Showing papers on "Ultrashort pulse published in 2006"
TL;DR: The availability of single-cycle isolated attosecond pulses opens the way to a new regime in ultrafast physics, in which the strong-field electron dynamics in atoms and molecules is driven by the electric field of the attose Cond pulses rather than by their intensity profile.
Abstract: We generated single-cycle isolated attosecond pulses around ∼36 electron volts using phase-stabilized 5-femtosecond driving pulses with a modulated polarization state. Using a complete temporal characterization technique, we demonstrated the compression of the generated pulses for as low as 130 attoseconds, corresponding to less than 1.2 optical cycles. Numerical simulations of the generation process show that the carrier-envelope phase of the attosecond pulses is stable. The availability of single-cycle isolated attosecond pulses opens the way to a new regime in ultrafast physics, in which the strong-field electron dynamics in atoms and molecules is driven by the electric field of the attosecond pulses rather than by their intensity profile.
1,386 citations
TL;DR: In this article, a technique that uses high-order harmonic generation in molecules to probe nuclear dynamics and structural rearrangement on a sub-femtosecond time scale was demonstrated.
Abstract: We demonstrate a technique that uses high-order harmonic generation in molecules to probe nuclear dynamics and structural rearrangement on a subfemtosecond time scale. The chirped nature of the electron wavepacket produced by laser ionization in a strong field gives rise to a similar chirp in the photons emitted upon electron-ion recombination. Use of this chirp in the emitted light allows information about nuclear dynamics to be gained with 100-attosecond temporal resolution, from excitation by an 8-femtosecond pulse, in a single laser shot. Measurements on molecular hydrogen and deuterium agreed well with calculations of ultrafast nuclear dynamics in the H2+ molecule, confirming the validity of the method. We then measured harmonic spectra from CH4 and CD4 to demonstrate a few-femtosecond time scale for the onset of proton rearrangement in methane upon ionization.
664 citations
TL;DR: In this paper, a photonic crystal nanocavity laser with response times as short as a few picoseconds resulting from 75-fold spontaneous emission rate enhancement in the cavity was demonstrated.
Abstract: Spontaneous emission is not inherent to an emitter, but rather depends on its electromagnetic environment. In a microcavity, the spontaneous emission rate can be greatly enhanced compared with that in free space. This so-called Purcell effect can dramatically increase laser modulation speeds, although to date no time-domain measurements have demonstrated this. Here we show extremely fast photonic crystal nanocavity lasers with response times as short as a few picoseconds resulting from 75-fold spontaneous emission rate enhancement in the cavity. We demonstrate direct modulation speeds far exceeding 100 GHz (limited by the detector response time), already more than an order of magnitude above the fastest semiconductor lasers. Such ultrafast, efficient, and compact lasers show great promise for applications in high-speed communications, information processing, and on-chip optical interconnects.
618 citations
TL;DR: A modelocked ytterbium (Yb)-doped fiber laser that is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the cavity is demonstrated.
Abstract: A modelocked Yb-doped fiber laser without an anomalous dispersive segment is demonstrated. Pulse-shaping is based on spectral filtering of a highly-chirped pulse in the cavity. The laser generated 170-fs pulses with 3-nJ pulse energy. Article not available.
502 citations
TL;DR: The marriage of UltraFast and UltraStable lasers was brokered mainly by two international teams and became exciting when a special "designer'' microstructure optical fiber was shown to be nonlinear enough to produce white light from the femtosecond laser pulses, such that the output spectrum embraced a full optical octave as mentioned in this paper.
Abstract: Four long-running currents in laser technology met and merged in 1999--2000. Two of these were the quest toward a stable repetitive sequence of ever-shorter optical pulses and, on the other hand, the quest for the most time-stable, unvarying optical frequency possible. The marriage of UltraFast and UltraStable lasers was brokered mainly by two international teams and became exciting when a special ``designer'' microstructure optical fiber was shown to be nonlinear enough to produce ``white light'' from the femtosecond laser pulses, such that the output spectrum embraced a full optical octave. Then, for the first time, one could realize an optical frequency interval equal to the comb's lowest frequency, and count out this interval as a multiple of the repetition rate of the femtosecond pulse laser. This ``gear-box'' connection between the radio frequency standard and any/all optical frequency standards came just as Sensitivity-Enhancing ideas were maturing. The four-way Union empowered an explosion of accurate frequency measurement results in the standards field and prepares the way for refined tests of some of our cherished physical principles, such as the time-stability of some of the basic numbers in physics (e.g., the ``fine-structure'' constant, the speed of light, certain atomic mass ratios etc.), and the equivalence of time-keeping by clocks based on different physics. The stable laser technology also allows time-synchronization between two independent femtosecond lasers so exact they can be made to appear as if the source were a single laser. By improving pump/probe experiments, one important application will be in bond-specific spatial scanning of biological samples. This next decade in optical physics should be a blast.
492 citations
TL;DR: In this article, the authors review the mechanisms of and techniques for bulk modification of transparent materials using femtosecond laser pulses and discuss the fabrication of photonic and other structures in transparent materials, including waveguides, couplers, gratings, diffractive lenses, optical data storage and microfluidic channels.
Abstract: When a femtosecond laser pulse is focused inside a transparent material, the optical intensity in the focal volume can become high enough to induce permanent structural modifications such as a refractive index change or the formation of a small vacancy. Thus, one can micromachine structures inside the bulk of a transparent material in three dimensions. We review the mechanisms of and techniques for bulk modification of transparent materials using femtosecond laser pulses and discuss the fabrication of photonic and other structures in transparent materials, including waveguides, couplers, gratings, diffractive lenses, optical data storage, and microfluidic channels.
413 citations
TL;DR: In this paper, the physical principles of ultrashort pulse generation in VECSELs are discussed, considering the role played by the semiconductor quantum well gain structure, and the saturable absorber.
402 citations
TL;DR: In this paper, the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence.
Abstract: Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range [1-4]. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL) [5-10]. Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important milestone towards a user facility designed for wavelengths down to 6 nm. With a peak brilliance exceeding the state-of-the-art of synchrotron radiation sources [4] by seven orders of magnitude, this device opens a new field of experiments, and it paves the way towards sources with even shorter wavelengths, such as the Linac Coherent Light Source [3] at Stanford, USA, and the European X-ray Free Electron Laser Facility [4] in Hamburg, Germany.
353 citations
TL;DR: In this paper, a low-intensity (<10−3) second-harmonic beam with the fundamental beam is used to perturb the production process without significantly modifying it, and the attosecond-pulse duration is read from the modulation of the evenharmonic signal as a function of the two-field delay.
Abstract: Generating attosecond pulses has required a radically different approach from previous ultrafast optical methods. The technology of attosecond measurement, however, is built on established methods of characterizing femtosecond pulses: the pulse is measured after it has left the region where it was produced. We offer a completely different approach: in situ measurement. That is, we integrate attosecond-pulse production and measurement in a manner that can be applied to many high-order nonlinear interactions. To demonstrate this approach, we combine a low-intensity (<10−3) second-harmonic beam with the fundamental beam, to gently perturb the production process without significantly modifying it. The attosecond-pulse duration is read from the modulation of the even-harmonic signal as a function of the two-field delay. Increasing the second-harmonic intensity slightly (<10−2), we extend measurement to control. We demonstrate control by manipulating the high-harmonic spectrum with high efficiency.
328 citations
TL;DR: This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source, and allows selection of a desired range out of the spectrum of the polyenergetic proton beam.
Abstract: We present a technique for simultaneous focusing and energy selection of high-current, mega–electron volt proton beams with the use of radial, transient electric fields (10 7 to 10 10 volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.
315 citations
TL;DR: This work demonstrated intensity modulation of light with light in a silicon–polymer waveguide device, based on the all-optical Kerr effect—the ultrafast effect used in four-wave mixing, and showed experimentally that the mechanism of this modulation is ultrafast through spectral measurements.
Abstract: Although gigahertz-scale free-carrier modulators have been demonstrated in silicon, intensity modulators operating at terahertz speeds have not been reported because of silicon's weak ultrafast nonlinearity. We have demonstrated intensity modulation of light with light in a silicon–polymer waveguide device, based on the all-optical Kerr effect—the ultrafast effect used in four-wave mixing. Direct measurements of time-domain intensity modulation are made at speeds of 10 GHz. We showed experimentally that the mechanism of this modulation is ultrafast through spectral measurements, and that intensity modulation at frequencies in excess of 1 THz can be obtained. By integrating optical polymers through evanescent coupling to silicon waveguides, we greatly increase the effective nonlinearity of the waveguide, allowing operation at continuous-wave power levels compatible with telecommunication systems. These devices are a first step in the development of large-scale integrated ultrafast optical logic in silicon, and are two orders of magnitude faster than previously reported silicon devices.
TL;DR: In this article, the advances in x-ray femtosecond pulse generation and the most recent discoveries in the field of ultrashort (femto-cond) xray science are presented.
Abstract: We present the advances in x-ray femtosecond pulse generation and the most recent discoveries in the field of ultrashort (femtosecond) x-ray science. Nowadays x-rays show their potential not only when it comes to resolving atomic spatial scale but also the inherent temporal scale of quantum dynamics in atoms, molecules and solids. We discuss ultrafast x-ray sources that are currently used to generate femtosecond duration pulses of soft and hard x-ray radiation. Several techniques of x-ray pulse characterization are presented along with a method to control the shape of coherent soft x-rays. A large number of experiments using femtosecond x-ray pulses have been conducted recently and we review some of them. The field of ultrafast x-ray science draws its strength from the large variety of different sources of femtosecond duration x-ray pulses that are complementary rather than competing.
TL;DR: An experimental and numerical study of electron emission from a sharp tungsten tip triggered by sub-8-fs low-power laser pulses shows that electron emission takes place within less than one optical period of the exciting laser pulse, so that an 8 fs 800 nm laser pulse is capable of producing a single electron pulse of less than 1 fs duration.
Abstract: We present an experimental and numerical study of electron emission from a sharp tungsten tip triggered by sub-8-fs low-power laser pulses. This process is nonlinear in the laser electric field, and the nonlinearity can be tuned via the dc voltage applied to the tip. Numerical simulations of this system show that electron emission takes place within less than one optical period of the exciting laser pulse, so that an 8 fs 800 nm laser pulse is capable of producing a single electron pulse of less than 1 fs duration. Furthermore, we find that the carrier-envelope phase dependence of the emission process is smaller than 0.1% for an 8 fs pulse but is steeply increasing with decreasing laser pulse duration.
TL;DR: In this article, the authors discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field and discuss a broad class of femtosecond laser systems with output power ranging from a few gigawatts to hundreds of terawatts, with the potential of generating few-optical-cycle pulses at the petawatt power level.
Abstract: Since the proof-of-principle demonstration of optical parametric amplifier to efficiently amplify chirped pulses in 1992, optical parametric chirped pulse amplification (OPCPA) became a widely recognized and rapidly developing technique for high-power femtosecond pulse generation. In the meantime, we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers. These systems cover a broad class of femtosecond lasers, with output power ranging from a few gigawatts to hundreds of terawatts, with a potential of generating few-optical-cycle pulses at the petawatt power level. In this paper, we discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field.
TL;DR: In this article, the authors have demonstrated intensity modulation of light with light in a silicon-polymer integrated waveguide device, based on the all-optical Kerr effect -the same ultrafast effect used in four-wave mixing.
Abstract: Although Gigahertz-scale free-carrier modulators have been previously demonstrated in silicon, intensity modulators operating at Terahertz speeds have not been reported because of silicon's weak ultrafast optical nonlinearity. We have demonstrated intensity modulation of light with light in a silicon-polymer integrated waveguide device, based on the all-optical Kerr effect - the same ultrafast effect used in four-wave mixing. Direct measurements of time-domain intensity modulation are made at speeds of 10 GHz. We showed experimentally that the ultrafast mechanism of this modulation functions at the optical frequency through spectral measurements, and that intensity modulation at frequencies in excess of 1 THz can be obtained in this device. By integrating optical polymers through evanescent coupling to high-mode-confinement silicon waveguides, we greatly increase the effective nonlinearity of the waveguide for cross-phase modulation. The combination of high mode confinement, multiple integrated optical components, and high nonlinearities produces all-optical ultrafast devices operating at continuous-wave power levels compatible with telecommunication systems. Although far from commercial radio frequency optical modulator standards in terms of extinction, these devices are a first step in development of large-scale integrated ultrafast optical logic in silicon, and are two orders of magnitude faster than previously reported silicon devices.
TL;DR: A novel method for generating few-cycle pulses with extremely high peak powers >100 GW is experimentally demonstrated and relies on plasma-induced spectral broadening and does not require any additional means for dispersion compensation.
Abstract: We demonstrate a novel technique for pulse compression of few-millijoule pulses with shorter than 10 fs duration. Our technique relies on spectral broadening in a white-light filament generated in a noble gas. In this filament we observe self-compression of 45 fs pulses down to below 8 fs duration without the need for any additional dispersion compensation. Using input pulses of 5 mJ, we generate compressed pulses with up to 3.8 mJ pulse energy. Therefore this method is much more efficient than previously demonstrated compression schemes. The generated peak powers of more than 100 GW at a kilohertz repetition rate open up a perspective for compression of few-cycle pulses with energies well beyond the capacity of hollow-fiber compressors.
TL;DR: In this paper, the challenges, achievements, and perspectives of ultrashort pulse generation and amplification in fibers are reviewed, as well as novel experimental strategies and fiber designs offer an enormous potential toward laser systems with high average powers and high pulse energies.
Abstract: The recent demonstration of rare-earth-doped fiber lasers with a continuous wave output power well above the kilowatt level with diffraction-limited beam quality has proven that fiber lasers constitute a power-scalable solid-state laser concept. To generate intense pulses from a fiber, several fundamental limitations have to be overcome. Nevertheless, novel experimental strategies and fiber designs offer an enormous potential toward laser systems with high average powers and high pulse energies. This paper reviews the challenges, achievements, and perspectives of ultrashort pulse generation and amplification in fibers.
TL;DR: Because of the spatial separation of the CARS output signal relative to the three input beams inherent in a folded BOXCARS arrangement, this technique is particularly amenable to probing low-frequency vibrational modes, which play a significant role in accepting vibrational energy during intramolecular vibrationalenergy redistribution within electronically excited states.
Abstract: The development of a time-resolved coherent anti-Stokes Raman scattering (CARS) variant for use as a probe of excited electronic state Raman-active modes following excitation with an ultrafast pump pulse is detailed. Application of this technique involves a combination of broadband fs-time scale pulses and a narrowband pulse of ps duration that allows multiplexed detection of the CARS signal, permitting direct observation of molecular Raman frequencies and intensities with time resolution dictated by the broadband pulses. Thus, this nonlinear optical probe, designated fs/ps CARS, is suitable for observation of Raman spectral evolution following excitation with a pump pulse. Because of the spatial separation of the CARS output signal relative to the three input beams inherent in a folded BOXCARS arrangement, this technique is particularly amenable to probing low-frequency vibrational modes, which play a significant role in accepting vibrational energy during intramolecular vibrational energy redistribution within electronically excited states. Additionally, this spatial separation allows discrimination against strong fluorescence signal, as demonstrated in the case of rhodamine 6G.
TL;DR: Tunable and stable ultrashort Laser pulses in the visible spectrum are generated with high efficiency by four-wave mixing process during the filamentation of near-infrared and infrared laser pulses in gases.
Abstract: Tunable and stable ultrashort laser pulses in the visible spectrum are generated with high efficiency by four-wave mixing process during the filamentation of near-infrared and infrared laser pulses in gases. It is shown that these tunable ultrashort pulses have a very low energy fluctuation and an excellent mode quality due to the processes of intensity clamping and self-filtering in the filament.
TL;DR: The dynamical behavior of excess protons in liquid water is investigated using femtosecond vibrational pump-probe spectroscopy and the interconversion between the H9O4 (Eigen) and H5O2(+) (Zundel) hydration structures of the proton is observed.
Abstract: The dynamical behavior of excess protons in liquid water is investigated using femtosecond vibrational pump-probe spectroscopy. By resonantly exciting the O-H+-stretching mode of the H9O4(+) (Eigen) hydration structure of the proton and probing the subsequent absorption change over a broad frequency range, the dynamics of the proton is observed in real time. The lifetime of the protonic stretching mode is found to be approximately 120 fs, shorter than for any other vibration in liquid water. We also observe the interconversion between the H9O4(+) (Eigen) and H5O2(+) (Zundel) hydration structures of the proton. This interconversion, which constitutes an essential step of proton transport in water, is found to occur on an extremely fast (< 100 fs) time scale.
TL;DR: It is shown that for sufficiently short optical pulses, with a pulsewidth much shorter than the inverse terahertz frequency, conversion efficiency does not depend on pulse duration, and that when the group velocity dispersion of optical pulses is small, one can substantially exceed Manley -Rowe conversion limit due to cascaded processes.
Abstract: We explore optical-to-terahertz conversion efficiencies which can be achieved with femto- and picosecond optical pulses in electro-optic crystals with periodically inverted sign of second-order susceptibility. Optimal crystal lengths, pulse durations, pulse formats and focusing are regarded. We show that for sufficiently short (femtosecond) optical pulses, with a pulsewidth much shorter than the inverse terahertz frequency, conversion efficiency does not depend on pulse duration. We also show that by mixing two picosecond pulses (bandwidth-limited or chirped), one can achieve conversion efficiency, which is the same as in the case of femtosecond pulse with the same pulse energy. Additionally, when the group velocity dispersion of optical pulses is small, one can substantially exceed Manley‒Rowe conversion limit due to cascaded processes.
TL;DR: A noncollinear optical parametric chirped pulse amplifier system that produces 7.6 fs pulses with a peak power of 2 terawatt at 30 Hz repetition rate is demonstrated.
Abstract: We demonstrate a noncollinear optical parametric chirped pulse amplifier system that produces 7.6 fs pulses with a peak power of 2 terawatt at 30 Hz repetition rate. Using an ultra-broadband Ti:Sapphire seed oscillator and grating-based stretching and compression combined with an LCD phase-shaper, we amplify a 310 nm wide spectrum with a total gain of 3×107, and compress it within 5% of its Fourier limit. The total integrated parametric fluorescence is kept below 0.2%, leading to a pre-pulse contrast of 2×10-8 on picosecond timescales.
TL;DR: The ultrafast nonlinear optical response of a single metal nanoparticle is investigated by combining a high-sensitivity femtosecond pump-probe setup with a spatial modulation microscope and its dependence on the electronic temperature is quantitatively interpreted using the two-temperature model.
Abstract: The ultrafast nonlinear optical response of a single metal nanoparticle is investigated by combining a high-sensitivity femtosecond pump-probe setup with a spatial modulation microscope. Experiments are performed on 20 and 30 nm silver nanospheres, in situ characterized via their optical linear extinction spectrum. The measured transient response permits investigation of the electron-phonon energy transfer time in a single nanoparticle. Its dependence on the electronic temperature is quantitatively interpreted using the two-temperature model.
TL;DR: In this article, the authors describe an ultrafast spectroscopy system based on two synchronized noncollinear optical parametric amplifiers (NOPAs), which can be independently configured to generate ultrabroadband sub-10fs visible pulses, tunable 15-30fs near-infrared pulses (900-1500nm), and 15-20fs blue pulses (430-480nm).
Abstract: We describe an ultrafast spectroscopy system based on two synchronized noncollinear optical parametric amplifiers (NOPAs). Each NOPA can be independently configured to generate ultrabroadband sub-10fs visible pulses, tunable 15fs visible pulses (500–720nm), tunable 15–30fs near-infrared pulses (900–1500nm), and 15–20fs blue pulses (430–480nm). This system enables to perform pump-probe experiments over nearly two octaves of spectrum with unprecedented temporal resolution. We present application examples highlighting the capability of this instrument to track excited-state dynamics occurring on the sub-100fs time scale: electron transfer in polymer-fullerene blends, intersubband energy relaxation in carbon nanotubes, and internal conversion in carotenoids.
TL;DR: In this paper, the authors presented a method for approximating the measured spectrum of pulsed signals in the high and low pulse-repetition-frequency (PRF) region.
Abstract: This paper presents calculations for approximating the measured spectrum of pulsed signals in the high and low pulse-repetition-frequency (PRF) region. Experimentally verified peak and average power calculations are presented for pulse trains with no modulation and when modulated by random data using binary phase-shift keying (BPSK). A pulse generator is presented that is built using commercially available discrete components. BPSK pulses are generated at a PRF of 50 MHz. The output spectrum has a center frequency of 5.355 GHz and a -10-dB bandwidth of 550 MHz. A technique for pulse shaping is presented that approximates a Gaussian pulse by exploiting the exponential behavior of a bipolar junction transistor. This technique is demonstrated by a pulse generator fabricated in a 0.18-/spl mu/m SiGe BiCMOS process. BPSK pulses are generated by inverting a local oscillator signal as opposed to the reference pulse, improving matching. Pulses are transmitted at a PRF of 100 MHz and centered in 528-MHz-wide channels equally spaced within the 3.1-10.6-GHz ultra-wideband band. Measurement results for both transmitters match well with calculated values.
TL;DR: A previously undescribed spectroscopic probe that makes use of electrons rescattered during the process of high-order harmonic generation using impulsive stimulated Raman scattering with a short laser pulse is reported.
Abstract: We report a previously undescribed spectroscopic probe that makes use of electrons rescattered during the process of high-order harmonic generation. We excite coherent vibrations in SF6 using impulsive stimulated Raman scattering with a short laser pulse. A second, more intense laser pulse generates high-order harmonics of the fundamental laser, at wavelengths of ≈20–50 nm. The high-order harmonic yield is observed to oscillate, at frequencies corresponding to all of the Raman-active modes of SF6, with an asymmetric mode most visible. The data also show evidence of relaxation dynamics after impulsive excitation of the molecule. Theoretical modeling indicates that the high harmonic yield should be modulated by both Raman and infrared-active vibrational modes. Our results indicate that high harmonic generation is a very sensitive probe of vibrational dynamics and may yield more information simultaneously than conventional ultrafast spectroscopic techniques. Because the de Broglie wavelength of the recolliding electron is on the order of interatomic distances, i.e., ≈1.5 A, small changes in the shape of the molecule lead to large changes in the high harmonic yield. This work therefore demonstrates a previously undescribed spectroscopic technique for probing ultrafast internal dynamics in molecules and, in particular, on the chemically important ground-state potential surface.
TL;DR: The phase stability of the shaped pulse proved sufficient for cross correlation with unshaped mid-IR pulses, and phase- and amplitude-tailored pulses can now be readily incorporated into phase-sensitive experiments, such as heterodyned 2D IR spectroscopy.
Abstract: Pulse shaping directly in the mid-IR is accomplished by using a germanium acousto-optic modulator (Ge AOM) capable of programmable phase and amplitude modulation for IR light between 2 and 18 μm. Shaped waveforms centered at 4.9 μm are demonstrated in both the frequency and the time domains. With a 50% throughput efficiency, the Ge AOM can generate much more intense pulses with higher resolution than can indirect shaping methods. Furthermore, the phase stability of the shaped pulse proved sufficient for cross correlation with unshaped mid-IR pulses. Thus, phase- and amplitude-tailored pulses can now be readily incorporated into phase-sensitive experiments, such as heterodyned 2D IR spectroscopy.
TL;DR: In this article, coherent optical control of the magnetization in ferrimagnetic garnet films on the femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses was demonstrated.
Abstract: We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on the femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites while circularly polarized pulses additionally act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. Due to the slow phonon-magnon interaction in these dielectrics, thermal effects of the laser excitation are clearly distinguished from the ultrafast nonthermal effects and can be seen only on the time scale of nanoseconds for sample temperatures near the Curie point. The reported effects open exciting possibilities for ultrafast manipulation of spins by light, and provide insight into the physics of magnetism on ultrafast time scales.
TL;DR: In this paper, the authors present a survey of optical instrumentation based on the concept of space-time duality, including a time-lens timing-jitter compensator for ultralonghaul dense-wavelength-division-multiplexed dispersion-managed soliton transmission.
Abstract: The last two decades have seen a wealth of optical instrumentation based upon the concepts of space-time duality. A historical overview of how this beautiful framework has been exploited to develop instruments for optical signal processing is presented. The power of this framework is then demonstrated by reviewing four devices in detail based upon space-time dualities that have been experimentally demonstrated: 1) a time-lens timing-jitter compensator for ultralong-haul dense-wavelength-division-multiplexed dispersion-managed soliton transmission, 2) a multiwavelength pulse generator using time-lens compression, 3) a programmable ultrafast optical delay line by use of a time-prism pair, and 4) an enhanced ultrafast optical delay line by use of soliton propagation between a time-prism pair.
TL;DR: In this article, an improved two-dimensional optical scanning technique combined with an ultrafast Sagnac interferometer for delayed-probe imaging of surface wave propagation is described.
Abstract: We describe an improved two-dimensional optical scanning technique combined with an ultrafast Sagnac interferometer for delayed-probe imaging of surface wave propagation. We demonstrate the operation of this system, which involves the use of a single focusing objective, by monitoring surface acoustic wave propagation on opaque substrates with picosecond temporal and micron lateral resolutions. An improvement in the lateral resolution by a factor of 3 is achieved in comparison with previous setups for similar samples.