Showing papers on "Femtosecond pulse shaping published in 2011"
TL;DR: In this paper, a tutorial on the field of femtosecond pulse shaping, a technology that enables generation of nearly arbitrary, user defined, ultrafast optical waveforms, with control of phase, amplitude, and polari-zation, is presented.
579 citations
TL;DR: In this paper, a comparative study of the ablation of metal with micro-, nano-, pico-and femtosecond laser pulses was presented, where the authors attributed the generally lower medium laser power of the ultrafast laser systems, on the other hand to the changed ablation mechanisms.
323 citations
TL;DR: In this paper, techniques to generate microwave arbitrary waveforms based on all-fiber solutions are reviewed, with an emphasis on the system architectures based on direct space-to-time pulse shaping, spectral-shaping and wavelength to-time mapping, temporal pulse shaping and photonic microwave delay-line filtering.
249 citations
TL;DR: This approach shows that a multiply scattering medium can be put to profit for light manipulation at the femtosecond scale, and has a diverse range of potential applications that includes quantum control, biological imaging and photonics.
Abstract: Pulses of light propagating through multiply scattering media undergo complex spatial and temporal distortions to form the familiar speckle pattern. There is much current interest in both the fundamental properties of speckles and the challenge of spatially and temporally refocusing behind scattering media. Here we report on the spatially and temporally resolved measurement of a speckle field produced by the propagation of an ultrafast optical pulse through a thick strongly scattering medium. By shaping the temporal profile of the pulse using a spectral phase filter, we demonstrate the spatially localized temporal recompression of the output speckle to the Fourier-limit duration, offering an optical analogue to time-reversal experiments in the acoustic regime. This approach shows that a multiply scattering medium can be put to profit for light manipulation at the femtosecond scale, and has a diverse range of potential applications that includes quantum control, biological imaging and photonics.
203 citations
TL;DR: In this article, single-molecule techniques and femtosecond pulse shaping are combined to investigate quantum coherence in biomolecules, and the creation and manipulation of such coherence enables a basic single-qubit operation with terrylene diimide at room temperature.
Abstract: Single-molecule techniques and femtosecond pulse shaping are now combined to investigate quantum coherence in biomolecules. The creation and manipulation of such coherence enables a basic single-qubit operation with terrylene diimide at room temperature.
152 citations
TL;DR: In this paper, a semiconductor disk laser based on an InGaAs/AlGaAs quantum-well gain medium was mode-locked by a fast semiconductor saturable absorber mirror.
Abstract: A semiconductor disk laser based on an InGaAs/AlGaAs quantum-well gain medium was mode-locked by a fast semiconductor saturable absorber mirror. By high-order harmonic mode-locking a 92 GHz pulse train was obtained with a pulse duration of <200 fs. In order to achieve fundamental mode-locking, too strong saturation of the semiconductor elements had to be avoided. In a single-pulse regime, pulses shorter than 110 fs were generated at a wavelength of 1030 nm.
135 citations
TL;DR: A nearly in situ single-shot measurement of the x-ray pulse arrival time relative to the ultra-short optical pulse is demonstrated.
Abstract: We present a new technique for measuring the relative delay between a soft x-ray FEL pulse and an optical laser that indicates a sub 25 fs RMS measurement error. An ultra-short x-ray pulse photo-ionizes a semiconductor (Si3N4) membrane and changes the optical transmission. An optical continuum pulse with a temporally chirped bandwidth spanning 630 nm – 710 nm interacts with the membrane such that the timing of the x-ray pulse can be determined from the onset of the spectral modulation of the transmitted optical pulse. This experiment demonstrates a nearly in situ single-shot measurement of the x-ray pulse arrival time relative to the ultra-short optical pulse.
134 citations
TL;DR: By 3D particle-in-cell simulation and analysis, a plasma lens is proposed to make high intensity, high contrast laser pulses with a steep front to improve the laser contrast without affecting laser shaping of the main pulse.
Abstract: By 3D particle-in-cell simulation and analysis, we propose a plasma lens to make high intensity, high contrast laser pulses with a steep front. When an intense, short Gaussian laser pulse of circular polarization propagates in near-critical plasma, it drives strong currents of relativistic electrons which magnetize the plasma. Three pulse shaping effects are synchronously observed when the laser passes through the plasma lens. The laser intensity is increased by more than 1 order of magnitude while the initial Gaussian profile undergoes self-modulation longitudinally and develops a steep front. Meanwhile, a nonrelativistic prepulse can be absorbed by the overcritical plasma lens, which can improve the laser contrast without affecting laser shaping of the main pulse. If the plasma skin length is properly chosen and kept fixed, the plasma lens can be used for varied laser intensity above 10(19) W/cm(2).
118 citations
TL;DR: Measurements show that the contrast ratio of the main laser pulse is around 10(10) within the time scale of -400 ps and the duration of compressed pulse is 27.9 fs, corresponding to a peak power of 1.16 PW.
Abstract: Based on a combined scheme of doubled chirped-pulse amplification and a femtosecond noncollinear optical-parametric amplifier, a high-contrast femtosecond laser pulse with energy of up to 32.3 J has been generated by improving the gain efficiency and boosting the pump energy to 120 J in the final amplifier. Our measurements show that the contrast ratio of the main laser pulse is around 1010 within the time scale of −400 ps and the duration of compressed pulse is 27.9 fs, corresponding to a peak power of 1.16 PW.
110 citations
TL;DR: In this article, an x-ray-optical cross-correlation technique was proposed to determine the duration of femtosecond (>40?fs) x-rays from the Linac Coherent Light Source (LCLS).
Abstract: Two-color, single-shot time-of-flight electron spectroscopy of atomic neon was employed at the Linac Coherent Light Source (LCLS) to measure laser-assisted Auger decay in the x-ray regime. This x-ray-optical cross-correlation technique provides a straightforward, non-invasive and on-line means of determining the duration of femtosecond (>40?fs) x-ray pulses. In combination with a theoretical model of the process based on the soft-photon approximation, we were able to obtain the LCLS pulse duration and to extract a mean value of the temporal jitter between the optical pulses from a synchronized Ti-sapphire laser and x-ray pulses from the LCLS. We find that the experimentally determined values are systematically smaller than the length of the electron bunches. Nominal electron pulse durations of 175 and 75?fs, as provided by the LCLS control system, yield x-ray pulse shapes of 120?20?fs full-width at half-maximum (FWHM) and an upper limit of 40?20?fs FWHM, respectively. Simulations of the free-electron laser agree well with the experimental results.
108 citations
TL;DR: An efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths is developed, using the exciton states of a semiconductor nanostructure as a working example.
Abstract: We have developed an efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths. The two major components of the largely automated device are a spatial beam shaper which controls the beam geometry and a spatiotemporal pulse shaper which controls the temporal waveform of the femtosecond pulse in each beam. We describe how to construct, calibrate, and operate the device, and we discuss its limitations. We use the exciton states of a semiconductor nanostructure as a working example. A series of complex multidimensional spectra—displayed in amplitude and real parts—reveals increasingly intricate correlations among the excitons.
TL;DR: An experimental and theoretical study of the creation of plasma and the resulting spatiotemporal distortions of the driving laser pulse are presented and their implications for power scaling of intracavity high-order harmonic generation and extreme ultraviolet frequency combs are discussed.
Abstract: Intrinsic to the process of high-order harmonic generation is the creation of plasma and the resulting spatiotemporal distortions of the driving laser pulse. Inside a high-finesse cavity where the driver pulse and gas medium are reused, this can lead to optical bistability of the cavity-plasma system, accumulated self-phase modulation of the intracavity pulse, and coupling to higher-order cavity modes. We present an experimental and theoretical study of these effects and discuss their implications for power scaling of intracavity high-order harmonic generation and extreme ultraviolet frequency combs.
TL;DR: In an all-optical experiment, coherent control of ultrafast electron dynamics via photon locking by temporal phase discontinuities on a few attosecond timescale is demonstrated.
Abstract: We investigate the temporal precision in the generation of ultrashort laser pulse pairs by pulse shaping techniques. To this end, we combine a femtosecond polarization pulse shaper with a polarizer and employ two linear spectral phase masks to mimic an ultrastable common-path interferometer. In an all-optical experiment we study the interference signal resulting from two temporally delayed pulses. Our results show a 2σ-precision of 300 zs = 300 × 10−21 s in pulse-to-pulse delay. The standard deviation of the mean is 11 zs. The obtained precision corresponds to a variation of the arm’s length in conventional delay stage based interferometers of 0.45 A. We apply these precisely generated pulse pairs to a strong-field quantum control experiment. Coherent control of ultrafast electron dynamics via photon locking by temporal phase discontinuities on a few attosecond timescale is demonstrated.
TL;DR: The technique expands upon the recent work of Wittmann and incorporates a stereographic above-threshold laser-induced ionization measurement and electronics optimized to produce a signal corresponding to the carrier-envelope phase within microseconds of the laser interaction, thereby facilitating data-tagging and feedback applications.
Abstract: In this Letter we demonstrate a method for real-time determination of the carrier-envelope phase of each and every single ultrashort laser pulse at kilohertz repetition rates. The technique expands upon the recent work of Wittmann and incorporates a stereographic above-threshold laser-induced ionization measurement and electronics optimized to produce a signal corresponding to the carrier-envelope phase within microseconds of the laser interaction, thereby facilitating data-tagging and feedback applications. We achieve a precision of 113 mrad (6.5°) over the entire 2π range.
TL;DR: In this article, a low-power beam of repetitive broadband THz pulses was transmitted through the atmosphere with 51% relative humidity at 21°C and the measured transmitted pulses reshaped from a 0.5-ps input pulse into an output pulse structure with a 5-ps symmetric pulse at the leading edge followed by a frequency-swept, rapidly oscillating trailing edge.
Abstract: We have transmitted a low-power beam of repetitive broadband THz pulses the record distance of 167 m through the atmosphere with 51% relative humidity at 21°C and have observed the broadened transmitted pulses with a signal to noise ratio greater than 200. The measured transmitted pulses reshaped from a 0.5-ps input pulse into an output pulse structure with a 5-ps symmetric pulse at the leading edge followed by a frequency-swept, rapidly oscillating trailing edge extending with increasing frequency to beyond 150 ps. The leading pulse appearing in the output pulse structure is composed of phase-locked frequency components extending from 0.07 to 0.37 THz that experienced negligible attenuation and group velocity dispersion due to transmission through water vapor. Such a stable pulse shape is suitable for the THz bit in a digital THz communications channel. Our results demonstrate a bit rate-distance product of greater than 8 (Gb/s)-km, which is comparable to an optical fiber digital communications channel.
TL;DR: The generation of few-cycle multiterawatt light pulses with a temporal contrast of 10(10), when measured as close as 2 ps to the pulse's peak, renders the system a promising front-end architecture for future multipetawatt laser facilities.
Abstract: We report the generation of few-cycle multiterawatt light pulses with a temporal contrast of 10(10), when measured as close as 2 ps to the pulse's peak. Tens of picoseconds before the main pulse, the contrast value is expected to spread much beyond the measurement limit. Separate measurements of contrast improvement factors at different stages of the laser system indicate that real contrast values may reach 10(19) and 10(14), when measured 50 and 25 ps before the pulse's peak, respectively. The combination of the shortest pulse duration and the highest contrast renders our system a promising front-end architecture for future multipetawatt laser facilities.
TL;DR: A fiber CPA system consisting of two coherently combined fiber amplifiers, which have been arranged in an actively stabilized Mach-Zehnder interferometer, and achieved at an average power of 30 W is presented.
Abstract: We present a fiber CPA system consisting of two coherently combined fiber amplifiers, which have been arranged in an actively stabilized Mach-Zehnder interferometer. Pulse durations as short as 470 fs and pulse energies of 3 mJ, corresponding to 5.4 GW of peak power, have been achieved at an average power of 30 W.
TL;DR: A passively mode-locked femtosecond fiber oscillator using only fiber-based components without intracavity dispersion compensation is reported on and the influence of pulse energy variation is discussed.
Abstract: We report on a passively mode-locked femtosecond fiber oscillator using only fiber-based components without intracavity dispersion compensation. The all-normal dispersion fiber laser operates in the dissipative-soliton regime and utilizes a spectral filter for pulse shaping. The 3.8 ps long pulses with pulse energies of 3.6 nJ can be dechirped with a grating compressor to 76 fs. The output spectrum reveals a full width at half maximum of 39.7 nm and a center wavelength of 1032 nm. The repetition rate is 71 MHz. The influence of pulse energy variation is discussed.
TL;DR: This work reports on the generation of high-average-power and high-peak-power ultrashort pulses from a mode-locked fiber laser operating in the all-normal-dispersion regime, using a large-mode-area ytterbium-doped large-pitch photonic-crystal fiber.
Abstract: We report on the generation of high-average-power and high-peak-power ultrashort pulses from a mode-locked fiber laser operating in the all-normal-dispersion regime. As gain medium, a large-mode-area ytterbium-doped large-pitch photonic-crystal fiber is used. The self-starting fiber laser delivers 27 W of average power at 50.57 MHz repetition rate, resulting in 534 nJ of pulse energy. The laser produces positively chirped 2 ps output pulses, which are compressed down to sub-100 fs, leading to pulse peak powers as high as 3.2 MW.
TL;DR: In this article, a chiral pulse train was proposed to achieve selectivity and directionality of laser-induced rotational excitation by using the chirality of a train, expressed through the period and direction of its polarization rotation.
Abstract: Trains of ultrashort laser pulses separated by the time of rotational revival (typically, tens of picoseconds) have been exploited for creating ensembles of aligned molecules. In this work we introduce a chiral pulse train---a sequence of linearly polarized pulses with the polarization direction rotating from pulse to pulse by a controllable angle. The chirality of such a train, expressed through the period and direction of its polarization rotation, is used as a new control parameter for achieving selectivity and directionality of laser-induced rotational excitation. The method employs chiral trains with a large number of pulses separated on the time scale much shorter than the rotational revival (a few hundred femtosecond), enabling the use of conventional pulse shapers.
TL;DR: In this article, a new kind of ultra-broadband high-energy dissipative soliton pulse was observed in a compact erbium-doped all-fiber laser with long cavity length and large net normal dispersion.
Abstract: We have experimentally observed a new kind of ultra-broadband high-energy dissipative soliton pulse in a compact erbium-doped all-fiber laser with long cavity length and large net normal dispersion. The pulse characteristics and evolution processes are quite distinct from those reported in previous literatures. Remarkablely, the spectral width of pulses increases whereas the pulse duration decreases with the increase of pump power, so the pulse energy and peak power increase monotonically. At the maximum available pump power of 1.1 W, this fiber laser delivers pulses with the 3-dB bandwidth of about 73 nm, the pulse duration of about 56 ps, the pulse energy of about 200 nJ, and the peak power of about 3.5 kW. The proposed all-fiber laser can find important potentials in high-energy pulse generation and amplification systems.
TL;DR: In this paper, the suitability of Hollow-Core Photonic Crystal Fibers (HC-PCF) for multi-watt average power pulse compression was demonstrated. But the authors only used a single cell core defect fiber and achieved peak powers of 1.6 MW and 1.7 MW.
Abstract: In this study we demonstrate the suitability of Hollow-Core Photonic Crystal Fibers (HC-PCF) for multiwatt average power pulse compression. We spectrally broadened picosecond pulses from a SESAM mode-locked thin disk laser in a xenon gas filled Kagome-type HC-PCF and compressed these pulses to below 250 fs with a hypocycloid-core fiber and 470 fs with a single cell core defect fiber. The compressed average output power of 7.2 W and 10.2 W at a pulse repetition rate of approximately 10 MHz corresponds to pulse energies of 0.7 µJ and 1 µJ and to peak powers of 1.6 MW and 1.7 MW, respectively. Further optimization of the fiber parameters should enable pulse compression to below 50 fs duration at substantially higher pulse energies.
TL;DR: In this article, the spectral and temporal output optical fields from a linear traveling-wave medium whose refractive index changes during its propagation within the medium were analyzed and it was shown that AWC alters the pulse power, pulse chirp, and pulse delay.
Abstract: We present universal formulas for the spectral and temporal output optical fields from a linear traveling-wave medium whose refractive index changes during its propagation within the medium. These formulas agree with known changes in central wavelength and energy that are associated with adiabatic wavelength conversion (AWC). Moreover, they reveal new changes to the optical pulses that have not been noticed, such as pulse compression and spectral broadening. Most significantly, we find that AWC alters the pulse power, pulse chirp, and pulse delay. All of these effects depend on whether the central wavelength is blueshifted or redshifted, the first sign of asymmetry to be reported for AWC. These findings impact the applications of AWC to optical signal processing in microphotonic and nanophotonic structures as well as in lightwave systems.
TL;DR: It is demonstrated how the resonant response of the femtosecond enhancement cavity can itself be used as a sensitive probe of optical nonlinearities at high intensities as a constraint on the strength of the nonlinear interaction that can be sustained in such optical cavities.
Abstract: We experimentally and numerically investigate the intracavity ionization of a dilute gas target by an ultrashort pulse inside a femtosecond enhancement cavity. Numerical simulations detail how the dynamic ionization of the gas target limits the achievable peak intensity of the evolving intracavity pulse beyond that of linear cavity losses, setting a constraint on the strength of the nonlinear interaction that can be sustained in such optical cavities. Experimental measurements combined with numerical simulations predict ionization levels in a femtosecond enhancement cavity for the first time. We demonstrate how the resonant response of the femtosecond enhancement cavity can itself be used as a sensitive probe of optical nonlinearities at high intensities.
TL;DR: The pulse lengths of intense few-cycle (4-10 fs) laser pulses at 790 nm are determined in real-time using a stereographic above-threshold ionization (ATI) measurement of Xe, i.e. the same apparatus recently shown to provide a precise, real- time, every-single-shot, carrier-envelope phase measurement of ultrashort laser pulses.
Abstract: The pulse lengths of intense few-cycle (4-10 fs) laser pulses at 790 nm are determined in real-time using a stereographic above-threshold ionization (ATI) measurement of Xe, i.e. the same apparatus recently shown to provide a precise, real-time, every-single-shot, carrier-envelope phase measurement of ultrashort laser pulses. The pulse length is calibrated using spectral-phase interferometry for direct electric-field reconstruction (SPIDER) and roughly agrees with calculations done using quantitative rescattering theory (QRS). This stereo-ATI technique provides the information necessary to characterize the waveform of every pulse in a kHz pulse train, within the Gaussian pulse approximation, and relies upon no theoretical assumptions. Moreover, the real-time display is a highly effective tool for tuning and monitoring ultrashort pulse characteristics.
TL;DR: A strong influence of different pulse durations and double pulse delay times on the formation of periodic surface structures on polyimide were observed employing ultrashort laser pulses tailored on a sub-picosecond and picosecond time scale.
Abstract: A strong influence of different pulse durations and double pulse delay times on the formation of periodic surface structures on polyimide were observed employing ultrashort laser pulses tailored on a sub-picosecond and picosecond time scale. Multi-photon, defect-related excitation mechanisms and thermal expansion of the polymer lattice correlated to a loss of long range order and polarisation memory were considered.
TL;DR: In this paper, a passively mode-locked fiber ring laser is demonstrated using a 49 cm long bismuth oxide based erbium-doped fiber (Bi-EDF) and a fast semiconductor saturable absorber.
Abstract: A passively mode-locked fiber ring laser is demonstrated using a 49 cm long bismuth oxide based erbium-doped fiber (Bi-EDF) and a fast semiconductor saturable absorber. Stable and clean short pulses are achieved because of these short and high nonlinear characteristics of the Bi-EDF. The laser operates at 1560 nm with a repetition rate of 8.3 MHz and a center wavelength of 1560 nm. The calibrated auto-correlator pulse trace of the laser shows a sech2 pulse shape, with an estimated pulse width of 340 fs.
TL;DR: In this article, the response of a harmonically confined mirror to an optical pulse in cavity optomechanics was investigated and it was shown that when the pulsed coupling strength takes the form of a chirped pulse, thermal fluctuations of the mirror can significantly transferred to the cavity field.
Abstract: We investigate the response of a harmonically confined mirror to an optical pulse in cavity optomechanics. We show that when the pulsed coupling strength takes the form of a chirped pulse, thermal fluctuations of the mirror can be significantly transferred to the cavity field. In addition, the frequency modulation of the pulse could enable a better cooling performance by suppressing the sensitivity of the dependence of detuning and pulse areas. Using numerical investigations, we find that the pulsed cooling is mainly limited by the cavity-field decay rate.
TL;DR: In this article, the authors revisited the third harmonic generation from femtosecond laser filament in air and its significant enhancement with a intercepting pump pulse, which has been reported very recently.
TL;DR: An experimental and theoretical study of the temporal properties of attosecond pulse trains in this regime is presented and the recorded harmonic spectra show distinct fine structures which can be explained by a varying temporal pulse spacing that can be controlled by the laser contrast.
Abstract: When a laser pulse hits a solid surface with relativistic intensities, XUV attosecond pulses are generated in the reflected light We present an experimental and theoretical study of the temporal properties of attosecond pulse trains in this regime The recorded harmonic spectra show distinct fine structures which can be explained by a varying temporal pulse spacing that can be controlled by the laser contrast The pulse spacing is directly related to the cycle-averaged motion of the reflecting surface Thus the harmonic spectrum contains information on the relativistic plasma dynamics