz electromagnetic pulse can be determined by directly measuring the absolute electric field amplitude and beam energy density distribution using electro-optic detection. This method has potential use as a routine method of measuring the energy density of terahertz pulses that could be applied to evaluating future high power terahertz sources, terahertz imaging, and spatially and temporarily resolved pump-probe experiments.

  16. Femtosecond pulse sequences used for optical manipulation of molecular motion.

    PubMed

    Weiner, A M; Leaird, D E; Wiederrecht, G P; Nelson, K A

    1990-03-16

    Optical control over elementary molecular motion is enhanced with timed sequences of femtosecond (10(-15) second) pulses produced by pulse-shaping techniques. Appropriately timed pulse sequences are used to repetitively drive selected vibrations of a crystal lattice, in a manner analogous to repetitively pushing a child on a swing with appropriate timing to build up a large oscillation amplitude. This process corresponds to repetitively "pushing" molecules along selected paths in the lattice. Amplification of selected vibrational modes and discrimination against other modes are demonstrated. Prospects for more extensive manipulation of molecular and collective behavior and structure are clearly indicated. PMID:17843793

  17. Polarization-controlled optical ring cavity (PORC) tunable pulse stretcher

    NASA Astrophysics Data System (ADS)

    Williamson, Andrew P.; Kiefer, Johannes

    2016-08-01

    A new concept and a theoretical approach for modeling a tunable polarization-controlled optical ring cavity pulse stretcher is demonstrated. The technique discussed herein permits highly simplified and flexible tuning of the temporal shape of nanosecond duration pulses. Using half-wave plates positioned extra- and intracavity, transmission to reflection ratios across both input faces of a polarization beam splitter can easily be controlled. The resulting models indicate a further reduction in peak intensity of 30%, with respect to conventional dielectric beam splitting optical ring cavities, when configured under equivalent and optimized cavity settings.

  18. Methylprednisolone pulse therapy in severe dysthyroid optic neuropathy

    SciTech Connect

    Guy, J.R.; Fagien, S.; Donovan, J.P.; Rubin, M.L. )

    1989-07-01

    Five patients with severe dysthyroid optic neuropathy were treated with intravenous methylprednisolone (1 g daily for 3 consecutive days). Before administration, visual acuity of the more severely affected eyes of each patient was counting fingers at 5 feet, 8/200, 20/400, 20/200, and 20/80. Immediately after completion of pulse therapy, visual acuity improved to 20/25 in four patients and 20/30 in one. Remissions were maintained with oral prednisone and external beam irradiation of the orbit. Pulse methylprednisolone therapy appears to be beneficial in the initial management of severe dysthyroid optic neuropathy.

  19. ULTRASHORT LIGHT PULSES: Formation of subfemtosecond laser pulses in aperiodically poled nonlinear-optical crystals

    NASA Astrophysics Data System (ADS)

    Shutov, I. V.; Novikov, A. A.; Chirkin, A. S.

    2008-03-01

    The method of synthesis of ultrashort laser pulses in nonlinear aperiodically poled crystals based on the simultaneous generation of several higher optical harmonics is considered. The interaction of four waves with multiple frequencies involving three mutually coupled nonlinear three-frequency processes is studied. It is shown that by introducing intense laser radiation into a crystal, pulses of duration of the order of a few hundreds of attoseconds can be produced at the crystal output.

  20. Femtosecond laser pulse induced birefringence in optically isotropic glass.

    SciTech Connect

    Vawter, Gregory Allen; Luk, Ting Shan; Guo, Junpeng; Yang, Pin; Burns, George Robert

    2003-07-01

    We used a regeneratively amplified Ti:sapphire femtosecond laser to create optical birefringence in an isotropic glass medium. Between two crossed polarizers, regions modified by the femtosecond laser show bright transmission with respect to the dark background of the isotropic glass. This observation immediately suggests that these regions possess optical birefringence. The angular dependence of transmission through the laser-modified region is consistent with that of an optically birefringent material. Laser-induced birefringence is demonstrated in different glasses, including fused silica and borosilicate glass. Experimental results indicate that the optical axes of laser-induced birefringence can be controlled by the polarization direction of the femtosecond laser. The amount of laser-induced birefringence depends on the pulse energy level and number of accumulated pulses.

  1. Generation of ultrashort pulses of electrons, X-rays and optical pulses by relativistically strong light

    SciTech Connect

    Umstadter, D.; Banerjee, S.; Chen, S.; Sepke, S.; Maksimchuk, A.; Valenzuela, A.; Rousse, A.; Shah, R.; Phuoc, K. Ta

    2006-04-07

    We report recent results of experiments in which relativistic optical effects play an important role, at peak laser intensities above 1019 W/cm2. These effects are leading to novel radiation sources, all with femtosecond pulse durations: (1) the generation of optical photons by means of pulse compression via relativistic cross-phase modulation, (2) ponderomotive deflection of laser accelerated electron beams, and (3) the generation of well-collimated keV-energy x-ray beams by means of either Thomson scattering or betatron oscillations in ion channels.

  2. Pulse laser assisted optical tweezers for biomedical applications.

    PubMed

    Sugiura, Tadao; Maeda, Saki; Honda, Ayae

    2012-01-01

    Optical tweezers which enables to trap micron to nanometer sized objects by radiation pressure force is utilized for manipulation of particles under a microscope and for measurement of forces between biomolecules. Weak force of optical tweezers causes some limitations such as particle adhesion or steric barrier like lipid membrane in a cell prevent further movement of objects. For biomedical applications we need to overcome these difficulties. We have developed a technique to exert strong instantaneous force by use of a pulse laser beam and to assist conventional optical tweezers. A pulse laser beam has huge instantaneous laser power of more than 1000 times as strong as a conventional continuous-wave laser beam so that the instantaneous force is strong enough to break chemical bonding and molecular force between objects and obstacles. We derive suitable pulse duration for pulse assist of optical tweezers and demonstrate particle manipulation in difficult situations through an experiment of particle removal from sticky surface of glass substrate. PMID:23366922

  3. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  4. Design of Optical Pulse Position Modulation (PPM) Translating Receiver

    SciTech Connect

    Mendez, A J; Hernandez, V J; Gagliardi, R M; Bennett, C V

    2009-06-19

    M-ary pulse position modulation (M-ary PPM) signaling is a means of transmitting multiple bits per symbol in an intensity modulated/direct detection (IM/DD) system. PPM is used in applications with average power limitations. In optical communication systems, PPM becomes challenging to implement at gigabit rates and/or large M, since pulsed signaling requires higher electronic processing bandwidths than the fundamental transmission rate. they have thus been exploring techniques for PPM communications using optical processing. Previous work described a transmitter algorithm that directly translates a bit sequence of N digital bits to the optical pulse position m for any M = 2{sup N}. It has been considerably more difficult to define a similar receiver algorithm that translates the received optical pulse position directly back to a bit sequence with minimal electronic processing. Designs for specific Ms (e.g., 4-ary) have been shown and implemented, but are difficult to scale to larger M. In this work, they present for the first time a generalized PPM translating receiver that is applicable to all M and data rates.

  5. Optically pumped pulsed Li/sub 2/ laser

    SciTech Connect

    Kaslin, V.; Yakushev, O.

    1982-02-01

    Pulsed lasing was obtained for the first time from Li/sub 2/ molecules by optical pumping with radiation from a pulsed copper vapor laser (578.2 nm, pulse repetition frequency 5 kHz). The laser transitions, with wavelengths in the range 867--907 nm, belong to the electronic A/sup 1/..sigma../sup +//sub u/--X/sup 1/..sigma../sup +//sub g/ system. With a pump power of 190 mW, an average output power of 8 mW was achieved with an efficiency for the conversion of the optical pumping energy of 7%. A number of Li/sub 2/ laser emission lines were observed in the superradiant regime.

  6. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    NASA Astrophysics Data System (ADS)

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-02-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems.

  7. Optical ablation by high-power short-pulse lasers

    SciTech Connect

    Stuart, B.C.; Feit, M.D.; Herman, S.; Rubenchik, A.M.; Shore, B.W.; Perry, M.D.

    1996-02-01

    Laser-induced damage threshold measurements were performed on homogeneous and multilayer dielectrics and gold-coated optics at 1053 and 526 nm for pulse durations {tau} ranging from 140 fs to 1 ns. Gold coatings were found, both experimentally and theoretically, to be limited to 0.6 J/cm{sup 2} in the subpicosecond range for 1053-nm pulses. In dielectrics, we find qualitative differences in the morphology of damage and a departure from the diffusion-dominated {tau}{sup 1/2} scaling that indicate that damage results from plasma formation and ablation for {tau}{le}10 ps and from conventional heating and melting for {tau}{approx_gt}50 ps. A theoretical model based on electron production by multiphoton ionization, joule heating, and collisional (avalanche) ionization is in quantitative agreement with both the pulse-width and the wavelength scaling of experimental results. {copyright} {ital 1996 Optical Society of America.}

  8. Recycle Rate in a Pulsed, Optically Pumped Rubidium Laser

    SciTech Connect

    Miller, Wooddy S.; Sulham, Clifford V.; Holtgrave, Jeremy C.; Perram, Glen P.

    2010-10-08

    A pulsed, optically pumped rubidium laser operating in analogy to the diode pumped alkali laser (DPAL) system at pump intensities as high as 750 kW/cm{sup 2} has been demonstrated with output energies of up to 13 {mu}J/pulse. Output energy is dramatically limited by spin-orbit relaxation rates under these high intensity pump conditions. More than 250 photons are available for every rubidium atom in the pumped volume, requiring a high number of cycles per atom during the 2-8 ns duration of the pump pulse. At 550 Torr of ethane, the spin-orbit relaxation rate is too slow to effectively utilize all the incident pump photons. Indeed, a linear dependence of output energy on pump pulse duration for fixed pump energy is demonstrated.

  9. Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

    SciTech Connect

    Cowan, B.; /SLAC

    2006-09-07

    While silicon has several properties making it an attractive material for structure-based laser-driven acceleration, its optical damage threshold, a key parameter for high-gradient acceleration, has been unknown. Here we present measurements of the optical damage threshold of crystalline silicon for ultrafast pulses in the mid-infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm extending longer toward the two-photon absorption threshold at around 2200 nm. We discuss the prevailing theories of ultrafast optical breakdown, describe the experimental setup and preliminary results, and propose a relevant performance parameter for candidate accelerator structures.

  10. Optical pulse compression reflectometry based on single-sideband modulator driven by electrical frequency-modulated pulse

    NASA Astrophysics Data System (ADS)

    Zou, Weiwen; Yu, Lei; Yang, Shuo; Chen, Jianping

    2016-05-01

    We propose a novel scheme to generate a linear frequency-modulated optical pulse with high extinction ratio based on an electrical frequency-modulated pulse and optical single-sideband modulator. This scheme is proved to improve the stability and accuracy of optical pulse compression reflectometry (OPCR). In the experiment, a high spatial resolution of 10 cm and a long measurement range of 10.8 km using a laser source with 2-km coherence length are demonstrated.

  11. Infrared Optical Parametric Chirped Pulse Amplifier for High Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Fuji, T.; Ishii, N.; Metzger, Th.; Teisset, C. Y.; Turi, L.; Baltuška, A.; Forget, N.; Kaplan, D.; Galvanauskas, A.; Krausz, F.

    Rapid advances in high-field physics achieved in recent years, most notably generation of isolated soft X-ray attosecond pulses, owe their success to the development of driver lasers with specific pulse properties. The latter include ultrahigh peak intensity, quasi-monocycle duration, and reliable control over the carrier-envelope phase (CEP) [1],[2]. Although the driver lasers currently employed in this research field operate nearly exclusively in the wavelength region of the Ti:sapphire gain (i.e. around 0.8 µm), a switching over to a longer, infrared (IR) wavelength would offer significant advantages. Because of the λ 2 scaling of the ponderomotive energy, the intensity of IR pulses needed to attain emission at a given X-ray photon energy could be substantially lowered in comparison with the 0.8-µm case [3]-[5]. This is expected to be extraordinarily helpful for up-scaling the X-ray frequency, decreasing the duration of X-ray attosecond pulses by at least a factor of λ 3/2, and suppressing undesired target preionization before the interaction with the strongest half-cycle of the laser pulse. From the standpoint of laser technology, the longer duration of the IR optical period reduces the number of cycles for a given pulse envelope and, therefore, relaxes the demand to the amplifier gain bandwidth, which in the case of 5-fs 0.8-µm pulses typically reaches the extreme > 100 THz.

  12. Test results from LAGEOS-2 optical characterization using pulsed lasers

    NASA Technical Reports Server (NTRS)

    Varghese, Thomas K.; Selden, Michael; Oldham, Thomas; Clarke, Christopher; Zagwodzki, Thomas

    1993-01-01

    The Laser Geodynamic Satellite-2 (LAGEOS-2) has undergone extensive optical testing at NASA Goddard Space Flight Center during 1989. The techniques included measuring the far field diffraction pattern using cw and pulsed lasers. In the pulsed measurement technique, response of the satellite was studied by measuring the far-field diffraction pattern (FFDP) as a function of pulsewidth, wavelength, polarization, position in the FFDP, detector/processing techniques, and satellite orientation. The purpose of the pulsed laser testing was two-fold: (1) to characterize the satellite optical response with the detector and signal processing electronics currently used in most SLR stations using the portable laser ranging standard, and (2) to characterize the satellite response for various conditions using the highest bandwidth optical detector (streak camera) available for the next generation of satellite laser ranging (SLR) technology. The portable ranging standard employed multiple measurement devices and an optical calibration scheme to eliminate range-dependent and amplitude-dependent systematics. These precautions were taken to eliminate/minimize instrumental errors and provide maximum accuracy. For LAGEOS orbit (6000 Km), ground stations are located 34 to 38 Mu radians off the axis of the return signal from the satellite; therefore, an optical mask was used to restrict the field of view (FOV) of detection to this annular region of the FFDP. The two measurement techniques were implemented using an aperture sharing scheme and complemented each other by providing mutual verification.

  13. Quasi-Optical 34-GHz Rf Pulse Compressor

    SciTech Connect

    Hirshfield, Jay L

    2007-06-19

    Designs have been carried out on non-high-vacuum, low-power versions of three- and four-mirror quasi-optical passive and active Ka-band pulse compressors, and prototypes built and tested based on these designs. The active element is a quasi-optical grating employing gas discharge tubes in the gratings. Power gains of about 3:1 were observed experimentally for the passive designs, and about 7:1 with the active designs. High-power, high-vacuum versions of the three-and four-mirror quasi-optical pulse compressors were built and tested at low power. These now await installation and testing using multi-MW power from the 34-GHz magnicon.

  14. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    DOE PAGESBeta

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary D.; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parametermore » dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.« less

  15. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement

    SciTech Connect

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary D.; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-01-01

    A compact optical correlator system that measures both the autocorrelation between two infrared (IR) lights and the cross-correlation between an IR and an ultraviolet (UV) light using a single nonlinear optical crystal has been designed and experimentally demonstrated. The rapid scanning of optical delay line, switching between auto and cross-correlations, crystal angle tuning, and data acquisition and processing are all computer controlled. Pulse widths of an IR light from a mode-locked laser are measured by the correlator and the results are compared with a direct measurement using a high-speed photodetector system. The correlator has been used to study the parameter dependence of the pulse width of a macropulse UV laser designed for laser-assisted hydrogen ion (H-) beam stripping for the Spallation Neutron Source at Oak Ridge National Laboratory.

  16. Fiber Optic Solutions for Short Pulse Lasers

    SciTech Connect

    Beach, R; Dawson, J; Liao, Z; Jovanovic, I; Wattellier, B; Payne, S; Barty, C P

    2003-01-29

    For applications requiring high beam quality radiation from efficient, compact and rugged sources, diffraction limited fiber lasers are ideal, and to date have been demonstrated at average CW power levels exceeding 100 W with near diffraction limited: output. For conventional single-core step-index single-mode fibers, this power level represents the sealing limit because of nonlinear and laser damage considerations. Higher average powers would exceed nonlinear process thresholds such as the Raman and stimulated Brillouin scattering limit, or else damage the fiber due to the high intensity level in the fiber's core. The obvious way to increase the average power capability of fibers is to increase the area of their core. Simply expanding the core dimensions of the fiber allows a straightforward power sealing due to enhanced nonlinear and power handling characteristics that scale directly with the core area. Femtosecond, chirped-pulse, fiber lasers with pulse energies greater than 1mJ have been demonstrated in the literature [2] using this technique. This output energy was still limited by the onset of stimulated Raman scattering. We have pursued an alternative and complimentary approach which is to reduce the intensity of light propagating in the core by distributing it more evenly across the core area via careful design of the refractive index profile [3]. We have also sought to address the primary issue that results from scaling the core. The enhanced power handling capability comes at the expense of beam quality, as increasing the core diameter in standard step index fibers permits multiple transverse modes to lase simultaneously. Although this problem of multimode operation can be mitigated to some extent by appropriately designing the fiber's waveguide structure, limitations such as bend radius loss, sensitivity to thermally induced perturbations of the waveguide structure, and refractive index control, all become more stringent as the core diameter grows

  17. Elucidation of ultrafast photophysics with optical pulse shaping

    NASA Astrophysics Data System (ADS)

    Grumstrup, Erik Martin

    Optical pulse shaping is an incisive tool of laser spectroscopy that allows the experimentalist extensive flexibility to manipulate the electric field of an excitation laser pulse. In this thesis, four applications of optical pulse shaping are examined. In Chapter 2, a partially non-collinear implementation of two-dimensional electronic spectroscopy is demonstrated for the first time on rubidium vapor. The use of a pulse shaper in this context is advantageous as it significantly reduces the complexity of the experimental apparatus. Unfortunately, non-ideal pulse shaping due to pixelation effects in some pulse-shaping devices leads to spurious pulse generation when the spatial masks become highly modulated. To model the effects on recovered 2D spectra, the optical Bloch model is numerically propagated with an explicit inclusion of the electric field modified by pixelation effects. Finally, steps necessary to minimize distortions are outlined. Chapter 3 describes a series of experiments designed to study the mechanism of multiple exciton generation in semiconductor quantum dots through open and closed loop coherent control schemes. The data collected with open loop control methods indicate that the initially formed exciton relaxes on an ultrafast time scale (<20 fs) revealing the reason for a lack of controllability in adaptive, closed-loop optimizations. Chapter 4 of this thesis examines the process of singlet fission in tetracene thin films employing coherent control and ultrafast pulse shaping. Singlet fission is a promising avenue to achieving highly efficient third generation photovoltaic devices, and in this work, closed-loop control suggests that low-frequency nuclear motions play a mechanistic role in tetracene singlet fission. Finally, Chapter 5 examines a specific class of pulse shaping, sinusoidal spectral phase modulation, which is widely employed in the coherent control community as a route toward an intuitive probe into molecular dynamics. This work

  18. Optical gene transfer by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Konig, Karsten; Riemann, Iris; Tirlapur, Uday K.

    2003-07-01

    Targeted transfection of cells is an important technique for gene therapy and related biomedical applications. We delineate how high-intensity (1012 W/cm2) near-infrared (NIR) 80 MHz nanojoule femtosecond laser pulses can create highly localised membrane perforations within a minute focal volume, enabling non-invasive direct transfection of mammalian cells with DNA. We suspended Chinese hamster ovarian (CHO), rat kangaroo kidney epithelial (PtK2) and rat fibroblast cells in 0.5 ml culture medium in a sterile miniaturized cell chamber (JenLab GmbH, Jena, Germany) containing 0.2 μg plasmid DNA vector pEGFP-N1 (4.7 kb), which codes for green fluorescent protein (GFP). The NIR laser beam was introduced into a femtosecond laser scanning microscope (JenLab GmbH, Jena, Germany; focussed on the edge of the cell membrane of a target cell for 16 ms. The integration and expression efficiency of EGFP were assessed in situ by two-photon fluorescence-lifetime imaging using time-correlated single photon counting. The unique capability to transfer foreign DNA safely and efficiently into specific cell types (including stem cells), circumventing mechanical, electrical or chemical means, will have many applications, such as targeted gene therapy and DNA vaccination.

  19. High-Sensitivity Optical Pulse Characterization Using Sagnac Electro-Optic Spectral Shearing Interferometry

    SciTech Connect

    Dorrer, C.; Bromage, J.

    2010-05-04

    An electro-optic spectral shearing interferometer for high-sensitivity optical pulse characterization is described. Two replicas of the test pulse counterpropagate in a Sagnac interferometer with orthogonal polarization states, resulting in two relatively sheared copolarized replicas after temporal phase modulation. The polarization interferometer is intrinsically stable, and its birefringence sets the delay between interfering replicas to reduce the spectrometer resolution requirement. Experimental implementations demonstrate real-time pulse characterization at average powers as low as 1 nWwith spectral shears as high as 280 GHz.

  20. Optical levitation and manipulation of stuck particles with pulsed optical tweezers

    NASA Astrophysics Data System (ADS)

    Ashok Ambardekar, Amol; Li, Yong-Qing

    2005-07-01

    We report on optical levitation and manipulation of microscopic particles that are stuck on a glass surface with pulsed optical tweezers. An infrared pulse laser at 1.06 μm was used to generate a large gradient force (up to 10^-9 N) within a short duration (~45 μs) that overcomes the adhesive interaction between the particles and the glass surface. Then a low-power continuous-wave diode laser at 785 nm was used to capture and manipulate the levitated particle. We have demonstrated that both stuck dielectric and biological micrometer-sized particles, including polystyrene beads, yeast cells, and Bacillus cereus bacteria, can be levitated and manipulated with this technique. We measured the single-pulse levitation efficiency for 2.0 μm polystyrene beads as a function of the pulse energy and of the axial displacement from the stuck particle to the pulsed laser focus, which was as high as 88%.

  1. Optical levitation and manipulation of stuck particles with pulsed optical tweezers.

    PubMed

    Ambardekar, Amol Ashok; Li, Yong-Qing

    2005-07-15

    We report on optical levitation and manipulation of microscopic particles that are stuck on a glass surface with pulsed optical tweezers. An infrared pulse laser at 1.06 microm was used to generate a large gradient force (up to 10(-9) N) within a short duration (approximately 45 micros) that overcomes the adhesive interaction between the particles and the glass surface. Then a low-power continuous-wave diode laser at 785 nm was used to capture and manipulate the levitated particle. We have demonstrated that both stuck dielectric and biological micrometer-sized particles, including polystyrene beads, yeast cells, and Bacillus cereus bacteria, can be levitated and manipulated with this technique. We measured the single-pulse levitation efficiency for 2.0 microm polystyrene beads as a function of the pulse energy and of the axial displacement from the stuck particle to the pulsed laser focus, which was as high as 88%. PMID:16092349

  2. Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

    SciTech Connect

    Cowan, Benjamin M.; /Tech-X, Boulder /SLAC

    2007-11-28

    We present measurements of the optical damage threshold of crystalline silicon in air for ultrafast pulses in the near infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm, extending to 2260 nm. We discuss the motivation for the measurements and give theoretical context. We then describe the experimental setup, diagnostics, and procedure. The results show a breakdown threshold of 0.2J/cm{sup 2} at 1550 nm and 1.06 ps FWHM pulse duration, and a weak dependence on wavelength.

  3. Phase and intensity characterization of femtosecond pulses from a chirped-pulse amplifier by frequency-resolved optical gating

    SciTech Connect

    Kohler, B.; Yakovlev, V.V.; Wilson, K.R.; Squier, J.; DeLong, K.W.; Trebino, R.

    1995-03-01

    Frequency-resolved optical gating (FROG) measurements were made to characterize pulses from a Ti:sapphire chirped-pulse amplified laser system. By characterizing both the pulse intensity and the phase, the FROG data provided the first direct observation to our knowledge of residual phase distortion in a chirped-pulse amplifier. The FROG technique was also used to measure the regenerative amplifier dispersion and to characterize an amplitude-shaped pulse. The data provide an experimental demonstration of the value of FROG for characterizing complex pulses, including tailored femtosecond pulses for quantum control.

  4. Averaging of Replicated Pulses for Enhanced-Dynamic-Range Single-Shot Measurement of Nanosecond Optical Pulses

    SciTech Connect

    Marciante, J.R.; Donaldson, W.R.; Roides, R.G.

    2007-10-04

    Measuring optical pulse shapes beyond the dynamic range of oscilloscopes is achieved by temporal pulse stacking in a low-loss, passive, fiber-optic network. Optical pulses are averaged with their time-delayed replicas without introducing additional noise or jitter, allowing for high-contrast pulse-shape measurements of single-shot events. A dynamic-range enhancement of three bits is experimentally demonstrated and compared with conventional multi-shot averaging. This technique can be extended to yield an increase of up to seven bits of additional dynamic range over nominal oscilloscope performance.

  5. High dynamic extinction ratio and pulse modulation of optical signals

    NASA Astrophysics Data System (ADS)

    Petrov, A.; Tronev, A. V.; Lebedev, V.; Il'ichev, I. V.; Velichko, E.; Shamray, A.

    2015-11-01

    The use of a saturable absorber for increasing the extinction ratio at external modulation of optical signals is considered. An erbium doped fiber was used as the saturable absorber in the experiments. A considerable increase in the static extinction ratio (up to 50 dB) was demonstrated. A rather long erbium doped fiber relaxation time (about 10 ms) was a limiting factor in the case of pulse modulation. Ways of overcoming this drawback are discussed.

  6. Optical feedback signal for ultrashort laser pulse ablation of tissue

    SciTech Connect

    Kim, B.-M.; Feit, M.D.; Rubenchik, A.M.; Mammini, B.M.; Da Silva, L.B.

    1997-07-01

    An optical feedback system for controlled precise tissue ablation is discussed. Our setup includes an ultrashort pulse laser (USPL), and a diagnostic system using analysis of either tissue fluorescence or plasma emission luminescence. Current research is focused on discriminating hard and soft tissues such as bone and spinal cord during surgery using either technique. Our experimental observations exhibit considerable spectroscopic contrast between hard and soft tissue, and both techniques offer promise for a practical diagnostic system.

  7. Optical sinc-shaped Nyquist pulses of exceptional quality

    NASA Astrophysics Data System (ADS)

    Soto, Marcelo A.; Alem, Mehdi; Amin Shoaie, Mohammad; Vedadi, Armand; Brès, Camille-Sophie; Thévenaz, Luc; Schneider, Thomas

    2013-12-01

    Sinc-shaped Nyquist pulses possess a rectangular spectrum, enabling data to be encoded in a minimum spectral bandwidth and satisfying by essence the Nyquist criterion of zero inter-symbol interference (ISI). This property makes them very attractive for communication systems since data transmission rates can be maximized while the bandwidth usage is minimized. However, most of the pulse-shaping methods reported so far have remained rather complex and none has led to ideal sinc pulses. Here a method to produce sinc-shaped Nyquist pulses of very high quality is proposed based on the direct synthesis of a rectangular-shaped and phase-locked frequency comb. The method is highly flexible and can be easily integrated in communication systems, potentially offering a substantial increase in data transmission rates. Further, the high quality and wide tunability of the reported sinc-shaped pulses can also bring benefits to many other fields, such as microwave photonics, light storage and all-optical sampling.

  8. Mismatch characteristics of optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Novák, O.; Turčičová, H.; Divoký, M.; Huynh, J.; Straka, P.

    2014-02-01

    The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump-signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump-signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm-2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry).

  9. Optical frequency up-conversion of UWB monocycle pulse based on pulsed-pump fiber optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Li, Jia; Liang, Yu; Xu, Xing; Cheung, Kim K. Y.; Wong, Kenneth K. Y.

    2009-11-01

    We propose a method to realize frequency up-conversion of UWB monocycle pulse using pulsed-pump fiber optical parametric amplifier (OPA). The spectrum of the amplified signal contains many discrete frequency components which are separated by the modulation frequency of the pump. Each frequency components contain the same spectral information as that of the original signal. By selecting the first-order or higher-order frequency components of the amplified signal and beating in the photodetector, up-converted signal at different frequencies are obtained. We demonstrate frequency up-conversion of baseband UWB monocycle pulse from 3-GHz to 19-GHz in the experiment and frequency up-conversion of pseudo-random binary sequence (PRBS) signal from 3-GHz to 60-GHz in the simulation.

  10. Optical measurement on quantum cascade lasers using femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Cai, Hong

    Quantum cascade lasers (QCLs) as the state-of-the-art mid-infrared (mid-IR) coherent sources have been greatly developed in aspects such as output power, energy efficiency and spectral purity. However, there are additional applications of QCLs in high demand, namely mode-locking, mid-IR modulation, etc. The inherent optical properties and ultrafast carrier dynamics can lead to solutions to these challenges. In this dissertation, we further characterize QCLs using mid-IR femtosecond (fs) pulses generated from a laser system consisting of a Ti:sapphire oscillator, a Ti:sapphire regenerative amplifier, an optical parametric amplifier and a difference frequency generator. We study the Kerr nonlinearity of QCLs by coupling resonant and off-resonant mid-IR fs pulses into an active QCL waveguide. We observe an increase in the spectral width of the transmitted fs pulses as the coupled mid-IR pulse power increases. This is explained by the self-phase modulation effect due to the large Kerr nonlinearity of QCL waveguides. We further confirm this effect by observing the intensity dependent far-field profile of the transmitted mid-IR pulses, showing the pulses undergo self-focusing as they propagate through the active QCL due to the intensity dependent refractive index. The finite-difference time-domain simulations of QCL waveguides with Kerr nonlinearity incorporated show similar behavior to the experimental results. The giant Kerr nonlinearity investigated here may be used to realize ultrafast pulse generation in QCLs. In addition, we temporally resolved the ultrafast mid-infrared transmission modulation of QCLs using a near-infrared pump/mid-infrared probe technique at room temperature. Two different femtosecond wavelength pumps are used with photon energy above and below the quantum well (QW) bandgap. The shorter wavelength pump modulates the mid-infrared probe transmission through interband transition assisted mechanisms, resulting in a high transmission modulation depth

  11. Holographic frequency resolved optical gating for spatio-temporal characterization of ultrashort optical pulse

    NASA Astrophysics Data System (ADS)

    Mehta, Nikhil; Yang, Chuan; Xu, Yong; Liu, Zhiwen

    2014-09-01

    We introduce a novel method for characterizing the spatio-temporal evolution of ultrashort optical field by recording the spectral hologram of frequency resolved optical gating (FROG) trace. We show that FROG holography enables the measurement of phase (up to an overall constant) and group delay of the pulse which cannot be measured by conventional FROG method. To illustrate our method, we perform numerical simulation to generate holographic collinear FROG (cFROG) trace of a chirped optical pulse and retrieve its complex profile at multiple locations as it propagates through a hypothetical dispersive medium. Further, we experimentally demonstrate our method by retrieving a 67 fs pulse at three axial locations in the vicinity of focus of an objective lens and compute its group delay.

  12. Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats.

    PubMed

    Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

    2009-03-30

    We propose theoretically and demonstrate experimentally an optical architecture for flexible Ultra-Wideband pulse generation. It is based on an N-tap reconfigurable microwave photonic filter fed by a laser array by using phase inversion in a Mach-Zehnder modulator. Since a large number of positive and negative coefficients can be easily implemented, UWB pulses fitted to the FCC mask requirements can be generated. As an example, a four tap pulse generator is experimentally demonstrated which complies with the FCC regulation. The proposed pulse generator allows different pulse modulation formats since the amplitude, polarity and time delay of generated pulse is controlled. PMID:19333263

  13. EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

    SciTech Connect

    Strader, M. J.; Mazin, B. A.; Spiro Jaeger, G. V.; Gwinn, C. R.; Meeker, S. R.; Szypryt, P.; Van Eyken, J. C.; Marsden, D.; Walter, A. B.; Ulbricht, G.; Johnson, M. D.; O'Brien, K.; Stoughton, C.; Bumble, B.

    2013-12-10

    We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8% ± 0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.

  14. Quantum paradoxes originating from the nonclassical statistics of physical properties related to each other by half-periodic transformations

    NASA Astrophysics Data System (ADS)

    Hofmann, Holger F.

    2015-06-01

    Quantum paradoxes show that quantum statistics can exceed the limits of positive joint probabilities for physical properties that cannot be measured jointly. It is therefore impossible to describe the relations between the different physical properties of a quantum system by assigning joint realities to their observable values. Instead, recent experimental results obtained by weak measurements suggest that nonclassical correlations could be expressed by complex valued quasiprobabilities, where the phases of the complex probabilities express the action of transformations between the noncommuting properties [H. F. Hofmann, New J. Phys. 13, 103009 (2011), 10.1088/1367-2630/13/10/103009]. In these relations, negative probabilities necessarily emerge whenever the physical properties involved are related to each other by half-periodic transformations, since such transformations are characterized by action phases of π in their complex probabilities. It is therefore possible to trace the failure of realist assumptions back to a fundamental and universally valid relation between statistics and dynamics that associates half-periodic transformations with negative probabilities.

  15. Optical waveguide writing in photochromic material: photoinduced optical properties by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Gutiérrez, J. M.; Camacho-López, S.; Cano-Lara, M.; Rodríguez, A.; Balderas-Navarro, R. E.; Elizalde, L. E.; Ledezma, R.

    2011-09-01

    We report on the interaction of high repetition rate (MHz) Ti: sapphire laser pulses with a spiropyran polymer (MIC1). Such a polymer is photochromic, wich has potential applications in integrated optical devices. A thin film of polymer deposited on a glass substrate is irradiated with ultrashort pulses (66 fs) from a Ti: sapphire laser. We demonstrate that it is possible to induce an absorption band in the visible by the use of femtosecond pulses via a two-photon excitation process; this might be useful to accomplish waveguide-like structures formation with photochromic response.

  16. All-optical optoacoustic microscope based on wideband pulse interferometry.

    PubMed

    Wissmeyer, Georg; Soliman, Dominik; Shnaiderman, Rami; Rosenthal, Amir; Ntziachristos, Vasilis

    2016-05-01

    Optical and optoacoustic (photoacoustic) microscopy have been recently joined in hybrid implementations that resolve extended tissue contrast compared to each modality alone. Nevertheless, the application of the hybrid technique is limited by the requirement to combine an optical objective with ultrasound detection collecting signal from the same micro-volume. We present an all-optical optoacoustic microscope based on a pi-phase-shifted fiber Bragg grating (π-FBG) with coherence-restored pulsed interferometry (CRPI) used as the interrogation method. The sensor offers an ultra-small footprint and achieved higher sensitivity over piezoelectric transducers of similar size. We characterize the spectral bandwidth of the ultrasound detector and interrogate the imaging performance on phantoms and tissues. We show the first optoacoustic images of biological specimen recorded with π-FBG sensors. We discuss the potential uses of π-FBG sensors based on CRPI. PMID:27128047

  17. Dual-Pulse Pulse Position Modulation (DPPM) for Deep-Space Optical Communications: Performance and Practicality Analysis

    NASA Technical Reports Server (NTRS)

    Li, Jing; Hylton, Alan; Budinger, James; Nappier, Jennifer; Downey, Joseph; Raible, Daniel

    2012-01-01

    Due to its simplicity and robustness against wavefront distortion, pulse position modulation (PPM) with photon counting detector has been seriously considered for long-haul optical wireless systems. This paper evaluates the dual-pulse case and compares it with the conventional single-pulse case. Analytical expressions for symbol error rate and bit error rate are first derived and numerically evaluated, for the strong, negative-exponential turbulent atmosphere; and bandwidth efficiency and throughput are subsequently assessed. It is shown that, under a set of practical constraints including pulse width and pulse repetition frequency (PRF), dual-pulse PPM enables a better channel utilization and hence a higher throughput than it single-pulse counterpart. This result is new and different from the previous idealistic studies that showed multi-pulse PPM provided no essential information-theoretic gains than single-pulse PPM.

  18. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle.

    PubMed

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core-shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  19. Picosecond optical vortex pulse illumination forms a monocrystalline silicon needle

    PubMed Central

    Takahashi, Fuyuto; Miyamoto, Katsuhiko; Hidai, Hirofumi; Yamane, Keisaku; Morita, Ryuji; Omatsu, Takashige

    2016-01-01

    The formation of a monocrystalline silicon needle by picosecond optical vortex pulse illumination was demonstrated for the first time in this study. The dynamics of this silicon needle formation was further revealed by employing an ultrahigh-speed camera. The melted silicon was collected through picosecond pulse deposition to the dark core of the optical vortex, forming the silicon needle on a submicrosecond time scale. The needle was composed of monocrystalline silicon with the same lattice index (100) as that of the silicon substrate, and had a height of approximately 14 μm and a thickness of approximately 3 μm. Overlaid vortex pulses allowed the needle to be shaped with a height of approximately 40 μm without any changes to the crystalline properties. Such a monocrystalline silicon needle can be applied to devices in many fields, such as core–shell structures for silicon photonics and photovoltaic devices as well as nano- or microelectromechanical systems. PMID:26907639

  20. Effects of pulse frequency on the microstructure, composition and optical properties of pulsed dc reactively sputtered vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Dong, Xiang; Wu, Zhiming; Jiang, Yadong; Xu, Xiangdong; Yu, He; Gu, Deen; Wang, Tao

    2014-09-01

    Vanadium oxide (VOx) thin films were prepared on unheated glass substrate by pulsed dc reactive magnetron sputtering using different pulse frequency. Field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) measurements were made on the deposited VOx films to characterize the microstructure, composition and optical properties, respectively. It was found that under the same discharge power and argon-oxygen atmosphere, with the increase of pulse frequency, the vertical column-like structure in the films will gradually disappear and the ratio of high-valent VOx to low-valent VOx will obviously elevate. Optical parameters of the VOx films have been obtained by fitting the ellipsometric data (Ψ andΔ) using the Tauc-Lorentz dispersion relation and a multilayer model (air/roughness layer/VOx/glass). The results demonstrated that pulse frequency plays a critical role in determining the transmittance, refractive index, extinction coefficient and optical band gap etc. The correlations between the microstructure, composition, optical properties and pulse frequency are also given by our experiment results. And the mechanisms for the evolution of the microstructure, composition and optical properties with pulse frequency have been discussed. Overall, due to the pulse frequency had a great effect not only on the growth characteristics but also on the optical properties of the VOx films, thus through variation of the pulse frequency during deposition which provide a convenient and efficient approach to control and optimize the performances of the VOx films.

  1. Diffraction leveraged modulation of X-ray pulses using MEMS-based X-ray optics

    DOEpatents

    Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

    2016-08-09

    A method and apparatus are provided for implementing Bragg-diffraction leveraged modulation of X-ray pulses using MicroElectroMechanical systems (MEMS) based diffractive optics. An oscillating crystalline MEMS device generates a controllable time-window for diffraction of the incident X-ray radiation. The Bragg-diffraction leveraged modulation of X-ray pulses includes isolating a particular pulse, spatially separating individual pulses, and spreading a single pulse from an X-ray pulse-train.

  2. Optical pulse propagation in fibers with random dispersion

    NASA Astrophysics Data System (ADS)

    Abdullaev, F. Kh.; Navotny, D. V.; Baizakov, B. B.

    2004-05-01

    The propagation of optical pulses in two types of fibers with randomly varying dispersion is investigated. The first type refers to a uniform fiber dispersion superimposed by random modulations with a zero mean. The second type is the dispersion-managed fiber line with fluctuating parameters of the dispersion map. Application of the mean field method leads to the nonlinear Schrödinger equation (NLSE) with a dissipation term, expressed by a fourth-order derivative of the wave envelope. The prediction of the mean field approach regarding the decay rate of a soliton is compared with that of the perturbation theory based on the inverse scattering transform (IST). A good agreement between these two approaches is found. Possible ways of compensation of the radiative decay of solitons using the linear and nonlinear amplification are explored. The corresponding mean field equation coincides with the complex Swift-Hohenberg equation. The condition for the autosolitonic regime in propagation of optical pulses along a fiber line with fluctuating dispersion is derived and the existence of autosoliton (dissipative soliton) is confirmed by direct numerical simulation of the stochastic NLSE. The dynamics of solitons in optical communication systems with random dispersion-management is further studied applying the variational principle to the mean field NLSE, which results in a system of ODEs for soliton parameters. Extensive numerical simulations of the stochastic NLSE, mean field equation and corresponding set of ODEs are performed to verify the predictions of the developed theory.

  3. Pulsed radiation-induced attenuation in certain optical fibers

    SciTech Connect

    Weiss, J.D. )

    1992-05-01

    Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the pulsed radiation-induced attenuation was measured in two optical fibers considered to be 'nonrad-hard': the 50-micron-core, graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28 krad(Si), respectively. In addition, fits of their post-radiation recovery were made to the geminate recombination model, from which the recombination-rate and generation constants, characteristic of this theory, were determined. These parameters should be useful in determining the response of the fibers to radiation conditions other than those encountered here. 18 refs.

  4. Control of Spectral Phase of Ultrafast Optical Pulses with Grisms

    NASA Astrophysics Data System (ADS)

    Durfee, Charles; Field, Jeff; Squier, Jeff; Kane, Steve

    2008-10-01

    High-quality dispersion management is critical for ultrafast optics. Grisms are a combination of diffraction gratings and prisms. We can use grisms for high-fidelity control of the spectral phase of ultrafast pulses, making systems much more compact and easy to adjust. While the spectral phase of a given system can be obtained with ray-tracing, analytic expressions are desirable for exploring and optimizing new designs. We show that we can analytically calculate the spectral phase of a range of grism-like structures by making a superposition of basic tilted window modules. For example, a prism pair can be described by starting with a tilted slab of glass, which defines the outer edges of the prism pair. The inner edges of the prism pair are then created by superposing a tilted slab of air, which removes glass between the prisms. We will discuss the applications of these grism designs to ultrafast amplifiers and pulse shapers.

  5. Bipolar optical pulse coding for performance enhancement in BOTDA sensors.

    PubMed

    Soto, Marcelo A; Le Floch, Sébastien; Thévenaz, Luc

    2013-07-15

    A pump signal based on bipolar pulse coding and single-sideband suppressed-carried (SSB-SC) modulation is proposed for Brillouin optical time-domain analysis (BOTDA) sensors. Making a sequential use of the Brillouin gain and loss spectra, the technique is experimentally validated using bipolar complementary-correlation Golay codes along a 100 km-long fiber and 2 m spatial resolution, fully resolving a 2 m hot-spot at the end of the sensing fiber with no distortion introduced by the decoding algorithm. Experimental results, in good agreement with the theory, indicate that bipolar Golay codes provide a higher signal-to-noise ratio enhancement and stronger robustness to pump depletion in comparison to optimum unipolar pulse codes known for BOTDA sensing. PMID:23938490

  6. Experimental demonstration of fiber optical parametric chirped-pulse amplification

    NASA Astrophysics Data System (ADS)

    Zhou, Yue; Cheung, Kim K. Y.; Chui, P. C.; Wong, Kenneth K. Y.

    2010-02-01

    A fiber optical parametric chirped-pulse amplifier (FOPCPA) is experimentally demonstrated. A 1.76 ps signal at 1542 nm with a peak power of 20 mW is broadened to 40 ps, and then amplified by a 100-ps pulsed pump at 1560 nm. The corresponding idler at 1578 nm is generated as the FOPCPA output. The same medium used to stretch the signal is deployed to compress the idler to 3.8 ps, and another spool of fiber is deployed to further compress the idler to 1.87 ps. The peak power of the compressed idler is 2 W, which corresponds to a gain of 20 dB.

  7. Suppressing Spectral Diffusion of Emitted Photons with Optical Pulses

    NASA Astrophysics Data System (ADS)

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; Dobrovitski, V. V.

    2016-01-01

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1 ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. Our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.

  8. SOLITONS AND OPTICAL FIBERS: Multiwavelength pulse transmission in an optical fibre — amplifier system

    NASA Astrophysics Data System (ADS)

    Panoiu, N.-C.; Mel'nikov, I. V.; Mihalache, D.; Etrich, C.; Lederer, F.

    2002-11-01

    The structure and dynamics of solitary waves created in the interaction of multiwavelength pulses in a single-mode optical fibre with amplification, filtering, and amplitude modulation is analysed. It is shown that there is a critical wavelength separation between channels above which wavelength-division multiplexing with solitons is feasible and that this separation increases with the number of channels.

  9. Optical Pulse-Shaping for Internal Cooling of Molecular Ions

    NASA Astrophysics Data System (ADS)

    Lien, Chien-Yu; Williams, Scott R.; Odom, Brian

    2011-06-01

    We propose a scheme to use pulse-shaped femtosecond lasers to optically cool the internal degrees of freedom of molecular ions. Since this approach relies on cooling rotational and vibrational quanta by exciting an electronic transition, it is most straightforward for molecular ions with diagonal Frank-Condon-Factors. The scheme has the advantage of requiring only tens of microseconds to reach equilibrium without blackbody radiation to redistribute the population. For AlH+, a candidate species, a rate equation simulation shows equilibrium is achieved in 15 μs.

  10. Self-stabilizing optical clock pulse-train generator using SOA and saturable absorber for asynchronous optical packet processing.

    PubMed

    Nakahara, Tatsushi; Takahashi, Ryo

    2013-05-01

    We propose a novel, self-stabilizing optical clock pulse-train generator for processing preamble-free, asynchronous optical packets with variable lengths. The generator is based on an optical loop that includes a semiconductor optical amplifier (SOA) and a high-extinction spin-polarized saturable absorber (SA), with the loop being self-stabilized by balancing out the gain and absorption provided by the SOA and SA, respectively. The optical pulse train is generated by tapping out a small portion of a circulating seed pulse. The convergence of the generated pulse energy is enabled by the loop round-trip gain function that has a negative slope due to gain saturation in the SOA. The amplified spontaneous emission (ASE) of the SOA is effectively suppressed by the SA, and a backward optical pulse launched into the SOA enables overcoming the carrier-recovery speed mismatch between the SOA and SA. Without external control for the loop gain, a stable optical pulse train consisting of more than 50 pulses with low jitter is generated from a single 10-ps seed optical pulse even with a variation of 10 dB in the seed pulse intensity. PMID:23669927

  11. 5 Hz, >250 mJ Optical Parametric Chirped-Pulse Amplifier at 1053 nm

    SciTech Connect

    Bagnoud, V.; Begishev, I.A.; Guardalben, M.J.; Puth, J.; Zuegel, J.D.

    2005-07-15

    A 250 mJ, 5 Hz repetition rate optical parametric chirped-pulse amplifier with near-Fourier-transform-limited, 430 fs pulses and a beam that can be focused to near the diffraction limit is demonstrated.

  12. Real-time dissipation of optical pulses in passive dielectrics

    SciTech Connect

    Glasgow, S.; Ware, M.

    2009-10-15

    We discuss the inevitable dissipation of energy that must accompany the creation of a pulse-medium excitation state in a passive dielectric. We show that there is a minimum amount of energy that an optical pulse must deposit in the medium to create a given pulse-medium state and that energy deposited beyond this minimum value must be dissipated in the medium. We compare this notion of dissipation to a related concept found by determining the fraction of energy stored in a medium that is irrecoverable by future fields. These two notions of dissipation are model-independent and form upper and lower bounds for real-time loss. Any model-dependent notion of loss that falls outside these bounds has serious conceptual difficulties. We show that a traditional notion of real-time loss based on a multiple-Lorentz oscillator model fails to give reasonable results in classes of passive linear media near EIT, while the notions of loss we introduce give sensible results for all passive media.

  13. Improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors

    NASA Astrophysics Data System (ADS)

    Lai, Haiqiang; Wang, Jianfei; Tu, Xiaobo; Meng, Zhou

    2015-10-01

    An improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors is demonstrated. This scheme uses two series-connected Acoustic-optic modulators (AOMs) as intensity modulator and frequency shifter respectively. Compared to the traditional optical heterodyne demodulation structure, this scheme eliminates the polarization-induced signal fading and the noise floor is lowered for using the Michelson-configuration delay structure and Faraday rotation mirrors (FRMs) in the optic architecture of system. At the same time, the architecture of this scheme is not complicated and can be used to complex a large sensor array. Experimental results show that the phase noise floor of this demodulation scheme is flat and reaches -99dB/sqrt(Hz) at frequencies above 300 Hz.

  14. Construction and characterization of ultraviolet acousto-optic based femtosecond pulse shapers

    SciTech Connect

    Mcgrane, Shawn D; Moore, David S; Greenfield, Margo T

    2008-01-01

    We present all the information necessary for construction and characterization of acousto optic pulse shapers, with a focus on ultraviolet wavelengths, Various radio-frequency drive configurations are presented to allow optimization via knowledgeable trade-off of design features. Detailed performance characteristics of a 267 nm acousto-optic modulator (AOM) based pulse shaper are presented, Practical considerations for AOM based pulse shaping of ultra-broad bandwidth (sub-10 fs) amplified femtosecond pulse shaping are described, with particular attention paid to the effects of the RF frequency bandwidth and optical frequency bandwidth on the spatial dispersion of the output laser pulses.

  15. Pulse-stretched Alexandrite laser for improved optical fiber reliability for laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Simons, David; Koschmann, Eric C.

    1992-06-01

    Clinical data shows that short pulse duration lasers used in laser induced shock wave lithotripsy severely damage optical fibers on both the proximal and distal ends which is unsuitable for clinical use. An Alexandrite laser system has been developed that uses dynamic pulse stretching of the Q-switched laser pulse and improved optical fiber coupling to eliminate the fiber damage. The method of pulse stretching presented controls the laser output pulse energy from 50 to 150 millijoules and temporal shape from 0.5 to 1.5 microseconds. This yields effective fragmentation of calculi without damage to the optical fiber.

  16. Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2003-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

  17. All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-05-01

    Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8dB and reduces its bit error rate to 10-12 at -18dBm.

  18. High-Dynamic-Range Single-Shot Cross-Correlator Based on an Optical Pulse Replicator

    SciTech Connect

    Dorrer, C.; Bromage, J.; Zuegel, J.D.

    2008-09-05

    The operation of a single-shot cross-correlator based on a pulse replicator is described. The correlator uses a discrete sequence of sampling pulses that are nonlinearly mixed with the pulse under test. The combination of a high reflector and partial reflector replicates an optical pulse by multiple internal reflections and generates a sequence of spatially displaced and temporally delayed sampling pulses. This principle is used in a cross-correlator characterizing optical pulses at 1053 nm. A dynamic range higher than 60 dB is obtained over a temporal range larger than 200 ps.

  19. Comparison of pulse propagation and gain saturation characteristics among different input pulse shapes in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Barua, Suchi; Das, Narottam; Nordholm, Sven; Razaghi, Mohammad

    2016-01-01

    This paper presents the pulse propagation and gain saturation characteristics for different input optical pulse shapes with different energy levels in semiconductor optical amplifiers (SOAs). A finite-difference beam propagation method (FD-BPM) is used to solve the modified nonlinear Schrödinger equation (MNLSE) for the simulation of nonlinear optical pulse propagation and gain saturation characteristics in the SOAs. In this MNLSE, the gain spectrum dynamics, gain saturation are taken into account those are depend on the carrier depletion, carrier heating, spectral hole-burning, group velocity dispersion, self-phase modulation and two photon absorption. From this simulation, we obtained the output waveforms and spectra for different input pulse shapes considering different input energy levels. It has shown that the output pulse shape has changed due to the variation of input parameters, such as input pulse shape, input pulse width, and input pulse energy levels. It also shown clearly that the peak position of the output waveforms are shifted toward the leading edge which is due to the gain saturation of the SOA. We also compared the gain saturation characteristics in the SOA for different input pulse shapes.

  20. Generation of unipolar optical pulses in a Raman-active medium

    NASA Astrophysics Data System (ADS)

    Arkhipov, R. M.; Arkhipov, M. V.; Belov, P. A.; Tolmachev, Yu A.; Babushkin, I.

    2016-04-01

    Response of a Raman-active media (RAM) to the excitation by a series of ultrashort (few-cycle) optical pulses propagating at a superluminal velocity is studied theoretically. It is shown that under certain conditions rectangular unipolar pulses (video-pulses) can be generated as the RAM response. The duration, shape and amplitude of these video-pulses can be widely tuned by modifying the pump pulse parameters.

  1. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers.

    PubMed

    Isaienko, Oleksandr; Robel, István

    2016-01-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7-20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ((2)) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations P(NL) of the impulsively excited phonons and those of parametrically amplified waves. PMID:26975881

  2. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Isaienko, Oleksandr; Robel, István

    2016-03-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  3. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    PubMed Central

    Isaienko, Oleksandr; Robel, István

    2016-01-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves. PMID:26975881

  4. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    DOE PAGESBeta

    Isaienko, Oleksandr; Robel, Istvan

    2016-03-15

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to themore » oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. Furthermore, the pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.« less

  5. Two-Photon Optical Pulse Propagation in Sodium Vapor.

    NASA Astrophysics Data System (ADS)

    Rabbani, Syed Golam

    A detailed experimental study of two-photon coherent interaction of short optical pulses with a simple atomic system is carried out. A comparison of experimental results with the theory is also presented. The simple atomic system chosen was sodium vapor. The 3S_{1/2}-3P_ {1/2} transition was used for the one -photon interaction with a two-level system while 3S _{1/2}-3P_{1/2 }-4D_{3/2} transition was used for the two-photon interaction with a three-level system. Pulses from two single-axial-mode dye lasers, pumped synchronously by the second harmonic beam of an injection seeded Nd:YAG laser, propagate co -axially through a pyrex cell containing sodium vapor. The laser beams were focused to a diameter of about 200 μm and typical power was about 10 W, so that maximum intensities of 10^5 W/cm ^2 occurred in the Na cell. The intensity for the experiment was varied by using ND (neutral density) filters. For the two-level one-photon interaction; one of the dye lasers (Rhodamine B) was adjusted such that (lambda_1 = 589.6 nm) it was resonant with the 3S_{1/2} to 3P_{1/2} transition. For the two-photon interaction with the three-level system, the dye lasers were adjusted such that (lambda _1 = 589.6 nm and lambda_2 = 568.3 nm) they were resonant with the 3S _{1/2} to 3P_{1/2 } and 3P_{1/2} to 4D_{3/2} transition. That is lambda_1+lambda_2 were held at the 3S_{1/2} -4D_{3/2} two-photon transition. The wavelength lambda_2 was generated by the second dye laser where Rhodamine 6G was used as the gain medium. After passing through the cell, the laser pulses were focused on an aperture in order to image only a uniform -plane-wave region in the cell. The output of the aperture was then (separately lambda_1 and lambda_2) focused on two fast photodiodes, the output of which were displayed on two storage oscilloscope. The resonance of 3S _{1/2}-3P_{1/2 } transition is confirmed by collecting the D_1 fluorescence (589.6 nm) on a PMT by a fiber cable. Two-photon resonance condition

  6. Lightning Optical Pulse Statistics from Storm Overflights During the Altus Cumulus Electrification Study

    NASA Technical Reports Server (NTRS)

    Mach, D. M.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

    2004-01-01

    The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect time resolved optical pulse data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses. Most of these observations were made while close to the top of the storms. We divided our data into two amplitude groups based on prior NASA U2 aircraft optical data and our pulse characteristics. The group of large pulses with radiance greater than 2.1 mW /sq m sr had mean and median 10 - 10% optical pulse widths of 765 and 735 microns respectively, the 50-50% pulse widths of 396 and 355 microns respectively, and 10-90% rise times of 290 and 260 microns. These values are very similar to the previous U2 based optical results The other group of pulses consisting of slightly more than a quarter of the total pulses observed had radiances less than the minimum values detected in the U2 study. The small pulses were narrower than the large pulses with 5040% mean and median values of 198 and 160 ps respectively. Only 12 % of the flashes contained only small pulses, minimizing the impact of this data on the estimates of detection efficiencies of the orbital instruments, the Lightning Imaging Sensor and Optical Transient Detector.

  7. Fabrication of optical cavities with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jintian; Song, Jiangxin; Tang, Jialei; Fang, Wei; Sugioka, Koji; Cheng, Ya

    2014-03-01

    We report on fabrication of three-dimensional (3D) high-quality (Q) whispering-gallery-mode microcavities by femtosecond laser micromachining. The main fabrication procedures include the formation of on-chip freestanding microdisk through selective material removal by femtosecond laser pulses, followed by surface smoothing processes (CO2 laser reflow for amorphous glass and focused ion beam (FIB) sidewall milling for crystalline materials) to improve the Q factors. Fused silica microcavities with 3D geometries are demonstrated with Q factors exceeding 106. A microcavity laser based on Nd:glass has been fabricated, showing a threshold as low as 69μW via free space continuous-wave optical excitation at the room temperature. CaF2 crystalline microcavities with Q factor of ~4.2×104 have also been demonstrated. This technique allows us to fabricate 3D high-Q microcavities in various transparent materials such as glass and crystals, which will benefit a broad spectrum of applications such as nonlinear optics, quantum optics, and bio-sensing.

  8. Optical Response of Metal Nanoantennas to Femtosecond Pulses

    NASA Astrophysics Data System (ADS)

    Biswas, Sushmita; Heberle, Albert

    2007-03-01

    Nanoscale metal antennas are promising devices for focusing light down to dimensions much smaller than the wavelength of light. This focusing can lead to strong optical enhancement of the response of single molecules or quantum dots placed in the antenna gap, as well as strong nonlinearities. The optical response of such antenna, however, is not well understood yet. Here, we will present results of our investigations of the linear and nonlinear optical response of silver nanoscale bowtie antennas to excitation with near-infrared pulses from a femtosecond Ti:sapphire laser. The antennas were fabricated with electron beam lithography and a lift-of process on glass substrates and semiconductor materials. They have lengths of a few hundred nanometers and gaps between 10 and 100 nanometers. We will discuss polarization dependence of the excitation sensitivity, second harmonic generation and other nonlinear effects. References: [1] P. Muhlschlegel et al., Science ,1607(2005). [2] J.N. Farahani et al., Phys. Rev. Lett. 95,017402(2005).

  9. Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating

    SciTech Connect

    DeLong, K.W.; Ladera, C.L.; Trebino, R.; Kohler, B.; Wilson, K.R.

    1995-03-01

    Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms.

  10. Pulsed photothermal radiometry in optically transparent media containing discrete optical absorbers.

    PubMed

    Vitkin, I A; Wilson, B C; Anderson, R R; Prahl, S A

    1994-10-01

    A description of heat transport by conduction and radiation in inhomogeneous materials following absorption of a brief optical pulse is presented, and investigated experimentally using pulsed photothermal radiometry (PPTR). The model indicates that the role of radiation as an intramedium heat transfer modality increases with increasing temperatures and decreasing infrared (IR) absorption of the medium. However, for the range of conditions analysed in this study, conductive transfer dominates. Thus, the inclusion of radiation does not significantly perturb the internal temperature profiles, although it does influence the radiometric emission from the sample, and hence the PPTR signal. The thermal confinement effects described in this study may be relevant in photomedicine, for example in pulsed laser irradiation of tissues containing small absorbing targets. PMID:15551541

  11. Pulse compression by nonlinear pulse evolution with reduced optical wave breaking in erbium-doped fiber amplifiers.

    PubMed

    Tamura, K; Nakazawa, M

    1996-01-01

    Nonlinear pulse evolution is studied for a fiber with normal dispersion (ND) and gain. Numerical simulations show that under certain conditions the pulse evolves into a parabolic shape, which has been shown to reduce optical wave breaking. Much as with the square pulse that forms in passive fibers with ND, the interplay of ND and self-phase modulation creates a highly linear chirp, which can be efficiently compressed. Application to an amplifying fiber/grating (prism) pair pulse compressor is considered, with an experimental demonstration of compression from 350 to 77 fs at a gain of 18 dB in an erbium-doped fiber amplifier. PMID:19865307

  12. THz generation from optical rectification tilted-pulse-front pumping scheme with laser pulse focused to a line

    NASA Astrophysics Data System (ADS)

    Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko

    2015-10-01

    In this study, we investigate THz pulses generated from optical rectification with tilted-pulse-front pumping scheme in which the laser beam is focused to a line in a stoichiometric lithium niobate (sLN) crystal. A cylindrical lens and a common lens are used to focus the pump laser beam to a line. The power law of THz pulse generation and the redshift induced from the sLN crystal are measured. The spectral shapes of the laser pulse are changed by inserting a filter into the pump laser beam, causing the THz radiation to change. The filter is a metal wire with 2 mm diameter. Experimental results show that this method can change the generated THz time waveforms but not their spectra. Such method offers a simple means to change and manipulate THz field generated from optical rectification with tiled-pulse-front pumping scheme.

  13. Directly driven source of multi-gigahertz, sub-picosecond optical pulses

    SciTech Connect

    Messerly, Michael J.; Dawson, Jay W.; Barty, Christopher P.J.; Gibson, David J.; Prantil, Matthew A.; Cormier, Eric

    2015-10-20

    A robust, compact optical pulse train source is described, with the capability of generating sub-picosecond micro-pulse sequences, which can be periodic as well as non-periodic, and at repetition rates tunable over decades of baseline frequencies, from MHz to multi-GHz regimes. The micro-pulses can be precisely controlled and formatted to be in the range of many ps in duration to as short as several fs in duration. The system output can be comprised of a continuous wave train of optical micro-pulses or can be programmed to provide gated bursts of macro-pulses, with each macro-pulse consisting of a specific number of micro-pulses or a single pulse picked from the higher frequency train at a repetition rate lower than the baseline frequency. These pulses could then be amplified in energy anywhere from the nJ to MJ range.

  14. Soft X-Ray Optics by Pulsed Laser Deposition

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E.

    1996-01-01

    Mo/Si and C/Co multilayers for soft x-ray optics were designed for spectral regions of interest in possible applications. Fabrication was effected by Pulsed Laser Deposition using Nd:YAG (355 nm) or excimer (248 nm) lasers in order to evaluate the suitability of this technique. Results for Mo/Si structures were not considered satisfactory due mainly to problems with particulate production and target surface modification during Si ablation. These problems may be alleviated by a two-wavelength approach, using separate lasers for each target. Results for C/Co multilayers are much more encouraging, since indication of good layering was observed for extremely thin layers. We expect to continue investigating this possibility. In order to compete with traditional PVD techniques, it is necessary to achieve film coverage uniformity over large enough areas. It was shown that this is feasible, and novel means of achieving it were devised.

  15. Detection alternatives for pulse position modulation (PPM) optical communication

    NASA Astrophysics Data System (ADS)

    Mecherle, G. Stephen

    1986-01-01

    An analysis is conducted for alternative optical communication detection strategies employing pulse position modulation (PPM). In cases without error correcting codes, the M-ary maximum count strategy is noted to furnish the best performance on the basis of its maximum a posteriori character. In cases with error correcting codes, the decoder has the additional option of hard or soft decisioning and each of the unencoded detection schemes can interface directly with a hard decision decoder. Illustrative hard decision coding gains are evaluated for M-ary Reed-Solomon and binary BCH codes with an APD receiver. The performance of rate-1/2 Reed-Solomon codes is compared for Delta-max and threshold soft decision strategies with an APD receiver.

  16. Adaptive optics for ultra short pulsed lasers in UHV environment

    NASA Astrophysics Data System (ADS)

    Deneuville, Francois; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-02-01

    ISP SYSTEM has developed an electro-mechanical deformable mirror compatible with Ultra High Vacuum environment, suitable for ultra short pulsed lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations. μ-AME actuators are driven by stepper motors, and their patented special design allows controlling the force with a very high accuracy. Materials and assembly method have been adapted to UHV constraints and the performances were evaluated on a first application for a beam with a diameter of 250mm. A Strehl ratio above 0.9 was reached for this application. Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for standard MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The deformable mirror design allows changing easily an actuator or even the membrane if needed, in order to improve the facility availability. They are designed for circular, square or elliptical aperture from 30mm up to 500mm or more, with incidence angle from 0° to 45°. They can be equipped with passive or active cooling for high power lasers with high repetition rate.

  17. Soft x ray optics by pulsed laser deposition

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E.

    1994-01-01

    A series of molybdenum thin film depositions by PLD (Pulsed Laser Deposition) have been carried out, seeking appropriate conditions for multilayer fabrication. Green (532 nm) and UV (355 nm) light pulses, in a wide range of fluences, were used. Relatively large fluences (in comparison with Si) are required to cause evaporation of molybdenum. The optical penetration depths and reflectivities for Mo at these two wavelengths are comparable, which means that results should be, and do appear to be similar for equal fluences. For all fluences above threshold used, a large number of incandescent particles is ejected by the target (either a standard Mo sputtering target or a Mo sheet were tried), together with the plasma plume. Most of these particles are clearly seen to bounce off the substrate. The films were observed with light microscopy using Nomarski and darkfield techniques. There is no evidence of large debris. Smooth films plus micron-sized droplets are usually seen. The concentration of these droplets embedded in the film appears not to vary strongly with the laser fluence employed. Additional characterization with SEM and XRD is under way.

  18. Suppressing spectral diffusion of emitted photons with optical pulses

    DOE PAGESBeta

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; Dobrovitski, V. V.

    2016-01-22

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1more » ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.« less

  19. Deformation of ultra-short laser pulses by optical systems for laser scanners.

    PubMed

    Büsing, Lasse; Bonhoff, Tobias; Gottmann, Jens; Loosen, Peter

    2013-10-21

    Current experiments of processing glass with ultra-short laser pulses (< 1 ps) lead to scan angle depending processing results. This scan angle depending effect is examined by simulations of a common focusing lens for laser scanners. Due to dispersion, focusing lenses may cause pulse deformations and increase the pulse duration in the focal region. If the field angle of the incoming laser beam is variable, the pulse deformation may also vary as a function of the field angle. By ray tracing as well as wave optical simulations we investigate pulse deformations of optical systems for different scan angles. PMID:24150292

  20. Nonlinear optics with phase-controlled pulses in the sub-two-cycle regime.

    PubMed

    Morgner, U; Ell, R; Metzler, G; Schibli, T R; Kärtner, F X; Fujimoto, J G; Haus, H A; Ippen, E P

    2001-06-11

    Nonlinear optical effects due to the phase between carrier and envelope are observed with 5 fs pulses from a Kerr-lens mode-locked Ti:sapphire laser. These sub-two-cycle pulses with octave spanning spectra are the shortest pulses ever generated directly from a laser oscillator. Detection of the carrier-envelope phase slip is made possible by simply focusing the short pulses directly from the oscillator into a BBO crystal. As a further example of nonlinear optics with such short pulses, the interference between second- and third-harmonic components is also demonstrated. PMID:11415276

  1. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    NASA Astrophysics Data System (ADS)

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing; Ding, Dajun

    2013-10-01

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  2. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  3. Nonlinear Optics with Phase-Controlled Pulses in the Sub-Two-Cycle Regime

    SciTech Connect

    Morgner, U.; Ell, R.; Metzler, G.; Schibli, T. R.; Kartner, F. X.; Fujimoto, J. G.; Haus, H. A.; Ippen, E. P.

    2001-06-11

    Nonlinear optical effects due to the phase between carrier and envelope are observed with 5fs pulses from a Kerr-lens mode-locked Ti:sapphire laser. These sub-two-cycle pulses with octave spanning spectra are the shortest pulses ever generated directly from a laser oscillator. Detection of the carrier-envelope phase slip is made possible by simply focusing the short pulses directly from the oscillator into a BBO crystal. As a further example of nonlinear optics with such short pulses, the interference between second- and third-harmonic components is also demonstrated.

  4. Composite pulses for high-fidelity population inversion in optically dense, inhomogeneously broadened atomic ensembles

    NASA Astrophysics Data System (ADS)

    Demeter, Gabor

    2016-02-01

    We derive composite pulse sequences that achieve high-fidelity excitation of two-state systems in an optically dense, inhomogeneously broadened ensemble. The composite pulses are resistant to distortions due to the backaction of the medium they propagate in and are able to create high-fidelity inversion to optical depths α z >10 . They function well with smooth pulse shapes used for coherent control of optical atomic transitions in quantum computation and communication. They are an intermediary solution between single π -pulse excitation schemes and adiabatic passage schemes, being far more error tolerant than the former but still considerably faster than the latter.

  5. Impact of High-Frequency Spectral Phase Modulation on the Temporal Profile of Short Optical Pulses

    SciTech Connect

    Dorrer, C.; Bromage, J.

    2008-03-18

    The impact of high-frequency spectral phase modulation on the temporal intensity of optical pulses is derived analytically and simulated in two different regimes. The temporal contrast of an optical pulse close to the Fourier-transform limit is degraded by a pedestal related to the power spectral density of the spectral phase modulation. When the optical pulse is highly chirped, its intensity modulation is directly related to the spectral phase variations with a transfer function depending on the second-order dispersion of the chirped pulse. The metrology of the spectral phase of an optical pulse using temporal-intensity measurements performed after chirping the pulse is studied. The effect of spatial averaging is also discussed.

  6. Characterization of Ultrafast Laser Pulses using a Low-dispersion Frequency Resolved Optical Grating Spectrometer

    NASA Astrophysics Data System (ADS)

    Whitelock, Hope; Bishop, Michael; Khosravi, Soroush; Obaid, Razib; Berrah, Nora

    2016-05-01

    A low dispersion frequency-resolved optical gating (FROG) spectrometer was designed to characterize ultrashort (<50 femtosecond) laser pulses from a commercial regenerative amplifier, optical parametric amplifier, and a home-built non-colinear optical parametric amplifier. This instrument splits a laser pulse into two replicas with a 90:10 intensity ratio using a thin pellicle beam-splitter and then recombines the pulses in a birefringent medium. The instrument detects a wavelength-sensitive change in polarization of the weak probe pulse in the presence of the stronger pump pulse inside the birefringent medium. Scanning the time delay between the two pulses and acquiring spectra allows for characterization of the frequency and time content of ultrafast laser pulses, that is needed for interpretation of experimental results obtained from these ultrafast laser systems. Funded by the DoE-BES, Grant No. DE-SC0012376.

  7. Nonlinear-microscopy optical-pulse sources based on mode-locked semiconductor lasers.

    PubMed

    Yokoyama, H; Sato, A; Guo, H-C; Sato, K; Mure, M; Tsubokawa, H

    2008-10-27

    We developed picosecond optical-pulse sources suitable for multiphoton microscopy based on mode-locked semiconductor lasers. Using external-cavity geometry, stable hybrid mode locking was achieved at a repetition rate of 500 MHz. Semiconductor optical amplifiers driven by synchronized electric pulses reached subharmonic optical-pulse repetition rates of 1-100 MHz. Two-stage Yb-doped fiber amplifiers produced optical pulses of 2 ps duration, with a peak power of a few kilowatts at a repetition rate of 10 MHz. These were employed successfully for nonlinear-optic bio-imaging using two-photon fluorescence, second-harmonic generation, and sum-frequency generation of synchronized two-color pulses. PMID:18958056

  8. Damage-resistant single-pulse optics for x-ray free electron lasers

    SciTech Connect

    Hau-Riege, S; London, R; Bogan, M; Chapman, H; Bergh, M

    2007-04-27

    Short-pulse ultraviolet and x-ray free electron lasers of unprecedented peak brightness are in the process of revolutionizing physics, chemistry, and biology. Optical components for these new light sources have to be able to withstand exposure to the extremely high-fluence photon pulses. Whereas most optics have been designed to stay intact for many pulses, it has also been suggested that single-pulse optics that function during the pulse but disintegrate on a longer timescale, may be useful at higher fluences than multiple-pulse optics. In this paper we will review damage-resistant single-pulse optics that recently have been demonstrated at the FLASH soft-x-ray laser facility at DESY, including mirrors, apertures, and nanolenses. It was found that these objects stay intact for the duration of the 25-fs FLASH pulse, even when exposed to fluences that exceed the melt damage threshold by fifty times or more. We present a computational model for the FLASH laser-material interaction to analyze the extent to which the optics still function during the pulse. Comparison to experimental results obtained at FLASH shows good quantitative agreement.

  9. Synthesis of Optical Frequencies and Ultrastable Femtosecond Pulse Trains from an Optical Reference Oscillator

    NASA Astrophysics Data System (ADS)

    Bartels, A.; Ramond, T. M.; Diddams, S. A.; Hollberg, L.

    Recently, atomic clocks based on optical frequency standards have been demonstrated [1,2]. A key element in these clocks is a femtosecond laser that downconverts the petahertz oscillation rate into countable ticks at 1 GHz. When compared to current microwave standards, these new optical clocks are expected to yield an improvement in stability and accuracy by roughly a factor of 1000. Furthermore, it is possible that the lowest noise microwave sources will soon be based on atomically-stabilized optical oscillators that have their frequency converted to the microwave domain via a femtosecond laser. Here, we present tests of the ability of femtosecond lasers to transfer stability from an optical oscillator to their repetition rates as well as to the associated broadband frequency comb. In a first experiment, we phase-lock two lasers to a stabilized laser diode and find that the relative timing jitter in their pulse trains can be on the order of 1 femtosecond in a 100 kHz bandwidth. It is important to distinguish this technique from previous work where a femtosecond laser has been stabilized to a microwave standard [3,4] or another femtosecond laser [5]. Furthermore, we extract highly stable microwave signals with a fractional frequency instability of 2×10-14 in 1 s by photodetection of the laser pulse trains. In a second experiment, we similarly phase-lock the femtosecond laser to an optical oscillator with linewidth less than 1 Hz [6]. The precision with which we can make the femtosecond frequency comb track this reference oscillator is then tested by a heterodyne measurement between a second stable optical oscillator and a mode of the frequency comb that is displaced 76 THz from the 1 Hz-wide reference. From this heterodyne signal we place an upper limit of 150 Hz on the linewidth of the elements of the frequency comb, limited by the noise in the measurement itself.

  10. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  11. Electron optical injection with head-on and countercrossing colliding laser pulses.

    PubMed

    Kotaki, H; Daito, I; Kando, M; Hayashi, Y; Kawase, K; Kameshima, T; Fukuda, Y; Homma, T; Ma, J; Chen, L-M; Esirkepov, T Zh; Pirozhkov, A S; Koga, J K; Faenov, A; Pikuz, T; Kiriyama, H; Okada, H; Shimomura, T; Nakai, Y; Tanoue, M; Sasao, H; Wakai, D; Matsuura, H; Kondo, S; Kanazawa, S; Sugiyama, A; Daido, H; Bulanov, S V

    2009-11-01

    A high stability electron bunch is generated by laser wakefield acceleration with the help of a colliding laser pulse. The wakefield is generated by a laser pulse; the second laser pulse collides with the first pulse at 180 degrees and at 135 degrees realizing optical injection of an electron bunch. The electron bunch has high stability and high reproducibility compared with single pulse electron generation. In the case of 180 degrees collision, special measures have been taken to prevent damage. In the case of 135 degrees collision, since the second pulse is countercrossing, it cannot damage the laser system. PMID:20365929

  12. Electron Optical Injection with Head-On and Countercrossing Colliding Laser Pulses

    SciTech Connect

    Kotaki, H.; Daito, I.; Kando, M.; Hayashi, Y.; Kawase, K.; Kameshima, T.; Fukuda, Y.; Homma, T.; Ma, J.; Chen, L.-M.; Esirkepov, T. Zh.; Pirozhkov, A. S.; Koga, J. K.; Kiriyama, H.; Okada, H.; Shimomura, T.; Nakai, Y.; Tanoue, M.; Sasao, H.; Wakai, D.

    2009-11-06

    A high stability electron bunch is generated by laser wakefield acceleration with the help of a colliding laser pulse. The wakefield is generated by a laser pulse; the second laser pulse collides with the first pulse at 180 deg. and at 135 deg. realizing optical injection of an electron bunch. The electron bunch has high stability and high reproducibility compared with single pulse electron generation. In the case of 180 deg. collision, special measures have been taken to prevent damage. In the case of 135 deg. collision, since the second pulse is countercrossing, it cannot damage the laser system.

  13. Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement

    SciTech Connect

    Liu, Yun; Huang, Chunning; Aleksandrov, Alexander V

    2013-01-01

    We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

  14. Reconfigurable symmetric pulses generation using on-chip cascaded optical differentiators.

    PubMed

    Hou, Jie; Dong, Jianji; Zhang, Xinliang

    2016-09-01

    We report a type of programmable pulse shaping method based on cascaded frequency-detuned optical differentiators. By properly adjusting the central wavelength of each differentiator, a large variety of symmetric pulses can be generated from a transform-limited Gaussian-like pulse. We numerically and experimentally demonstrate the generation of flat-top, parabolic and triangular pulses with tunable pulse widths from a 20-ps Gaussian-like pulse, using no more than three cascaded differentiators. It can be found that as more differentiators are used, higher synthesized accuracy and larger tuning range of pulse widths can be obtained in general. Additionally, in our experiment, we design and fabricate thermally tunable delay interferometers on the silicon-on-insulator (SOI) platform to work as optical differentiators, which can help us realize the shaping system with small footprint (943μm × 395μm) and high stability. PMID:27607657

  15. Amplification of frequency-modulated soliton-like pulses in inhomogeneous optical waveguides with normal dispersion

    NASA Astrophysics Data System (ADS)

    Zolotovskii, I. O.; Novikov, S. G.; Okhotnikov, O. G.; Sementsov, D. I.; Yavtushenko, I. O.; Yavtushenko, M. S.

    2012-06-01

    The possibility of effective amplification of self-similar frequency-modulated pulses (FMPs) in longitudinally inhomogeneous active optical waveguides is studied. Peculiarities of the dynamics of parabolic pulses with a constant frequency modulation rate are considered. An optimal profile of variation of the group velocity dispersion was obtained in correspondence with optimal amplification of a similariton-like pulse. The use of FMPs in amplifying and longitudinally inhomogeneous optical waveguides with a correspondingly matched profile of normal dispersion of group velocities is shown to be capable of providing for an amplification of subpicosecond pulses up to energies above 1 nJ.

  16. Broadband noise limit in the photodetection of ultralow jitter optical pulses.

    PubMed

    Sun, Wenlu; Quinlan, Franklyn; Fortier, Tara M; Deschenes, Jean-Daniel; Fu, Yang; Diddams, Scott A; Campbell, Joe C

    2014-11-14

    Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption on the photocurrent noise of high-speed photodiodes when detecting ultralow jitter optical pulses. Despite its small contribution to the total photocurrent, this excess noise can determine the phase noise and timing jitter of microwave signals generated by detecting ultrashort optical pulses. A Monte Carlo simulation of the photodetection process is used to quantitatively estimate the excess noise. Simulated phase noise on the 10 GHz harmonic of a photodetected pulse train shows good agreement with previous experimental data, leading to the conclusion that the lowest phase noise photonically generated microwave signals are limited by photocarrier scattering well above the quantum limit of the optical pulse train. PMID:25432042

  17. Optical polarizing neutron devices designed for pulsed neutron sources

    SciTech Connect

    Takeda, M.; Kurahashi, K.; Endoh, Y.; Itoh, S.

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  18. Line-by-line pulse shaping control for optical arbitrary waveform generation.

    PubMed

    Jiang, Z; Leaird, D E; Weiner, A M

    2005-12-12

    We demonstrate a fundamental operation for generating complex waveforms in the optical domain - line-by-line pulse shaping control for optical arbitrary waveform generation (O-AWG). Independent manipulation of the spectral amplitude and phase of individual lines from a mode-locked frequency comb, or spectral line-by-line pulse shaping, leads to synthesis of user-specified ultrafast optical waveforms with unprecedented control. Coupled with recent advances in frequency stabilized mode-locked lasers, line-by-line pulse shaping control should have significant impact to fields drawing upon developments in the field of ultrafast science. PMID:19503258

  19. Electromagnetically induced transparency in rubidium vapor prepared by a comb of short optical pulses

    SciTech Connect

    Sautenkov, Vladimir A.; Rostovtsev, Yuri V.; Ye, C.Y.; Welch, George R.; Kocharovskaya, Olga; Scully, Marlan O.

    2005-06-15

    It was shown by Kocharovskaya and Khanin [Sov. Phys. JETP 63, 945 (1986)] that a comb of optical pulses can induce a ground-state atomic coherence and change the optical response of an atomic medium. In our experiment, we studied the propagation of a comb of optical pulses produced by a mode-locked diode laser in rubidium atomic vapor. Electromagnetically induced transparency (EIT) was observed when the pulse repetition rate is a subharmonic of the hyperfine splitting of the ground state. The width of the EIT resonance is determined by the relaxation rate of the ground-state coherence. Possible applications to magnetometery, atomic clocks, and frequency chains are discussed.

  20. Soliton Solutions for High-Bandwidth Optical Pulse Storage and Retrieval

    NASA Astrophysics Data System (ADS)

    Groves, Elizabeth

    Quantum-optical information processing in material systems requires on-demand manipulation and precision control techniques. Previous implementations of optical pulse control have mostly been limited to weak, narrowband probe fields, often using a modified form of Electromagnetically Induced Transparency (EIT). We propose optical pulse control in a contrasting regime with high-bandwidth optical pulses, enabling higher clock-rates and on-demand fast pulse switching. Our novel solutions exploit the coherent interaction between short, strong pulses and resonant media (such as a cloud of ultra-cold atoms) to store, manipulate, and retrieve high-bandwidth optical pulse information. The evolution equations that model such short pulse propagation are inherently nonlinear and they govern both amplitudes and phases of the propagating field and the dielectric medium. They cannot be modeled by population rate equations or simplified with steady-state assumptions. Nonlinear evolution equations do not yield solutions easily and using them to characterize the physics at hand typically requires complementary analytical and numerical approaches. We take both approaches here, using analytical methods and our own numerical integration code. For uniform and infinitely extended media we generate novel three-pulse soliton solutions: robust, nonlinear waves with the unique property of preserving their shape under interaction (or "collision"). This important property enables one high-bandwidth soliton to push another from one location in an atomic cloud to another, predictably and nondestructively. We then also probe the practical utility of our specialized infinite-extent solutions by numerically solving the same nonlinear evolution equations for a variety of initial pulse shapes and strengths. Our numerical simulations confirm that our novel soliton solutions provide appropriate control parameters, including pulse storage locations and pulse sequencing, even in finite media under non

  1. Generation of optical pulse packet using a fiber stacker for time fiducial applications

    NASA Astrophysics Data System (ADS)

    Lin, Honghuan; Wang, Jianjun; Huang, Zhihua; Li, Qi; Xu, Lixin; Tang, Xuan; Li, Chengyu; Guo, Chao; Zhao, Pengfei; Jing, Feng

    2016-08-01

    We present the concept of multicolor optical pulse packet generation based on modified fiber stackers featured with reflection geometries. Infrared radiation, visible and ultraviolet time fiducials were obtained by the amplification and frequency-conversion of the pulse packet generated in this fiber stacker. Application for the inertial confinement fusion (ICF) experiment diagnosis with time fiducials was demonstrated. With featured reflection geometries, the shaped packet pulses with uniform sub-pulse polarization states in a temporal window of ns range were generated in the fiber stacker. The design greatly simplifies the packet pulse generation for time fiducial and could be used for laser-driven ICF experimental diagnosis.

  2. Numerical solutions of Maxwell's equations for nonlinear-optical pulse propagation

    NASA Astrophysics Data System (ADS)

    Hile, Cheryl V.; Kath, William L.

    1996-06-01

    A model and numerical solutions of Maxwell's equations describing the propagation of short, solitonlike pulses in nonlinear dispersive optical media are presented. The model includes linear dispersion expressed in the time domain, a Kerr nonlinearity, and a coordinate system moving with the group velocity of the pulse. Numerical solutions of Maxwell's equations are presented for circularly polarized and linearly polarized electromagnetic fields. When the electromagnetic fields are assumed to be circularly polarized, numerical solutions are compared directly with solutions of the nonlinear Schrodinger (NLS) equation. These comparisons show good agreement and indicate that the NLS equation provides an excellent model for short-pulse propagation. When the electromagnetic fields are assumed to be linearly polarized, the propagation of daughter pulses, small-amplitude pulses at three times the frequency of the solitonlike pulse, are observed in the numerical solution. These daughter pulses are shown to be the direct result of third harmonics generated by the main, solitonlike, pulse.

  3. Pulsed laser manipulation of an optically trapped bead: averaging thermal noise and measuring the pulsed force amplitude.

    PubMed

    Lindballe, Thue B; Kristensen, Martin V G; Berg-Sørensen, Kirstine; Keiding, Søren R; Stapelfeldt, Henrik

    2013-01-28

    An experimental strategy for post-eliminating thermal noise on position measurements of optically trapped particles is presented. Using a nanosecond pulsed laser, synchronized to the detection system, to exert a periodic driving force on an optically trapped 10 μm polystyrene bead, the laser pulse-bead interaction is repeated hundreds of times. Traces with the bead position following the prompt displacement from equilibrium, induced by each laser pulse, are averaged and reveal the underlying deterministic motion of the bead, which is not visible in a single trace due to thermal noise. The motion of the bead is analyzed from the direct time-dependent position measurements and from the power spectrum. The results show that the bead is on average displaced 208 nm from the trap center and exposed to a force amplitude of 71 nanoNewton, more than five orders of magnitude larger than the trapping forces. Our experimental method may have implications for microrheology. PMID:23389179

  4. Experimental study of electro-optical Q-switched pulsed Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    A, Maleki; M Kavosh, Tehrani; H, Saghafifar; M, H. Moghtader Dindarlu

    2016-03-01

    We report the specification of a compact and stable side diode-pumped Q-switched pulsed Nd:YAG laser. We experimentally study and compare the performance of the pulsed Nd:YAG laser in the free-running and Q-switched modes at different pulse repetition rates from 1 Hz to 100 Hz. The laser output energy is stabilized by using a special configuration of the optical resonator. In this laser, an unsymmetrical concave-concave resonator is used and this structure helps the mode volume to be nearly fixed when the pulse repetition rate is increased. According to the experimental results in the Q-switched operation, the laser output energy is nearly constant around 70 mJ with an FWHM pulse width of 7 ns at 100 Hz. The optical-to-optical conversion efficiency in the Q-switched regime is 17.5%.

  5. Pump-seed synchronization for MHz repetition rate, high-power optical parametric chirped pulse amplification.

    PubMed

    Fattahi, Hanieh; Teisset, Catherine Yuriko; Pronin, Oleg; Sugita, Atsushi; Graf, Roswitha; Pervak, Vladimir; Gu, Xun; Metzger, Thomas; Major, Zsuzsanna; Krausz, Ferenc; Apolonski, Alexander

    2012-04-23

    We report on an active synchronization between two independent mode-locked lasers using a combined electronic-optical feedback. With this scheme, seed pulses at MHz repetition rate were amplified in a non-collinear optical parametric chirped pulse amplifier (OPCPA). The amplifier was seeded with stretched 1.5 nJ pulses from a femtosecond Ti:Sapphire oscillator, while pumped with the 1 ps, 2.9 µJ frequency-doubled output of an Yb:YAG thin-disk oscillator. The residual timing jitter between the two oscillators was suppressed to 120 fs (RMS), allowing for an efficient and broadband amplification at 11.5 MHz to a pulse energy of 700 nJ and an average power of 8 W. First compression experiment with 240 nJ amplified pulse energy resulted in a pulse duration of ~10 fs. PMID:22535076

  6. Existence and stability of N-pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Sandstede, B.; Jones, C. K. R. T.; Alexander, J. C.

    1997-02-01

    The propagation of pulses in optical communication systems in which attenuation is compensated by phase-sensitive amplifiers is investigated. A central issue is whether optical fibers are capable of carrying several pieces of information at the same time. In this paper, multiple pulses are shown to exist for a fourth-order nonlinear diffusion model due to Kutz and co-workers (1994). Moreover, criteria are derived for determining which of these pulses are stable. The pulses arise in a reversible orbit-flip, a homoclinic bifurcation investigated here for the first time. Numerical simulations are used to study multiple pulses far away from the actual bifurcation point. They confirm that properties of the multiple pulses including their stability are surprisingly well-predicted by the analysis carried out near the bifurcation.

  7. Effect of noise on Frequency-Resolved Optical Gating measurements of ultrashort pulses

    SciTech Connect

    Fittinghoff, D.N.; DeLong, K.W.; Ladera, C.L.; Trebino, R.

    1995-02-01

    We study the effects of noise in Frequency-Resolved Optical Gating measurements of ultrashort pulses. We quantify the measurement accuracy in the presence of additive, muliplicative, and quantization noise, and discuss filtering and pre-processing of the data.

  8. Design of pulse stretching cell for a sodium guide star optical system

    SciTech Connect

    Friedman, H.W.; Horton, J.A.; Kuklo, T.J.; Wong, N.J.

    1992-11-10

    A pulse stretcher has been designed for the LLNL sodium guide star experiment to lower the laser flux and avoid saturation effects. The optical design, mechanical layout and wavefront error analysis are presented.

  9. A Multiterawatt Laser Using a High-Contrast, Optical Parametric Chirped-Pulse Presamplifier

    SciTech Connect

    Bagnoud, V.; Puth, J.; Begishev, I.; Guardalben, M.; Zuegel, J.D.; Forget, N.; LeBlanc, C.

    2005-09-30

    A laser has been built that uses optical parametric chirped-pulse preamplification and a glass booster amplifier. We review the performance of the 5-Hz, multijoule OPCPA pump laser, the 370-mJ OPCPA, and the overall laser.

  10. All-Optical Generation and Switching of Few-Cycle Millimeter-Wave Pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jim-Wein; Wun, Jhih-Min; Shi, Jin-Wei; Pan, Ci-Ling

    2014-10-01

    We conducted a comparative study of two schemes of photonic generation and switching of few-cycle sub-THz or millimeter wave (MMW) pulses by use of a photonic-transmitter-mixer (PTM) module with a broadband and high-power near-ballistic uni-traveling carrier photodiode (NBUTC-PD). In the first scheme, we performed all-optical ultra-fast switching (bias modulation) of the PTM injected with a 93 GHz optical local-oscillator signal. Sub-2-cycle short MMW pulses with central frequency at 93 GHz were generated. To compare, in scheme 2, we employed femtosecond optical short pulses to directly excite the PTM under a DC bias (optical modulation). The former approach is shown to be capable of providing much less signal distortion and much shorter pulse duration than the latter.

  11. Active lamp pulse driver circuit. [optical pumping of laser media

    NASA Technical Reports Server (NTRS)

    Logan, K. E. (Inventor)

    1983-01-01

    A flashlamp drive circuit is described which uses an unsaturated transistor as a current mode switch to periodically subject a partially ionized gaseous laser excitation flashlamp to a stable, rectangular pulse of current from an incomplete discharge of an energy storage capacitor. A monostable multivibrator sets the pulse interval, initiating the pulse in response to a flash command by providing a reference voltage to a non-inverting terminal of a base drive amplifier; a tap on an emitter resistor provides a feedback signal sensitive to the current amplitude to an inverting terminal of amplifier, thereby controlling the pulse amplitude. The circuit drives the flashlamp to provide a squarewave current flashlamp discharge.

  12. Fully Distributed Fiber Optic Strain Sensor Based on the Kerr Nonlinear Optical Effect, the Photoelastic Effect, and Counterpropagating Optical Pulses.

    NASA Astrophysics Data System (ADS)

    Kapteyn, Kelvin Lloyd

    1995-01-01

    Since the first fiber optic strain gage was described in 1978, a lot of research effort has been applied to the development of various fiber optic strain measurement schemes. Most of the approaches that have been studied so far measure the total strain from one end of the fiber to the other. Other approaches make "quasi-distributed" measurements based on measuring the change in length of several segments of the fiber. The eventual goal of these quasi-distributed systems is to reduce the segment length or the gage length until a continuous strain distribution could be measured. In this dissertation, a fully distributed fiber optic strain and temperature sensor is developed. This sensor is based on a strong Kerr effect in combination with a greatly increased photoelastic response and short, counterpropagating optical pulses. In combination with much shorter optical pulses, this approach promises great improvements in strain sensitivity and resolution. In addition, this system is capable of separating out strain components in both transverse directions of a polarization maintaining fiber as well as the axial strain component and the temperature at every point along the fiber. The measurement of three dimensional strain data and temperature in a fully distributed sensor is a very significant improvement over any previous system. The sensor should provide a very powerful tool for crack and flaw detection as well as other applications that need a strain distribution. Primary applications are expected to be nondestructive testing and health monitoring of composite structures by embedding the fiber sensor into the composite during manufacture. Such a sensor would be protected from environmental damage and would provide data on the internal integrity of the structure.

  13. Stability of pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Alexander, J. C.; Grillakis, M. G.; Jones, C. K. R. T.; Sandstede, B.

    Pulse stability is crucial to the effective propagation of information in a soliton-based optical communication system. It is shown in this paper that pulses in optical fibers, for which attenuation is compensated by phase-sensitive amplifiers, are stable over a large range of parameter values. A fourth-order nonlinear diffusion model due to Kutz and co-workers is used. The stability proof invokes a number of mathematical techniques, including the Evans function and Grillakis' functional analytic approach.

  14. The optical functions of silicon at elevated temperatures and their application to pulsed laser annealing

    SciTech Connect

    Jellison, G.E. Jr.; Lowndes, D.H.; Wood, R.F.

    1993-06-01

    The results of measurements of the optical functions of silicon at elevated temperatures are reviewed and the results applied to pulsed laser annealing of silicon. Several optical experiments which were performed to understand the physics of pulsed laser annealing are described, and related to detailed thermal modeling. The fabrication of silicon solar cells using both thermal and laser processing is described, both of which give very goods results.

  15. Optical pulse dynamics for quantum-dot logic operations in a photonic-crystal waveguide

    SciTech Connect

    Ma, Xun; John, Sajeev

    2011-11-15

    We numerically demonstrate all-optical logic operations with quantum dots (QDs) embedded in a bimodal photonic-crystal waveguide using Maxwell-Bloch equations in a slowly varying envelope approximation (SVEA). The two-level QD excitation level is controlled by one or more femtojoule optical driving pulses passing through the waveguide. Specific logic operations depend on the relative pulse strengths and their detunings from an inhomogeneouslly broadened (about 1% for QD transitions centered at 1.5 {mu}m) QD transition. This excitation controlled two-level medium then determines passage of subsequent probe optical pulses. Envelope equations for electromagnetic waves in the linear dispersion and cutoff waveguide modes are derived to simplify solution of the coupled Maxwell-Bloch equations in the waveguide. These determine the quantum mechanical evolution of the QD excitation and its polarization, driven by classical electromagnetic (EM) pulses near a sharp discontinuity in the EM density of states of the bimodal waveguide. Different configurations of the driving pulses lead to distinctive relations between driving pulse strength and probe pulse passage, representing all-optical logic and, or, and not operations. Simulation results demonstrate that such operations can be done on picosecond time scales and within a waveguide length of about 10 {mu}m in a photonic-band-gap (PBG) optical microchip.

  16. All-optical short pulse translation through cross-phase modulation in a VO₂ thin film.

    PubMed

    Fardad, Shima; Das, Susobhan; Salandrino, Alessandro; Breckenfeld, Eric; Kim, Heungsoo; Wu, Judy; Hui, Rongqing

    2016-01-15

    VO2 is a promising material for reconfigurable photonic devices due to the ultrafast changes in electronic and optical properties associated with its dielectric-to-metal phase transition. Based on a fiber-optic, pump-probe setup at 1550 nm wavelength window, and by varying the pump-pulse duration, we show that the material phase transition is primarily caused by the pump-pulse energy. For the first time, we demonstrate that the instantaneous optical phase modulation of probe during pump leading edge can be utilized to create short optical pulses at probe wavelength, through optical frequency discrimination. This circumvents the impact of long recovery time well known for the phase transition of VO2. PMID:26766683

  17. Transient magneto-optic effects in ferrofluid-filled microstructured fibers in pulsed magnetic field

    NASA Astrophysics Data System (ADS)

    Agruzov, Petr M.; Pleshakov, Ivan V.; Bibik, Efim E.; Stepanov, Serguei I.; Shamrai, Alexander V.

    2015-09-01

    Transient magneto-optic effects in ferrofluid-filled microstructured optical fibers are considered. Magneto-optic responses of two types, i.e., an even and an odd one, were observed in the longitudinal geometry of an applied pulsed magnetic field for the kerosene-based Fe3O4 ferrofluid with ∼8 \\text{nm} nanoparticles. For the first time a submicrosecond response time limited by the rise time of the applied field pulse (∼0.35 μ \\text{s}) was demonstrated for the odd magneto-optic effect in an all-fiber system, and responses of the even and odd magneto-optic effects were separated. A strong influence of the pulse width on the relaxation time of the even response is attributed to the formation of particle aggregates.

  18. Powerful 170-attosecond XUV pulses generated with few-cycle laser pulses and broadband multilayer optics

    NASA Astrophysics Data System (ADS)

    Schultze, M.; Goulielmakis, E.; Uiberacker, M.; Hofstetter, M.; Kim, J.; Kim, D.; Krausz, F.; Kleineberg, U.

    2007-07-01

    Single 170-as extreme ultraviolet (XUV) pulses delivering more than 106 photons/pulse at ~100 eV at a repetition rate of 3 kHz are produced by ionizing neon with waveform-controlled sub-5 fs near-infrared (NIR) laser pulses and spectrally filtering the emerging near-cutoff high-harmonic continuum with a broadband, chirped multilayer molybdenum silicon (Mo/Si) mirror.

  19. Comparison of ultrashort-pulse frequency-resolved-optical-gating traces for three common beam geometries

    SciTech Connect

    DeLong, K.W.; Trebino, R. ); Kane, D.J. )

    1994-09-01

    We recently introduced frequency-resolved optical gating (FROG), a technique for measuring the intensity and phase of an individual, arbitrary, ultrashort laser pulse. FROG can use almost any instantaneous optical nonlinearity, with the most common geometries being polarization gate, self-diffraction, and second-harmonic generation. The experimentally generated FROG trace is intuitive, visually appealing, and can yield quantitative information about the pulse parameters (such as temporal and spectral width and chirp). However, the qualitative and the quantitative features of the FROG trace depend strongly on the geometry used. We compare the FROG traces for several common ultrashort pulses for these three common geometries and, where possible, develop scaling rules that allow one to obtain quantitative information about the pulse directly from the experimental FROG trace. We illuminate the important features of the various FROG traces for transform-limited, linearly chirped, self-phase modulated, and nonlinearly chirped pulses, pulses with simultaneous linear chirp and self-phase modulation, and pulses with simultaneous linear chirp and cubic phase distortion, as well as double pulses, pulses with phase jumps, and pulses with complex intensity and phase substructure.

  20. Kilohertz generation of high contrast polarization states for visible femtosecond pulses via phase-locked acousto-optic pulse shapers

    SciTech Connect

    Seiler, Hélène; Walsh, Brenna; Palato, Samuel; Kambhampati, Patanjali; Thai, Alexandre; Forget, Nicolas; Crozatier, Vincent

    2015-09-14

    We present a detailed analysis of a setup capable of arbitrary amplitude, phase, and polarization shaping of broadband visible femtosecond pulses at 1 kHz via a pair of actively phase stabilized acousto-optic programmable dispersive filters arranged in a Mach-Zehnder interferometer geometry. The setup features phase stability values around λ/225 at 580 nm as well as degrees of polarization of at least 0.9 for any polarization state. Both numbers are important metrics to evaluate a setup's potential for applications based on polarization-shaped femtosecond pulses, such as fully coherent multi-dimensional electronic spectroscopy.

  1. Information coding of exciting laser pulses in an optical echo-processor

    SciTech Connect

    Rusanova, I A

    2013-07-31

    We report the possibility of controlling the distribution of quantum bits within an inhomogeneously broadened line of a resonant transition in recording and transforming information in optical echo-processors. We consider the efficiency of realisation of the elementary logic XOR gate based on a two-pulse excitation of a resonant medium with phase memory. The encoded information is incorporated into the temporal shape of laser pulses in the form of amplitude modulation of an 'echelon' of present ('1') and absent ('0') pulse-codes for obtaining more efficient logic elements that reduce the noise in a quantum communication channel. (optical information processing)

  2. Blind frequency-resolved optical-gating pulse characterization for quantitative differential multiphoton microscopy.

    PubMed

    Field, Jeffrey J; Durfee, Charles G; Squier, Jeff A

    2010-10-15

    We use a unique multifocal multiphoton microscope to directly characterize the pulse in the focal plane of a high-NA objective using second-harmonic generation frequency-resolved optical gating (FROG). Because of the nature of the optical setup, femtosecond laser pulses of orthogonal polarization states are generated in the focal plane, each acquiring a different spectral dispersion. By applying an additional constraint on the phase extraction algorithm, we simultaneously extract both the gate and probe pulses from a single spectrogram with a FROG error of 0.016. PMID:20967069

  3. 1  MW peak-power subpicosecond optical pulse source based on a gain-switched laser diode.

    PubMed

    Fang, Yi-Cheng; Chaki, Tomohiro; Hung, Jui-Hung; Yamada, Hirohito; Yokoyama, Hiroyuki

    2016-09-01

    We have generated optical pulses of 1.2 MW peak power and 0.6 ps duration using a 1060 nm band gain-switched laser diode pulse oscillator. Optical pulses are amplified by three-stage ytterbium-doped fiber amplifiers, and remarkable reductions of amplified spontaneous emission noise and temporal duration have been accomplished based on self-phase modulation in the middle-stage amplifier. After the main amplifier, optical pulses were temporally compressed by a grating pair, and this enabled generation of subpicosecond optical pulses with over 1 MW peak power. PMID:27607964

  4. Generation of optical frequency combs in fibres: an optical pulse analysis

    NASA Astrophysics Data System (ADS)

    Zajnulina, Marina; Böhm, Michael; Blow, Keith; Chavez Boggio, José M.; Rieznik, Andres A.; Haynes, Roger; Roth, Martin M.

    2014-07-01

    The innovation of optical frequency combs (OFCs) generated in passive mode-locked lasers has provided astronomy with unprecedented accuracy for wavelength calibration in high-resolution spectroscopy in research areas such as the discovery of exoplanets or the measurement of fundamental constants. The unique properties of OCFs, namely a highly dense spectrum of uniformly spaced emission lines of nearly equal intensity over the nominal wavelength range, is not only beneficial for high-resolution spectroscopy. Also in the low- to medium-resolution domain, the OFCs hold the promise to revolutionise the calibration techniques. Here, we present a novel method for generation of OFCs. As opposed to the mode-locked laser-based approach that can be complex, costly, and difficult to stabilise, we propose an all optical fibre-based system that is simple, compact, stable, and low-cost. Our system consists of three optical fibres where the first one is a conventional single-mode fibre, the second one is an erbium-doped fibre and the third one is a highly nonlinear low-dispersion fibre. The system is pumped by two equally intense continuous-wave (CW) lasers. To be able to control the quality and the bandwidth of the OFCs, it is crucial to understand how optical solitons arise out of the initial modulated CW field in the first fibre. Here, we numerically investigate the pulse evolution in the first fibre using the technique of the solitons radiation beat analysis. Having applied this technique, we realised that formation of higherorder solitons is supported in the low-energy region, whereas, in the high-energy region, Kuznetsov-Ma solitons appear.

  5. Isolated-attosecond-pulse generation with infrared double optical gating

    SciTech Connect

    Lan Pengfei; Takahashi, Eiji J.; Midorikawa, Katsumi

    2011-06-15

    We propose and theoretically demonstrate an infrared two-color polarization gating scheme for generating an intense isolated attosecond pulse (IAP) in the multicycle regime. Our simulations show that an IAP can be produced using a multicycle two-color driving pulse with a duration up to 60 fs. Moreover, the carrier-envelope phase (CEP) of the driving laser is not required to be stabilized, although the IAP intensity changes with the CEP slip. Such a gating scheme significantly relaxes the requirements for driving lasers and opens the door to easily create intense IAPs with a high-power conventional multicycle laser pulse.

  6. Time and wavelength interleaved pulse trains generation based on pure phase processing of optical spectral comb

    NASA Astrophysics Data System (ADS)

    Gao, Hongbiao; Chen, Minghua; Chen, Hongwei; Xie, Shizhong

    2014-02-01

    By applying linear phase to optical spectral comb, we experimentally demonstrate that the time interval of the compressed pulse trains with different wavelength can be precisely controlled for the generation of time and wavelength interleaved pulse train. The time and wavelength interleaved pulse train with the repetition rate of 40 GHz and 80 GHz are generated based on this and the possibility to improve the performance of the generated pulse train is also discussed. We also measure the precision of time delay obtained by applying linear phase to the comb.

  7. Integrated operations of the National Ignition Facility (NIF) optical pulse generation development system

    SciTech Connect

    Browning, D.; Crane, J. K.; Dane, C. B.; Hackel; Henesian, M.; Hopps, N. W.; Martinez, M. D.; Moran, B.; Penko, F.; Rothenberg, J. E.; Wilcox, R. B.

    1998-07-31

    We describe the Optical Pulse Generation (OPG) testbed, which is the integration of the MOR and Preamplifier Development Laboratories. We use this OPG testbed to develop and demonstrate the overall capabilites of the NIF laser system front end. We will present the measured energy and power output, temporal and spatial pulse shaping capability, FM bandwidth and dispersion for beam smoothing, and measurements of the pulse-to-pulse power variation of the OPG system and compare these results with the required system performance specifications. We will discuss the models that are used to predict the system performance and how the OPG output requirements flowdown to the subordinate subsystems within the OPG system.

  8. Peculiarities of the propagation of multidimensional extremely short optical pulses in germanene

    NASA Astrophysics Data System (ADS)

    Zhukov, Alexander V.; Bouffanais, Roland; Konobeeva, Natalia N.; Belonenko, Mikhail B.

    2016-09-01

    In this Letter, we study the propagation characteristics of both two-dimensional and three-dimensional extremely short optical pulses in germanene. A distinguishing feature of germanene-in comparison with other graphene-like structures-is the presence of a significant spin-orbit interaction. The account of this interaction has a significant impact on the evolution of extremely short pulses in such systems. Specifically, extremely short optical pulses, consisting of two electric field oscillations, cause the appearance of a tail associated with the excitation of nonlinear waves. Due to the large spin-orbit interaction in germanene, this tail behind the main pulse is much smaller in germanene-based samples as compared to graphene-based ones, thereby making germanene a preferred material for the stable propagation of pulses along the sample.

  9. Analytical description of 3D optical pulse diffraction by a phase-shifted Bragg grating.

    PubMed

    Golovastikov, Nikita V; Bykov, Dmitry A; Doskolovich, Leonid L; Soifer, Victor A

    2016-08-22

    Diffraction of a three-dimensional (3D) spatiotemporal optical pulse by a phase-shifted Bragg grating (PSBG) is considered. The pulse diffraction is described in terms of signal transmission through a linear system with a transfer function determined by the reflection or transmission coefficient of the PSBG. Resonant approximations of the reflection and transmission coefficients of the PSBG as functions of the angular frequency and the in-plane component of the wave vector are obtained. Using these approximations, a hyperbolic partial differential equation (Klein-Gordon equation) describing a general class of transformations of the incident 3D pulse envelope is derived. A solution to this equation is found in the form of a convolution integral. The presented rigorous simulation results fully confirm the proposed theoretical description. The obtained results may find application in the design of new devices for spatiotemporal pulse shaping and for optical information processing and analog optical computing. PMID:27557167

  10. Excitability and optical pulse generation in semiconductor lasers driven by resonant tunneling diode photo-detectors.

    PubMed

    Romeira, Bruno; Javaloyes, Julien; Ironside, Charles N; Figueiredo, José M L; Balle, Salvador; Piro, Oreste

    2013-09-01

    We demonstrate, experimentally and theoretically, excitable nanosecond optical pulses in optoelectronic integrated circuits operating at telecommunication wavelengths (1550 nm) comprising a nanoscale double barrier quantum well resonant tunneling diode (RTD) photo-detector driving a laser diode (LD). When perturbed either electrically or optically by an input signal above a certain threshold, the optoelectronic circuit generates short electrical and optical excitable pulses mimicking the spiking behavior of biological neurons. Interestingly, the asymmetric nonlinear characteristic of the RTD-LD allows for two different regimes where one obtain either single pulses or a burst of multiple pulses. The high-speed excitable response capabilities are promising for neurally inspired information applications in photonics. PMID:24103966

  11. Laser pulse amplitude changes induced by terahertz waves under linear electro-optic effect

    SciTech Connect

    Ilyakov, I. E. Shishkin, B. V.; Kitaeva, G. Kh.; Akhmedzhanov, R. A.

    2014-04-14

    Changes in the amplitude of femtosecond laser pulses and in the energy of terahertz wave radiation induced during their co-propagation in ZnTe and GaP crystals are studied theoretically and experimentally. The results show that variation of the optical field amplitude leads to changes in the laser pulse energy and spectrum shift. We investigate the quantitative correlations between variations of the optical pulse energy, spectrum, phase and terahertz radiation energy. The values of laser pulse energy change and spectrum shift are proportional to the first time derivative of the magnitude of terahertz electric field, which enables coherent electro-optic detection. A simple and convenient calibration technique for terahertz energy detectors based on the correlation between laser and terahertz energy changes is proposed and tested.

  12. Phase-sensitive optical coherence reflectometer with differential phase-shift keying of probe pulses

    SciTech Connect

    Alekseev, A E; Vdovenko, V S; Sergachev, I A; Simikin, D E; Gorshkov, B G; Potapov, V T

    2014-10-31

    We report a new method for reconstructing the signal shape of the external dynamic perturbations along the entire length of the fibre of an optical coherence reflectometer. The method proposed is based on differential phase-shift keying of a probe pulse and demodulation of scattered light by the phase diversity technique. Possibilities of the method are demonstrated experimentally. (fibre-optic sensors)

  13. Optical guiding of terawatt laser pulses in the plasma waveguide

    NASA Astrophysics Data System (ADS)

    Alexeev, I.; Fan, J.; Kim, K. Y.; Nikitin, S.; Milchberg, H. M.

    1999-11-01

    We report coupling and guiding of pulses of peak power 0.5 TW in 1.5 cm long preformed plasma waveguides generated in a high repetition rate argon gas jet. Greater than 50 percent coupling was measured in the injection of 50 mJ, 100 fs pulses, giving guided intensities up to 10^17 W/cm^2. For short delays between waveguide generation and pulse injection, refraction-induced pulse shortening occurred, with this effect reduced either by increasing the delay between waveguide generation and injection or by injecting a prepulse into the waveguide. We will also describe recent experiments which attempt to reduce the avalanche ionization threshold for the gases in which the waveguide is generated. This work is supported by the US Department of Energy (DEF G0297 ER 41039) and the National Science Foundation (PHY-9515509).

  14. Generation of tunable few optical-cycle pulses by visible-to-infrared frequency conversion

    NASA Astrophysics Data System (ADS)

    Darginavičius, J.; Tamošauskas, G.; Piskarskas, A.; Valiulis, G.; Dubietis, A.

    2012-07-01

    We demonstrate a simple method for infrared few optical-cycle pulse generation, which is based on collinear visible-to-infrared frequency conversion and involves difference-frequency generation and subsequent two-step optical parametric amplification. The numerical simulations and experiments using BBO crystals show an efficient frequency down conversion of visible ˜20 fs pulses from a commercial blue-pumped noncollinear optical parametric amplifier yielding 1.2-2.4 μm tunable sub-100 μJ pulses with duration of 3 to 5 optical-cycles. The proposed method could be readily extended to generate few optical-cycle pulses in the mid-infrared spectral range (up to 5.5 μm) using, e.g., LiIO3 and LiNbO3 crystals, as demonstrated by the numerical simulations. In these crystals, even shorter, two-optical-cycle mid-infrared pulses could be obtained at particular wavelengths where group velocity matching between the signal and idler waves is achieved.

  15. Precision spectral manipulation of optical pulses using a coherent photon echo memory.

    PubMed

    Buchler, B C; Hosseini, M; Hétet, G; Sparkes, B M; Lam, P K

    2010-04-01

    Photon echo schemes are excellent candidates for high efficiency coherent optical memory. They are capable of high-bandwidth multipulse storage, pulse resequencing and have been shown theoretically to be compatible with quantum information applications. One particular photon echo scheme is the gradient echo memory (GEM). In this system, an atomic frequency gradient is induced in the direction of light propagation leading to a Fourier decomposition of the optical spectrum along the length of the storage medium. This Fourier encoding allows precision spectral manipulation of the stored light. In this Letter, we show frequency shifting, spectral compression, spectral splitting, and fine dispersion control of optical pulses using GEM. PMID:20364227

  16. Dynamic response of the human retina to pulsed optical and electrical stimulation

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Bakutkin, Valery V.; Kamenskih, Tatyana G.; Zemskova, Tatyana M.; Ahuja, Poonam

    2000-04-01

    Transcutaneous millisecond stimulation of the retina by electric pulses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.

  17. Frequency-resolved optical-gating measurements of ultrashort pulses using surface third-harmonic generation

    SciTech Connect

    Tsang, T.; Krumbuegel, M.A.; DeLong, K.W.; Fittinghoff, D.N.; Trebino, R.

    1996-09-01

    We demonstrate what is to our knowledge the first frequency-resolved optical gating (FROG) technique to measure ultrashort pulses from an unamplified Ti:sapphire laser oscillator without direction-of-time ambiguity. This technique utilizes surface third-harmonic generation as the nonlinear-optical effect and, surprisingly, is the most sensitive third-order FROG geometry yet. {copyright} {ital 1996 Optical Society of America.}

  18. Effects of Birefringence and Nonlinearity on Optical Pulse Propagation in New Types of Optical Fibers

    SciTech Connect

    Curtis R. Menyuk; Gary M. Carter

    2005-05-15

    The purpose of this grant was to allow us to complete work that we had already begun on spun optical fibers and to begin studies of holey and photonic crystal optical fibers. The work on spun optical fibers was completed with great success. It led to several publications in collaboration with our co-workers at the Universita di Padova, and the student who carried out this work received a major award from the Universita di Padova. The work on holey and photonic crystal fibers has proceeded more slowly, but, in collaboration with Korean co-workers at the Gwangju Institute of Science and Technology, we have developed three different computational models that allow us to calculate the modes of these fibers: a Galerkin model, a plane wave model, and a multipole model. We have applied these models to the study of mode coupling in periodic gratings. In collaboration with scientists at the Naval Research Laboratory, we have also applied these models to the study of pulse compression in tapered fibers and the development of nonlinear fibers that are capable of handling large powers in high-index and chalcogenide glasses. European and Asian countries have made large investments in the development of these new glass technologies, while the United States has not. As a consequence, the United States is falling behind in what we believe will prove to be a critical area of nanotechnology. It is our view that by investing in this project, the Department of Energy has helped lay the groundwork for future development of special fiber technology in the United States, once the decision has been made that the United States cannot continue to stand on the sidelines as this technology--which appears to have great commercial and military value--is developed elsewhere.

  19. LASER PLASMA: Experimental confirmation of the erosion origin of pulsed low-threshold surface optical breakdown of air

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ya; Chumakou, A. N.; Chivel', Yu A.

    1988-08-01

    Nanosecond kinetic spectroscopy techniques were used to identify the erosion origin of pulsed low-threshold surface optical breakdown of air as a result of interaction of microsecond neodymium and CO2 laser pulses with some metals (indium, lead).

  20. Coherent Combining of Optical Pulses in Spatial, Spectral and Time Domains

    NASA Astrophysics Data System (ADS)

    Zhou, Tong

    Petawatt-level laser pulses have many potential applications in science and industry, but will require three orders of magnitude increase in pulse repetition rate from existing solid-state laser technology. Fiber lasers can operate at such repetition rates, but are limited in pulse energy. To overcome the gap between current achievable fiber-laser pulse energies (˜mJ) and required pulse energies for high-energy applications (up to 10J), this dissertation work explores four novel techniques: (1) Coherent beam combining in the spatial domain; (2) Coherent spectral combining in spatial and spectral domains; (3) Coherent pulse stacking amplification in the time domain; (4) N-squared coherent combining in spatial and time domains. (1) We demonstrate coherent femtosecond pulse beam combining of up to four chirped-pulse fiber amplifier channels. Theoretical and experimental analysis of combining efficiency dependence on amplitude/phase noise shows the scalability to a large number of channels. (2) We demonstrate coherent femtosecond pulse spectral synthesis by combining three parallel fiber chirped-pulse amplifiers, each amplifying different pulse spectra. This technique simultaneously overcomes individual-amplifier energy/power limitations, and spectral gain narrowing in a single fiber amplifier. (3) We propose and demonstrate a new technique of coherent pulse stacking (CPS) amplification, which uses reflecting resonators to transform a sequence of phase/amplitude modulated optical pulses into a single output pulse. Experimental validation with a single resonator is demonstrated. We show theoretically that the extension to stacking a large number of equal-amplitude pulses can be achieved using multiple reflecting resonators, which enables the extraction of all stored energy in large-core fiber amplifiers. (4) We propose and demonstrate N-squared coherent combining using resonant optical cavities, a novel pulse combining technique based on both spatial combining and

  1. Fiber-Optic Distribution Of Pulsed Power To Multiple Sensors

    NASA Technical Reports Server (NTRS)

    Kirkham, Harold

    1996-01-01

    Optoelectronic systems designed according to time-sharing scheme distribute optical power to multiple integrated-circuit-based sensors in fiber-optic networks. Networks combine flexibility of electronic sensing circuits with advantage of electrical isolation afforded by use of optical fibers instead of electrical conductors to transmit both signals and power. Fiber optics resist corrosion and immune to electromagnetic interference. Sensor networks of this type useful in variety of applications; for example, in monitoring strains in aircraft, buildings, and bridges, and in monitoring and controlling shapes of flexible structures.

  2. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire

    PubMed Central

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-01-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication. PMID:27609521

  3. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire.

    PubMed

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-01-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication. PMID:27609521

  4. Measuring ultrashort pulses using frequency-resolved optical gating

    SciTech Connect

    Trebino, R.

    1993-12-01

    The purpose of this program is the development of techniques for the measurement of ultrafast events important in gas-phase combustion chemistry. Specifically, goals of this program include the development of fundamental concepts and spectroscopic techniques that will augment the information currently available with ultrafast laser techniques. Of equal importance is the development of technology for ultrafast spectroscopy. For example, methods for the production and measurement of ultrashort pulses at wavelengths important for these studies is an important goal. Because the specific vibrational motion excited in a molecule depends sensitively on the intensity, I(t), and the phase, {psi}(t), of the ultrashort pulse used to excite the motion, it is critical to measure both of these quantities for an individual pulse. Unfortunately, this has remained an unsolved problem for many years. Fortunately, this year, the authors present a technique that achieves this goal.

  5. Control of ionization and dissociation by optical pulse trains.

    PubMed

    Kirrander, A; Jungen, Ch; Fielding, H H

    2010-08-21

    Ever since the first lasers were built over 40 years ago, chemists and physicists have been attempting to exploit them as tools for controlling the outcome of chemical reactions. Over the last decade this dream has become a reality. The most successful approaches have employed learning algorithms to shape femtosecond laser pulses; however, in these experiments, the laser light effectively learns for itself what pulse shape is required to generate a specific product and it is not always easy to unravel the underlying physics of the control process. In this theoretical investigation we unravel the mechanism of ionisation/dissociation control in the prototypical H(2) molecule. We track the excited state molecular dynamics from the moment of interaction with the laser field to ionization and dissociation, and determine how sequences of carefully tuned laser pulses are able to change the ionization/dissociation branching ratio. PMID:20532353

  6. Generation of carrier-envelope phase-stable mid-infrared pulses via dual-wavelength optical parametric amplification.

    PubMed

    Kaneshima, Keisuke; Ishii, Nobuhisa; Takeuchi, Kengo; Itatani, Jiro

    2016-04-18

    Carrier-envelope phase-stable mid-infrared pulses spanning from 5 μm to 11 μm with a pulse energy of 5 μJ were produced by difference frequency generation of two-color near-infrared pulses that were produced in a novel inline optical parametric amplifier. The mid-infrared electric waveform was characterized by electro-optic sampling using 6.5-fs pulses at 620 nm. PMID:27137301

  7. Optical generation of intense ultrashort magnetic pulses at the nanoscale

    NASA Astrophysics Data System (ADS)

    Tsiatmas, Anagnostis; Atmatzakis, Evangelos; Papasimakis, Nikitas; Fedotov, Vassili; Luk'yanchuk, Boris; Zheludev, Nikolay I.; García de Abajo, F. Javier

    2013-11-01

    Generating, controlling and sensing strong magnetic fields at ever shorter time and length scales is important for both fundamental solid-state physics and technological applications such as magnetic data recording. Here, we propose a scheme for producing strong ultrashort magnetic pulses localized at the nanoscale. We show that a bimetallic nanoring illuminated by femtosecond laser pulses responds with transient thermoelectric currents of picosecond duration, which in turn induce Tesla-scale magnetic fields in the ring cavity. Our method provides a practical way of generating intense nanoscale magnetic fields with great potential for materials characterization, terahertz radiation generation and data storage applications.

  8. Characterization of arbitrary femtosecond pulses using frequency-resolved optical gating

    SciTech Connect

    Kane, D.J. ); Trebino, R. )

    1993-02-01

    The authors introduce a new technique, which they call frequency-resolved optical gating (FROG), for characterizing and displaying arbitrary femtosecond pulses. The method is simple, general, broad-band, and does not require a reference pulse. Using virtually any instantaneous nonlinear-optical effect, FROG involves measuring the spectrum of the signal pulse as a function of the delay between two input pulses. The resulting trace of intensity versus frequency and delay is related to the pulse's spectrogram, a visually intuitive transform containing both time and frequency information. They prove, using phase retrieval concepts, that the FROG trace yields the full intensity l(t) and phase [var phi](t) of an arbitrary ultrashort pulse with no physically significant ambiguities. They argue, in analogy with acoustics problems, that the FROG trace is in many ways as useful a representation of the pulse as the field itself. FROG appears to have temporal resolution limited only by the response of the nonlinear medium. They demonstrate the method using self-diffraction via the electronic Kerr effect in BK-7 glass and few [mu]J, 620 nm, linearly chirped, [approximately]200 fs pulses.

  9. Effect of laser pulse repetition frequency on the optical breakdown threshold of quartz glass

    SciTech Connect

    Kononenko, T V; Konov, V I; Schöneseiffen, S; Dausinger, F

    2013-08-31

    The thresholds of optical breakdown in the volume of quartz glass were measured in relation to the number of pulses under irradiation by ultrashort laser pulses with different pulse repetition frequencies (1 – 400 kHz). Increasing this frequency from 10 to 400 kHz was found to substantially lower the breakdown threshold for 500-fs long pulses (at a wavelength of 1030 nm) and to lower to a smaller degree for 5-ps long pulses (515 nm). A strong frequency dependence of the breakdown threshold is observed under the same conditions as a manifold decrease of the breakdown threshold with increase in the number of pulses in a pulse train. The dependence of the optical breakdown on the number of pulses is attributable to the accumulation of point defects under multiple subthreshold irradiation, which affects the mechanism of collisional ionisation. In this case, the frequency dependence of the breakdown threshold of quartz glass is determined by the engagement of shortlived defects in the ionisation mechanism. (interaction of laser radiation with matter)

  10. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    SciTech Connect

    Sajadi, Mohsen Wolf, Martin; Kampfrath, Tobias

    2014-03-03

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ∼1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  11. Monitoring of railway embankment settlement with fiber-optic pulsed time-of-flight radar

    NASA Astrophysics Data System (ADS)

    Kilpelä, Ari; Lyöri, Veijo; Duan, Guoyong

    2012-12-01

    This paper deals with a fiber-optic pulsed time-of-flight (PTOF) laser radar used for monitoring the settlement of a railway embankment. The operating principle is based on evaluating the changes in the lengths of the fiber-optic cables embedded in the embankment by measuring the time separation of the optical pulses reflected from both ends of the sensor fiber. The advantage of this method is that it integrates the elongation of the whole sensor, and many sensor fibers can be connected in series. In a field test, seven polyurethane-coated optical cables were installed in a railway embankment and used as 20-m long sensors. The optical timing pulses were created using specially polished optical connectors. The measured precision was 0.28 ps, which corresponds 1.8 μstrain elongation using a 20 m long sensor fiber, using an averaged value of 10 000 pulses for a single measurement value. The averaged elongation value of all sensors was used for cancelling out the effect of temperature variation on the elongation value of each individual sensor. The functionality of the method was tested by digging away a 7.5 m long and approximately 18 mm high section of sand below one sensor. It was measured as a +3 mm change in the length of the sensor fiber, which matched well with the theoretically calculated elongation value, 2.9 mm. The sensor type proved to be strong but flexible enough for this type of use.

  12. A broadly tunable autocorrelator for ultra-short, ultra-high power infrared optical pulses

    SciTech Connect

    Szarmes, E.B.; Madey, J.M.J.

    1995-12-31

    We describe the design of a crossed-beam, optical autocorrelator that uses an uncoated, birefringent beamsplitter to split a linearly polarized incident pulse into two orthogonally polarized pulses, and a Type II, SHG crystal to generate the intensity autocorrelation function. The uncoated beamsplitter accommodates extremely broad tunability while precluding any temporal distortion of ultrashort optical pulses at the dielectric interface, and the specific design provides efficient operation between 1 {mu}m and 4 {mu}m. Furthermore, the use of Type II SHG completely eliminates any single-beam doubling, so the autocorrelator can be operated at very shallow crossed-beam angles without generating a background pedestal. The autocorrelator has been constructed and installed in the Mark III laboratory at Duke University as a broadband diagnostic for ongoing compression experiments on the chirped-pulse FEL.

  13. Fluctuations of energy density of short-pulse optical radiation in the turbulent atmosphere.

    PubMed

    Banakh, V A; Smalikho, I N

    2014-09-22

    Fluctuations of energy density of short-pulse optical radiation in the turbulent atmosphere have been studied based on numerical solution of the parabolic wave equation for the complex spectral amplitude of the wave field by the split-step method. It has been shown that under conditions of strong optical turbulence, the relative variance of energy density fluctuations of pulsed radiation of femtosecond duration becomes much less than the relative variance of intensity fluctuations of continuous-wave radiation. The spatial structure of fluctuations of the energy density with a decrease of the pulse duration becomes more large-scale and homogeneous. For shorter pulses the maximal value of the probability density distribution of energy density fluctuations tends to the mean value of the energy density. PMID:25321700

  14. Generation of ultra-short THz pulses in new optical nonlinear materials based on organic polymers

    NASA Astrophysics Data System (ADS)

    Mikerin, S. L.; Plekhanov, A. I.; Simanchuk, A. V.; Yakimanskii, A. V.

    2016-07-01

    Using the method of optical rectification of femtosecond laser pulses, we report the generation of short (a few field cycles) terahertz pulses in the samples of films based on polyimides with covalently bound chromophore molecules of DR type. The spectral width of the produced pulses is limited by the pump pulse duration. The quadratic nonlinear optical properties are imparted to the films in the process of their fabrication by orienting the chromophore molecules in the external electric field of the applied electrodes having an original configuration. The samples are compared with the ZnTe crystal. Using the methods of coherent spectroscopy, their transmission and refractive index dispersion spectra are investigated in the frequency range 0.5 – 2.6 THz. The studied polymer composition is promising for the application in coherent spectrometers both for increasing the working spectral range without dips and for improving the spatial resolution in the near-field terahertz spectroscopy.

  15. Short optical pulse generation at 40 GHz with a bulk electro-absorption modulator packaged device

    NASA Astrophysics Data System (ADS)

    Langlois, Patrick; Moore, Ronald; Prosyk, Kelvin; O'Keefe, Sean; Oosterom, Jill A.; Betty, Ian; Foster, Robert; Greenspan, Jonathan; Singh, Priti

    2003-12-01

    Short optical pulse generation at 40GHz and 1540nm wavelength is achieved using fully packaged bulk quaternary electro-absorption modulator modules. Experimental results obtained with broadband and narrowband optimized packaged modules are presented and compared against empirical model predictions. Pulse duty cycle, extinction ratio and chirp are studied as a function of sinusoidal drive voltage and detuning between operating wavelength and modulator absorption band edge. Design rules and performance trade-offs are discussed. Low-chirp pulses with a FWHM of ~12ps and sub-4ps at a rate of 40GHz are demonstrated. Optical time-domain demultiplexing of a 40GHz to a 10GHz pulse train is also demonstrated with better than 20dB extinction ratio.

  16. Direct space-to-time pulse shaping for ultrafast optical waveform generation

    NASA Astrophysics Data System (ADS)

    Leaird, Daniel E.

    The high-speed photonic network industry, driven by the demands of enormous growth of network data traffic, has grown to be a multi-billion dollar entity. The availability of increased data traffic has come about due to the growth in bandwidth transmitted over optical fiber. This growth is primarily due to research in two areas-time-division-multiplexed (TDM), and wavelength-division-multiplexed (WDM) photonic network schemes. A key bottleneck in these high-speed photonic networks is the optical-electronic (OE) interface. Currently, multiple laser sources and/or multiple serial optoelectronic modulators are used to implement the OE interface in both photonic network schemes. In this thesis, an apparatus will be demonstrated that could act as a relatively simple OE interface for these high-speed photonic networks. The optical system, a direct space-to-time (DST) pulse shaper, converts a 1-D spatially patterned short optical pulse directly into a serial ultrafast time-domain waveform in a configuration compatible with the use of high-speed reflection modulator arrays. The space-to-time conversion properties, chirp compensation/cancellation, and potential for multiple spatially separated but wavelength shifted outputs will be examined theoretically and experimentally. Integrated optic implementations of the DST pulse shaper, based on a common high-speed WDM network component, will be investigated as well. Work on the bulk optics implementation of the DST shaper provides considerable insight into the operation of the integrated optics implementations. The space-to-time mapping, and multiple output channel characteristics of the bulk optics DST are shown to function similarly in the integrated optics implementations. These integrated optic versions of the DST pulse shaper may play a significant role in future high-speed photonic networks.

  17. Estimating of pulsed electric fields using optical measurements.

    SciTech Connect

    Flanagan, Timothy McGuire; Chantler, Gary R.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  18. Nonlinear dynamics of optical pulses in fibres with a travelling refractive-index-change wave

    SciTech Connect

    Adamova, M S; Zolotovskii, Igor' O; Sementsov, Dmitrii I

    2009-03-31

    Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear. (solitons)

  19. Observation of self-focusing in optical fibers with picosecond pulses.

    PubMed

    Baldeck, P L; Raccah, F; Alfano, R R

    1987-08-01

    Self-focusing was observed at Raman frequencies, using picosecond pulses propagating in a large-core optical fiber of 100-microm diameter. For intense input pulses, a continuum of Stokes frequencies was generated in a small ring-waveguide structure. The ring diameter of 11 microm was about 10 times smaller than the beam diameter at low intensities. The ring structure was attributed to an induced-gradient-index profile arising from the nonlinear index of refraction. PMID:19741807

  20. SOLITONS: Nonlinear dynamics of optical pulses in fibres with a travelling refractive-index-change wave

    NASA Astrophysics Data System (ADS)

    Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

    2009-03-01

    Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear.

  1. Two and Three Beam Pumped Optical Parametric Amplifier of Chirped Pulses

    NASA Astrophysics Data System (ADS)

    Ališauskas, S.; Butkus, R.; Pyragaitė, V.; Smilgevičius, V.; Stabinis, A.; Piskarskas, A.

    2010-04-01

    We present two and three beam pumped optical parametric amplifier of broadband chirped pulses. The seed pulses from Ti:sapphire oscillator were stretched and amplified in a non-collinear geometry pumping with up to three beams derived from independent laser amplifiers. The signal with ˜90 nm bandwidth was amplified up to 0.72 mJ. The conversion efficiency dependence on intersection angles of pump beams is also revealed.

  2. Role of the optical pulse repetition rate in the efficiency of terahertz emitters

    NASA Astrophysics Data System (ADS)

    Reklaitis, Antanas

    2016-07-01

    Excitation of n-GaAs and p-InAs terahertz emitters by the series of optical pulses is studied by ensemble Monte Carlo simulations. It is found that the spatial separation of photoexcited electrons and holes dramatically reduces the recombination intensity in n-GaAs emitter, the operation of which is based on the surface field effect. The spatial separation of carriers does not affect the recombination intensity in p-InAs emitter, the operation of which is based on the photo-Dember effect. Therefore, the recovery time of equilibrium state after optical pulse in n-GaAs emitter significantly exceeds the corresponding recovery time in p-InAs emitter. This fact leads to a substantial reduction of photocurrent amplitude in n-GaAs emitter excited by the optical pulse series at high repetition rate.

  3. Observation of voids and optical seizing of voids in silica glass with infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Watanabe, Wataru; Toma, Tadamasa; Yamada, Kazuhiro; Nishii, Junji; Hayashi, Ken-ichi; Itoh, Kazuyoshi

    2000-11-01

    Many researchers have investigated the interaction of femtosecond laser pulses with a wide variety of materials. The structural modifications both on the surface and inside the bulk of transparent materials have been demonstrated. When femtosecond laser pulses are focused into glasses with a high numerical-aperture objective, voids are formed. We demonstrate that one can seize and move voids formed by femtosecond laser pulses inside silica glass and also merge two voids into one. We also present clear evidence that a void is a cavity by showing a scanning-electron-microscope image of cleft voids: we clove through the glass along a plane that includes the laser-ablated thin line on the surface and the voids formed inside. The optical seizing and merging of voids are important basic techniques for fabricate micro-optical dynamic devices, such as the rewritable 3-D optical storage.

  4. Dynamic response of ensemble neurons to pulsed optical and electrical excitation in vivo and in vitro

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Seleverstov, George A.; Kamenskih, Tatyana G.; Akchurin, George G.; Bondarenko, Olga A.

    2002-07-01

    The nonlinear response of the Hodgkin-Huxley model neuron with external electrical pulsed was investigated. Dynamic response of somatic frog nerve on electrical pulsed duration was study in vitro. Transcutaneous millisecond of excitation of the ganglion cell of the human retina by electric uses is used for diagnosis, determination of the extent of optic nerve damage, and also partial restoration of visual function in patients with glaucoma, myopia and different types of optic nerve atrophy. Correlation between the threshold of phosphen formation and duration of the stimulating electric pulses was determined experimentally in normal eyes and in eyes with various pathologies. Comparison of optical and electrical scintillating frequency gives information about the dynamic processes in the normal and pathological retina.

  5. Pulse propagation and optical-klystron free-electron-laser devices.

    PubMed

    Dattoli, G; Mezi, L; Bucci, L

    2000-06-01

    We derive the equation governing the evolution of the optical field amplitude of a free-electron-laser oscillator operating in the optical-klystron configuration. The equation includes short pulse effects, due to the finite length of the electron bunches, and are valid under the assumption of small signal regime and low gain. Stationary solutions of the supermode type, analogous to those of conventional free-electron-laser configurations, are shown to exist for this case, too. Analytical expressions for the optical pulse shape are derived, without any assumption of dominance of the dispersive section, in the case of the long bunch regime, namely when the bunch length is larger than the slippage length. We present useful gain formulas, including the combined effect of dispersive section and pulse effects, and discuss the limits of validity of our treatment. PMID:11088401

  6. Dynamics of optical breakdown in air induced by single and double nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Mahdieh, Mohammad Hossein; Akbari Jafarabadi, Marzieh

    2015-12-01

    In this paper, an optical breakdown in air induced by single and double nanosecond laser pulses was studied. A high power Nd:YAG laser beam was used for producing optical breakdown plasma in the air. The dynamics of breakdown plasma were studied using an optical probe beam. A portion of the laser beam was used, as the probe beam and was aligned to propagate (perpendicular to the pump beam) through the breakdown region. The transmission of the probe beam (through the breakdown region) was temporally measured for both single and double pulse irradiations. The results were used to describe the evolution of the induced plasma in both conditions. These results show that the plasma formation time and its absorptivity are strongly dependent on the single or double pulse configurations.

  7. Pulse-mode quantum projection synthesis: Effects of mode mismatch on optical state truncation and preparation

    SciTech Connect

    Oezdemir, Sahin Kaya; Koashi, Masato; Miranowicz, Adam; Imoto, Nobuyuki

    2002-11-01

    Quantum projection synthesis can be used for phase-probability-distribution measurement and optical-state truncation and preparation. The method relies on interfering optical light beams, which is a major challenge in experiments performed by pulsed light sources. In the pulsed regime, the time frequency overlap of the interfering light beams has a major impact on the efficiency of the method. In this paper, the pulse-mode projection-synthesis approach is developed, the mode structures of interfering light beams are characterized, and the effect of this overlap on the fidelity of optical-state truncation and preparation is investigated. By introducing the positive-operator-valued measure for the detection events in the scheme, the effect of mode mismatch between the photon-counting detectors and the incident light beams is also presented.

  8. Dynamics of optical breakdown in air induced by single and double nanosecond laser pulses

    SciTech Connect

    Mahdieh, Mohammad Hossein Akbari Jafarabadi, Marzieh

    2015-12-15

    In this paper, an optical breakdown in air induced by single and double nanosecond laser pulses was studied. A high power Nd:YAG laser beam was used for producing optical breakdown plasma in the air. The dynamics of breakdown plasma were studied using an optical probe beam. A portion of the laser beam was used, as the probe beam and was aligned to propagate (perpendicular to the pump beam) through the breakdown region. The transmission of the probe beam (through the breakdown region) was temporally measured for both single and double pulse irradiations. The results were used to describe the evolution of the induced plasma in both conditions. These results show that the plasma formation time and its absorptivity are strongly dependent on the single or double pulse configurations.

  9. Integration of nonlinearity-management and dispersion-management for pulses in fiber-optic links

    NASA Astrophysics Data System (ADS)

    Driben, Rodislav; Malomed, Boris A.; Mahlab, Uri

    2004-03-01

    We introduce a model of a long-haul fiber-optic link that uses a combination of the nonlinearity- and dispersion-compensation (management) to stabilize nonsoliton pulses. The compensation of the accumulated fiber nonlinearity, and simultaneously pulse reshaping, which helps to suppress the inter-symbol interference (ISI, i.e., blurring of blank spaces between adjacent pulses), are performed by second-harmonic-generating modules, which are periodically inserted together with amplifiers. We demonstrate that the dispersion-management (DM), which was not included in an earlier considered model, drastically improves stability of the pulses. The stable-transmission length for an isolated pulse, which was less than 10 fiber spans with the use of the nonlinearity-management only, becomes indefinitely long. It is demonstrated too that the pulse is quite robust against fluctuations of its initial parameters, and the scheme operates efficiently in a very broad parameter range. The interaction between pulses can be safely suppressed for the transmission distance exceeding 16 spans (≃1000 km). The smallest temporal separation between adjacent pulses, which is necessary to prevent the ISI, attains a minimum in the case of moderate DM, similar to known results for the DM solitons. The mutually-induced distortion of co-propagating pulses being accounted for by the emission of radiation, a plausible way to further increase the stable-transmission limit is to introduce bandpass filters.

  10. Temporal broadening of optical pulses propagating through non-Kolmogorov turbulence.

    PubMed

    Chen, Chunyi; Yang, Huamin; Lou, Yan; Tong, Shoufeng; Liu, Rencheng

    2012-03-26

    General formulations of the temporal averaged pulse intensity for optical pulses propagating through either non-Kolmogorov or Kolmogorov turbulence are deduced under the strong fluctuation conditions and the narrow-band assumption. Based on these formulations, an analytical formula for the turbulence-induced temporal half-width of spherical-wave Gaussian (SWG) pulses is derived, and the single-point, two-frequency mutual coherence function (MCF) of collimated Gaussian-beam waves in atmospheric turbulence is formulated analytically, by which the temporal averaged pulse intensity of collimated space-time Gaussian (CSTG) pulses can be calculated numerically. Calculation results show that the temporal broadening of both SWG and CSTG pulses in atmospheric turbulence depends heavily on the general spectral index of the spatial power spectrum of refractive-index fluctuations, and the temporal broadening of SWG pulses can be used to approximate that of CSTG pulses on the axis with the same turbulence parameters and propagation distances. It is also illustrated by numerical calculations that the variation in the turbulence-induced temporal half-width of CSTG pulses with the radial distance is really tiny. PMID:22453453