Showing papers on "Femtosecond pulse shaping published in 1994"
TL;DR: A new pulse-shaping technique, using an acousto-optic modulator as a spatial modulator in a zero-dispersion delay line that simplifies optical alignment and dramatically improves update rates.
Abstract: We demonstrate a new pulse-shaping technique, using an acousto-optic modulator as a spatial modulator in a zero-dispersion delay line. Compared with existing techniques, this approach simplifies optical alignment and dramatically improves update rates. It should also improve flexibility for generating complex waveforms.
277 citations
TL;DR: In this paper, the basic physical mechanisms governing pulse formation and the requirements for optimum performance of these novel ultrashort pulse laser sources are discussed and a family of solid-state laser oscillators with comparable performance can be developed.
Abstract: The exploitation of soliton-like pulse shaping mechanisms and the optimization of phase dispersion in broadband self-modelocked solid state laser oscillators have led to unprecedented advances in ultrafast laser technology. This paper reviews the basic physical mechanisms governing pulse formation and addresses the requirements for optimum performance of these novel ultrashort pulse laser sources. These considerations together with the demonstration of /spl ap/10 fs pulse generation from a Ti:sapphire laser suggest that a family of solid-state laser oscillators with comparable performance can be developed. >
227 citations
TL;DR: By operating near the zero second- and third-order dispersion point in a self-mode-locked Ti:sapphire laser the authors can generate sub-10-fs pulses and demonstrate that the pulse is shortest near the middle of the laser crystal, in one direction of propagation.
Abstract: We demonstrate that by operating near the zero second- and third-order dispersion point in a self-mode-locked Ti:sapphire laser we can generate sub-10-fs pulses. Our numerical simulations show that the pulse duration is limited by fourth-order dispersion and that shorter pulses will be possible if this can be reduced. Also, by inserting a pellicle in various positions in a Ti:sapphire cavity, we have measured the intracavity pulse duration and chirp of the circulating pulse in the laser. Our results demonstrate that the pulse is shortest near the middle of the laser crystal, in one direction of propagation. In the other direction of propagation, the pulse is positively chirped and several times longer.
214 citations
TL;DR: In this article, the dynamics of coherent phonon generation by femtosecond optical pulses in thin gold and silver films was studied using a pump and probe scheme, which was achieved by monitoring ultrafast surface vibrations in real time using laser-beam deflection.
Abstract: The dynamics of coherent phonon generation by femtosecond optical pulses in thin gold and silver films is studied using a pump and probe scheme. Detection is achieved by monitoring ultrafast surface vibrations in real time using laser-beam deflection. The phonon strain pulse shapes can be explained through the nonequilibrium coupling of the electron and phonon distributions, suggesting a new method for measuring the electron-phonon coupling constant.
203 citations
TL;DR: It is shown that even moderate self-phase modulation can significantly distort the recompressed pulse after amplification, thereby reducing the peak power and degrading the pulse contrast.
Abstract: The effect of self-phase modulation in chirped-pulse amplification is investigated. A numerical model is used to predict the effects of phase modulation on pulse recompression, and experimental results are presented that agree well with the calculations. We show that even moderate self-phase modulation can significantly distort the recompressed pulse after amplification, thereby reducing the peak power and degrading the pulse contrast.
155 citations
TL;DR: In this paper, a temporal hologram of a short optical pulse with a continuous-wave diode laser is read out and the shape information is converted into a spatial pattern that can be viewed with a camera.
Abstract: We report time-to-space mapping of femtosecond light pulses in a temporal holography setup. By reading out a temporal hologram of a short optical pulse with a continuous-wave diode laser, we accurately convert temporal pulse-shape information into a spatial pattern that can be viewed with a camera. We demonstrate real-time acquisition of electric-field autocorrelation and cross correlation of femtosecond pulses with this technique.
132 citations
Patent•
24 Aug 1994
TL;DR: Chirped Bragg gratings are used both for stretching and compressing of ultrashort optical pulses in a chirped pulse amplification system, so that even femtosecond pulses can be stretched and recompressed back to their initial shape and duration.
Abstract: Chirped Bragg gratings are used both for stretching and compressing of ultrashort optical pulses in a chirped pulse amplification system, so that even femtosecond pulses can be stretched and recompressed back to their initial shape and duration When used in chirped pulse amplification systems instead of bulk diffraction grating stretchers and compressors, Bragg gratings offer unprecedented compactness, robustness and system efficiency
127 citations
TL;DR: The pulse envelope for 1.54-THz pulses was in good agreement with a calculation from the Fourier transformation of the optical spectrum, indicating that the output pulses are transform limited.
Abstract: We report what is to our knowledge the first demonstration of terahertz-rate optical pulse generation by harmonic passive mode locking in a distributed-Bragg-reflector laser diode. Along with the fundamental repetition rate of 38.8 GHz, we observed 400-GHz, 800-GHz, and 1.54-THz harmonics, depending on the bias condition of gain section. The pulse envelope for 1.54-THz pulses was in good agreement with a calculation from the Fourier transformation of the optical spectrum, indicating that the output pulses are transform limited.
108 citations
TL;DR: An all-solid-state hybrid mode-locking technique for flash-lamp-pumped solid-state lasers that allows pulses with peak powers of >4 MW at a 10-Hz repetition rate directly from a single laser.
Abstract: We demonstrate an all-solid-state hybrid mode-locking technique for flash-lamp-pumped solid-state lasers. The combination of active acousto-optic modulation and fast saturable-absorber action from a low-temperature multiple quantum well allows strong pulse shaping to be achieved during the rapid pulse energy buildup from the flash-lamp pumping. Pulse durations as short as 4.5 ps have been generated. The high-energy storage available from Ti:Al2O3 allows this new mode-locking technique to produce pulses with peak powers of >4 MW at a 10-Hz repetition rate directly from a single laser.
84 citations
TL;DR: Using frequency-resolved optical gating, a 310-fs, 308-nm pulse is measured, whose phase is approximately cubic in time, and it is shown that this phase distortion probably results from self-phase modulation and amplifier detuning.
Abstract: We extend to the ultraviolet frequency-resolved optical gating a new method for measuring the intensity and phase evolution of an individual ultrashort pulse without assumption. Using frequency-resolved optical gating, we measure a 310-fs, 308-nm pulse, whose phase is approximately cubic in time. We show that this phase distortion probably results from self-phase modulation and amplifier detuning.
82 citations
TL;DR: It is shown that the concept of generalized pulses can be extended to multilevel systems, and shows that the excitation mechanism is universal.
Abstract: We show that the concept of \ensuremath{\pi} pulses can be extended to multilevel systems. Generalized \ensuremath{\pi} pulses selectively excite a target state via a mechanism that is closely related to the familiar excitation dynamics in a two-level system. The corresponding generalized area theorem does not refer to the ``area under the pulse envelope,'' but to an integral over a difference of instantaneous quasienergies. Nevertheless, there are the same possibilities of pulse shaping for the generalized pulses as for their two-level counterparts. A semiclassical interpretation of the resonance condition leads to an analytical approximation to the relevant quasienergies, and shows that the excitation mechanism is universal.
TL;DR: In this paper, the authors theoretically and experimentally clarified the limit of incident optical pulse power in coherent optical time-domain reflectometry (C-OTDR) enhanced with optical fiber amplifiers.
Abstract: This paper theoretically and experimentally clarifies the limit of incident optical pulse power in coherent optical time-domain reflectometry (C-OTDR) enhanced with optical fiber amplifiers. The critical pulse power, at which the performance of C-OTDR is degraded by the effect of optical nonlinear phenomena in a single-mode optical fiber, depends on the amplified optical pulse waveform and the pulse width. For a pulse width of 1 /spl mu/s or longer, the incident pulse power is limited by the effect of self-phase modulation (SPM). When an optical pulse having a power gradient within the pulse width is incident to a single-mode optical fiber, the optical frequency of the backscattered signal is shifted by SPM, and the center frequency of the signal moves outside the receiver band, so the sensitivity of C-OTDR is degraded. For a pulse width of 100 ns, the incident optical pulse power is limited by four-wave mixing (FWM) which transfers the energy from the incident optical pulse to Stokes and anti-Stokes light as a result of the interaction between the incident optical pulse and amplified spontaneous emission. This paper also demonstrates the high performance of C-OTDR enhanced with EDF A's with 48, 44, 39, and 29 dB single-way dynamic ranges for pulse widths of 10 /spl mu/s, 4 /spl mu/s, 1 /spl mu/s, and 100 ns, respectively, limited by the effect of SPM or FWM. These results are believed to be the best performance of C-OTDR with EDFA's. >
TL;DR: In this article, a two-dimensional calculation of the propagation of an ultrashort laser pulse through an ionising gas is presented, and the correlation between spatial and spectral effects is investigated.
TL;DR: Self-stabilization and self-organization of the output pulse train at repetition rates from the fundamental cavity frequency of 700 kHz up to 440 MHz and report on polarization effects.
Abstract: We report what is to our knowledge the first femtosecond pulse generation at 1.3 μm in a Pr3+-doped fluoride fiber laser. After optimization of the cavity length and dispersion, the laser generated pulses as short as 620 fs. We also describe self-stabilization and self-organization of the output pulse train at repetition rates from the fundamental cavity frequency of 700 kHz up to 440 MHz and report on polarization effects.
Proceedings Article•
08 May 1994TL;DR: In this paper, the authors present a method for the measurement of the complex electric field of ultrashort light pulses, which is easy to implement experimentally and very reliable even in the case of noisy data.
Abstract: The measurement of the complex electric field of ultrashort light pulses is highly desirable to obtain complete information on their amplitude and phase. The common means of intensity autocorrelations and spectral measurements do not provide any information on the spectral phase of the measured pulse. A host of methods have been devised to overcome this problem but none of them has thus far proven to be convenient enough to be widely adopted. We present here a method1,2 which is easy to implement experimentally and very reliable even in the case of noisy data.
TL;DR: In this article, a systematic study of the dc-electric-field dependence of THz radiation from a bulk GaAs sample optically excited by femtosecond pulses is presented.
Abstract: We report a systematic study of the dc-electric-field dependence of THz radiation from a bulk GaAs sample optically excited by femtosecond pulses. The experimental results reveal that both displacement and transport currents contribute to THz radiation and the relative contributions are shown to be very sensitive to the dc electric field. This observation agrees qualitatively with a simulation based on a fully quantum-mechanical treatment of the transient photoconductive response of GaAs.
TL;DR: Chirped pulse amplification of a stretched pulse passively mode-locked erbium fiber laser is demonstrated in this article, where the two-stage all-fiber amplifier system delivers 800fs pulses with pulse energies up to 100 nJ at a repetition rate of 200 kHz.
Abstract: Chirped pulse amplification of a stretched pulse passively mode‐locked erbium fiber laser is demonstrated The two‐stage all‐fiber amplifier system delivers 800‐fs pulses with pulse energies up to 100 nJ at a repetition rate of 200 kHz
TL;DR: In this article, the authors describe femtosecond high power optical pulses using hybrid passive-active mode-locking techniques, where angle stripe geometry GaAs/AlGaAs semiconductor laser amplifiers are employed in an external cavity including prisms and a stagger-tuned quantum-well saturable absorber.
Abstract: We describe the generation of femtosecond high power optical pulses using hybrid passive-active mode-locking techniques. Angle stripe geometry GaAs/AlGaAs semiconductor laser amplifiers are employed in an external cavity including prisms and a stagger-tuned quantum-well saturable absorber. An identical amplifier also serves as an optical power amplifier in a stretched pulse amplification and recompression sequence. After amplification and pulse compression this laser system produces 200 fs, 160 W peak power pulses. We discuss and extend our theory, and supporting phenomenological models, of picosecond and subpicosecond optical pulse amplification in semiconductor laser amplifiers which has been successful in calculating measured spectra and time-resolved dynamics in our amplifiers. We have refined the theory to include a phenomenological model of spectral hole-burning for finite intraband thermalization time. Our calculations are consistent with an intra-band time of approximately 60 fs. This theory of large signal subpicosecond pulse amplification will be an essential tool for understanding the mode-locking dynamics of semiconductor lasers and for analysis of high speed multiple wave-length optical signal processing and transmission devices and systems based on semiconductor laser amplifiers.
TL;DR: It is demonstrated that intracavity filtering and soliton formation in actively mode-locked lasers can lead to pulse shortening by as much as a factor of 30.
Abstract: We demonstrate that intracavity filtering and soliton formation in actively mode-locked lasers can lead to pulse shortening by as much as a factor of 30. Pulses as short as 310 fs have been generated from a Nd:glass laser that is mode locked only by an acousto-optic modulator.
TL;DR: In this paper, a model for simulation of laser pulses over extended distances (multiple diffraction lengths) in an underdense plasma is described, and a model is used to simulate radius-tailored laser pulses, which can propagate over such distances with minimal distortion in a uniform plasma.
Abstract: A Maxwell‐fluid model is described, which allows simulation of laser pulses over extended distances (multiple diffraction lengths) in an underdense plasma This model is used to simulate radius‐tailored laser pulses, which can propagate over such distances with minimal distortion in a uniform plasma Theoretical model equations governing the choice of radius tailoring are also given A radius‐tailored pulse has constant power approximately equal to the critical power for relativistic guiding over the length of the pulse and a spot size at focus that varies over the length of the pulse A laser pulse configuration of this type can be constructed from a series of ultrashort Gaussian pulses
TL;DR: Chirped pulse amplification (CPA) and recompression have been used in a large aperture KrF laser system with a power focused onto target in a 300 fs pulse reached 1 TW with an irradiance of ≈ 10 19 W/cm 2 as mentioned in this paper.
TL;DR: In this article, a flash-lamp-pumped Cr:LiSrAlF6 (Cr:LiSAF) laser system capable of producing femtosecond pulses exhibiting peak powers greater than 2 TW was developed.
Abstract: We have developed a compact, flash-lamp-pumped Cr:LiSrAlF6 (Cr:LiSAF) laser system capable of producing femtosecond pulses exhibiting peak powers greater than 2 TW. Chirped pulse amplification in a Cr:LiSAF regenerative amplifier produces 15-mJ pulses at a 5-Hz repetition rate. Further amplification in Cr:LiSAF yields recompressed pulse energies of 280 mJ and a pulse duration of less than 135 fs at a 1.0-Hz repetition rate. We describe the design and performance of this laser as well as the optimization of chirped pulse amplification in flash-lamp-pumped Cr:LiSAF.
TL;DR: In this article, simple analytic expressions are derived that describe the propagation of a Gaussian high-power laser pulse subject to ionization defocusing in a gas, based on the paraxial-ray equation and the Coulomb-barrier model.
Abstract: Simple analytic expressions are derived that describe the propagation of a Gaussian high-power laser pulse subject to ionization defocusing in a gas. The analysis is based on the paraxial-ray equation and the Coulomb-barrier model for optical field ionization. Good agreement with recent experimental data is obtained without an adjustable parameter. Experimental observations relevant to high-power pulse propagation follow naturally from the theory.
TL;DR: In this article, the output of a mode-locked Nd:YLF laser is used as seed and a synchronized Ti:sapphire laser serves as pump to generate high-repetition rate femtosecond pulses with an energy of 10 pJ per pulse.
TL;DR: In this paper, a technique for eliminating prepulse emission from a chirped-pulse amplification Nd:glass laser, a nonlinear optical technique based on optical parametric amplification, was proposed.
Abstract: We introduce a new technique for eliminating prepulse emission from a chirped-pulse amplification Nd:glass laser, a nonlinear optical technique based on optical parametric amplification. We demonstrate not only that the intensity-contrast ratio of the laser pulse can be enhanced from R to ~R3 but also that significant pulse shortening can occur under appropriate conditions with this technique.
TL;DR: In this paper, the femtosecond radiation from a 1 kHz repetition rate Ti:sapphire regenerative amplifier to the near infrared (1.2 −1.5 μm), visible (554 −593 nm), and for the first time to the vacuum ultraviolet spectral region well below 190 nm.
Abstract: The article presents single step and cascade methods for converting the femtosecond radiation from a 1 kHz repetition rate Ti:sapphire regenerative amplifier to the near‐infrared (1.2–1.5 μm and 1.6–2.2 μm), visible (554–593 nm), and for the first time to our knowledge to the vacuum ultraviolet spectral region well below 190 nm. Using only solid state materials (nonlinear optical crystals) femtosecond pulses are generated through phase‐matched mixing processes down to 172.7 nm. The developed scheme for femtosecond parametric conversion provides nearly bandwidth limited femtosecond pulses, whose duration is comparable or even shorter than that of the pump pulses. The temporal gain narrowing in the optical parametric amplifier is identified as a pulse compression mechanism on the femtosecond time scale leading to generation of infrared light pulses as short as ≊50 fs. As a whole our all‐solid state laser complex provides independently tunable and synchronized sub‐200 fs light pulses simultaneously at severa...
TL;DR: In this article, multiple colliding pulse mode-locked operation where 3 or 4 ultrashort pulses are present simultaneously within a semiconductor laser is described, and frequency and time domain measurements show that a multisectioned laser can be switched between two, three, and four pulse operation.
Abstract: Multiple colliding pulse mode‐locked operation where 3 or 4 ultrashort pulses are present simultaneously within a semiconductor laser is described. Frequency and time domain measurements show that a multisectioned laser can be switched between two, three, and four pulse operation. In four pulse operation, pulse widths of approximately 1.3 ps at repetition rates of 240 GHz have been observed from a 600‐μm‐long laser.
TL;DR: In this paper, a transient three-dimensional model is used in a numerical investigation of the spatiotemporal and spectral characteristics of a femtosecond pulse of 1014-1016 W cm-2 intensity propagating in rare gases.
Abstract: A transient three-dimensional model is used in a numerical investigation of the spatiotemporal and spectral characteristics of a femtosecond pulse of 1014—1016 W cm-2 intensity propagating in rare gases. It is shown that nonlinear defocusing caused by the ionisation of a gas may result in a 20-fold reduction of the peak intensity in the beam waist. The transverse distribution of the intensity beyond the waist is a ring with a minimum on the beam axis at a pressure of 1 bar and with a local maximum on the axis at 5 bar. The frequency spectra of such a pulse are in quantitative agreement with experimental data.
TL;DR: In this paper, the authors achieved stable amplification of femtosecond pulses to the millijoule level with pulse-to-pulse energy fluctuations below those of the pump source.
Abstract: We have achieved highly stable amplification of femtosecond pulses to the millijoule level with pulse-to-pulse energy fluctuations below those of the pump source. Our Ti:Al2O3 amplifier produces pulses with a root-mean-square fluctuation in pulse energy of 0.42%, which is the lowest value to our knowledge for any optical pulse amplifier reported to date. Pump-noise suppression by a factor of 40 is demonstrated for the first time to our knowledge. We discuss this high-stability behavior through model simulations.
TL;DR: Using the stimulated Brillouin scattering phase conjugation and pulse compression technique, a conventional long pulse ruby laser was successfully converted to give 300 ps pulses at 1 J energy level as discussed by the authors.
Abstract: Using the stimulated Brillouin scattering phase conjugation and pulse compression technique, a conventional long pulse ruby laser was successfully converted to give 300 ps pulses at 1 J energy level. The technique allows the use of smaller amplifiers than required in a conventional short pulse laser which in turn leads to operation at increased repetition rate. The completed laser when operated at 1.5 Hz produces stable output parameters. Each laser pulse is characterized by a sharp rise and a measured pre‐pulse level of less than 10−6 of the main pulse, making it suitable for LIDAR Thomson scattering measurements.