Showing papers on "Femtosecond pulse shaping published in 1990"
TL;DR: This work reports programmable shaping of femtosecond optical pulses by use of a multielement liquid-crystal modulator to manipulate the phases of spatially dispersed optical frequency components.
Abstract: We report programmable shaping of femtosecond optical pulses by use of a multielement liquid-crystal modulator to manipulate the phases of spatially dispersed optical frequency components. Our approach provides for continuously variable control of the optical phase and permits the pulse shape to be reconfigured on a millisecond time scale. We use the apparatus to demonstrate femtosecond pulse-position modulation as well as programmable compression of chirped femtosecond pulses.
378 citations
TL;DR: In this article, a high-resolution Michelson interferometer for stable phase-locked ultrashort pulse pair generation is proposed, and the effects of phaselocked pulse pairs on nuclear motion in the electronic ground state are investigated.
Abstract: Articles you may be interested in Development of high resolution Michelson interferometer for stable phase-locked ultrashort pulse pair generation Rev. Impulsive effects of phaselocked pulse pairs on nuclear motion in the electronic ground state Fluorescencedetected wave packet interferometry: Time resolved molecular spectroscopy with sequences of femtosecond phaselocked pulses
193 citations
TL;DR: A simple linear filtering technique for transforming individual femTosecond light pulses into terahertzrepetition-rate bursts of femtosecond pulses achieves high efficiency and pulse repetition rates approaching 6 THz.
Abstract: We describe a simple linear filtering technique for transforming individual femtosecond light pulses into terahertzrepetition-rate bursts of femtosecond pulses. By using phase-only filtering, high efficiency is achieved. Pulse repetition rates approaching 6 THz are obtained.
130 citations
TL;DR: The results show that the method is most advantageous for incident pulses between 0.1- and 1.0-ps duration and microjoule and higher energies and that second harmonic pulse duration and conversion efficiency are not highly sensitive to optical misalignments of the order of 1 degrees.
Abstract: We theoretically analyze a method for matching group velocities of fundamental and second harmonic femtosecond pulses during phase matched frequncy doubling by predispersing the fundamental pulse with a prism. The method permits improved conversion efficiency by allowing crystal lengths of several millimeters without sacrificing second harmonic pulse duration. Second harmonic pulse energy and duration are analyzed for beta-BaB(2)O(4), and limiting experimental factors are discussed. The results show that the method is most advantageous for incident pulses between 0.1- and 1.0-ps duration and microjoule and higher energies and that second harmonic pulse duration and conversion efficiency are not highly sensitive to optical misalignments of the order of 1 degrees .
75 citations
TL;DR: Pulses shorter than 500 fs were generated by pulse compression modelocking of a neodymium fiber laser in this article, where an analysis of the pulse forming process was presented, and higher-order nonlinear effects were observed.
Abstract: Pulses shorter than 500 fs were generated by pulse compression modelocking of a neodymium fibre laser. An analysis of the pulse forming process is presented. Higher-order nonlinear effects were observed.
42 citations
TL;DR: In this paper, the gain saturation characteristics of traveling-wave semiconductor laser amplifiers (TWAs) were theoretically and experimentally investigated, and the pulse energy gain saturation was experimentally confirmed to be independent of pulse durations and to be determined only by pulse energy.
Abstract: The gain saturation characteristics of traveling-wave semiconductor laser amplifiers (TWAs) are theoretically and experimentally investigated. In the amplification of an isolated pulse whose repetition period is short compared to the carrier lifetime, the gain saturation is related through the carrier lifetime to the gain saturation in CW amplification. When the output pulse energy is smaller than the saturation energy, short optical pulses can be amplified without pulse shape distortion, whereas high-energy pulses suffer from pulse shape distortion due to the temporal gain variation during the pulse radiation. FWHM pulse duration variation in amplification by TWAs depends on the input pulse shape. The pulse energy gain saturation was experimentally confirmed to be independent of pulse durations and to be determined only by the pulse energy. In extremely-high-repetition-rate pulse amplification, the saturation of the pulse energy gain is determined by the average signal power. >
31 citations
IBM1
TL;DR: This is the first observation, to the author's knowledge, of intrafiber pulse compression for normal group-velocity dispersion, and a compressed pulse width of 0.3 psec for a 2-psec input pulse is observed.
Abstract: Detailed subpicosecond observations of the time dependence of a propagating cross-phase-modulated pulse are presented. It is observed that propagation of a weak visible pulse in one polarization mode of a birefringent optical fiber, so that it is cross-phase modulated by the edge of a strong pulse in the other mode, can result in significant compression of the weak pulse, for normal dispersion, without external compensation. The compression efficiency is found to be enhanced by utilizing the group-velocity mismatch between the two modes to synchronize the weak pulse with the broadening edge of the strong pulse. This is the first observation, to the author’s knowledge, of intrafiber pulse compression for normal group-velocity dispersion, and a compressed pulse width of 0.3 psec for a 2-psec input pulse is observed.
27 citations
27 citations
TL;DR: Degenerate cross-phase modulation can be applied to femtosecond optical pulse compression and amplification without the use of gratings or prisms and to signal processing owing to the small walk-off and the degenerate four-wave mixing between the pump and probe pulses.
Abstract: Temporal and spectral profiles of a linearly polarized ultrashort laser pulse modulated by a copropagating perpendicularly polarized strong laser pulse with the same frequency in condensed matter have been modeled. Degenerate cross-phase modulation can be applied to femtosecond optical pulse compression and amplification without the use of gratings or prisms and to signal processing owing to the small walk-off and the degenerate four-wave mixing between the pump and probe pulses. In a double pump compression case, the pulse duration of the probe pulse has been reduced by a factor of 15 with the energy gain of over fourfold. This result gives a power gain of 60-fold.
25 citations
TL;DR: In this paper, a 1.48-mu m LD-pumped Er/sup 3+/-doped fiber laser amplifier was used to achieve a peak power of 12 W and 105 pJ for 9-ps pulses at a 33 GHz repetition frequency.
Abstract: Intense picosecond optical pulse generation from a gain-switched laser diode (LD) was demonstrated using a 1.48- mu m LD-pumped Er/sup 3+/-doped fiber laser amplifier. Saturation characteristics of the amplifier output power were also measured as a function of input repetition frequency. An amplified peak power of 12 W and 105-pJ pulse energy were obtained for 9-ps pulses at a 33-GHz repetition frequency. This is the highest peak power yet demonstrated in pulse generation employing all-laser diodes as active devices. >
24 citations
TL;DR: In this article, the compression of a femtosecond single-mode fiber with a phase-modulating pulse was evaluated and it was shown that the compression ratio can be improved to 6.8-fs by matching the group velocities.
Abstract: We report the practical evaluation of the compression in a dispersive single-mode fiber of a weak, femtosecond pulse by its interaction with a longer, intense, phase-modulating pulse. Our numerical analysis takes into account the group-velocity dispersion, unavoidable in real fibers, which affects the chirp linearity and hence the extent of compression attainable. We show that, even in the absence of matching of the pulse group velocities, a weak 50-fs pulse of any wavelength between 315 and 800 nm can be compressed from 18.5 to 6.8-fs by a 100-fs, 250-kW pulse at 630 nm. When the group velocities are matched, this compression is superior to that attainable by the less flexible, conventional self-phase modulation technique. In addition, it is shown that a weak, femtosecond near-infrared pulse propagating in the anomalous dispersion region can be compressed by fiber propagation alone, almost without being influenced by group velocity mismatching.
TL;DR: In this paper, an optical pulse-shaping technique using a Fourier-transformed hologram is presented, which permits arbitrary manipulation of the amplitude and phase of the input pulse.
Abstract: An optical pulse-shaping technique using a Fourier-transformed hologram is reported. This technique permits the arbitrary manipulation of the amplitude and phase of the input pulse. We demonstrate the shaping of a picosecond pulse into asymmetric multipulses and into a square pulse.
TL;DR: In this article, the pulse propagation and phase modulation of second-harmonic generation of ultrafast pulses in nonlinear-optical media have been modeled and analyzed based on experimental work.
Abstract: Pulse propagation and phase modulation of second-harmonic generation of ultrafast pulses in nonlinear-optical media have been modeled and analyzed based on experimental work. In order to describe the temporal pulse profile, both cross-phase-modulation and induced-absorption processes have been introduced. The pulse profiles of cross-phase-modulated second-harmonic pulses for non-phase-matched nonlinear media with short interaction length are shown to depend on group-velocity dispersion, absorption, and induced phase matching.
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20 Apr 1990TL;DR: In this article, the modulated optical pulse groups are applied to n cascade-connected pulse interval compressors one after another, in which they are brought close to each other two by two and then coupled together, thereby producing modulated optic pulse packets compressed as desired.
Abstract: In ultrashort optical pulse modulating equipment optical pulses emitted from a laser in synchronism with input electrical signals are modulated by the electrical signals, the modulated optical pulses are applied to a first-stage pulse interval compressor, in which they are alternately distributed, one by one, by an optical switch to two optical fiber delay lines, two modulated optical pulses delayed by the two optical fiber delay lines are brought close to each other, and modulated optical pulse groups, each composed of two closely spaced modulated optical pulses, are output from an optical coupler. Also in the next-stage pulse interval compressor the modulated optical pulse groups input thereinto are alternately distributed, one by one, by an optical switch to two optical fiber delay lines, in which predetermined delays are caused in the modulated optical pulse groups, respectively, and then they are coupled together by an optical coupler, thereby creating modulated optical pulse groups each composed of four modulated optical pulses. In this way, modulated optical pulse groups are applied to n cascade-connected pulse interval compressors one after another, in which they are brought close to each other two by two and then coupled together, thereby producing modulated optical pulse packets compressed as desired.
TL;DR: In this paper, the authors used the density-matrix method to analyze the creation of space-time coherences by the pump pulse and their effect on the probe pulse.
Abstract: In femtosecond laser‐pulse experiments the pump pulse, with duration comparable or shorter than a typical period of intra‐ or intermolecular vibrations, creates a nonstationary wave packet. In this paper we use the density‐matrix method to analyze creation of space–time coherences by the pump pulse and their effect on the probe pulse. Expressions for the density‐matrix jumps, induced by the probe pulse, have been obtained in a general case. The material equations, determining propagation of the probe pulse, have been derived.
TL;DR: In this article, a fiber Raman laser with intracavity pulse compression was investigated both theoretically and experimentally, and the dynamics of laser generation from the spontaneous noise level was investigated numerically and stable regimes of femtosecond pulse generation were found.
Abstract: A fiber Raman laser with intracavity pulse compression is investigated both theoretically and experimentally. A theoretical model of such a laser is described: the dynamics of laser generation from the spontaneous noise level is investigated numerically, and stable regimes of femtosecond pulse generation are found. Smoothly tuned generation inside two Stokes components with a minimum pulse width of ∼150 fsec is obtained experimentally. We show that these lasers can generate smoothly tuned pulses in all silica-fiber transparency spectral regions. The efficiency of pump energy conversion into the Raman generation energy can reach more than 80% (30% was obtained experimentally), and the average output power can be more than 1 W.
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02 May 1990TL;DR: In this article, the wavefront of an individual soliton pulse is steepened and a continuous dispersive non-linear propagation structure is constructed, which is called a pulse compressor for solitons.
Abstract: A pulse compressor for solitons includes a continuous dispersive non-linear propagation structure so constructed so that the wavefront of an individual soliton pulse is steepened. In addition, the pulse compressor has a continuously reduced time constant on a spatial, as opposed to a temporal basis. Various structures of the pulse compressor are described.
TL;DR: The propagation of femtosecond pulses in a colliding-pulse mode-locked dye laser near zero group-velocity dispersion is studied and the pulse spectrum is shown to exhibit a double-peak structure that can be explained by nonlinear pulse propagation near zero dispersion.
Abstract: The propagation of femtosecond pulses in a colliding-pulse mode-locked dye laser near zero group-velocity dispersion is studied. The pulse spectrum is shown to exhibit a double-peak structure. This structure and its dependence on the intracavity dispersion can be explained by nonlinear pulse propagation near zero dispersion. A value for the third-order dispersion of the laser cavity is deduced and is found to be predominant for pulses shorter than 50 fsec.
TL;DR: In this paper, a spatially dependent negative chirp develops, accompanied by a titled pulse front, when a pulse traverses a single dispersive element, and it is demonstrated experimentally that this plane can be imaged, preserving the compressed pulse duration in the plane of the image, and allowing a continuous change of the pulse front tilt through the variation of the magnification.
15 Oct 1990-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse.
Abstract: We have performed preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and have demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse. In a typical case, we project pulse compression by a factor of 13.3, from an initial pulse width of 3.13 ps to a final pulse width of 236 fs, at a wavelength of 3.35 μm and an electron energy chirp of +2% (energy increasing towards the back of the pulse). This represents an optical pulse less than half as short as the slippage length of 47 magnet periods for this wavelength.
Patent•
09 Jan 1990TL;DR: In this paper, a system for measuring the thermal characteristic of the surface-lattice of solid state materials with picosecond time resolution uses a picoscond laser pulse which is synchronized with a picosescond electron pulse; the electron pulse being generated by splitting the laser pulse into two beams one of which interacts with the surface under test and the second activating the cathode of an electron gun creating an electron pulse, collimated, focused and incident at a small acute angle (1-3 degrees) on the surface.
Abstract: A system for measuring the thermal characteristic of the surface-lattice of solid state materials with picosecond time resolution uses a picosecond laser pulse which is synchronized with a picosecond electron pulse; the electron pulse being generated by splitting the laser pulse into two beams one of which interacts with the surface under test and the second activates the cathode of an electron gun creating an electron pulse which is, collimated, focused and incident at a small acute angle (1-3 degrees) on the surface. The electron pulse generates a reflection high energy electron diffraction pattern (RHEED) which provides information on the surface temperature in accordance with the Debye-Waller effect. Time resolved measurements are made by using electron pulses which are delayed with respect to the laser pulses by successively greater time intervals.
Patent•
06 Jun 1990
TL;DR: In this article, a phase conjugate laser system was proposed to produce relatively square laser pulses derived from relatively Gaussian laser pulses, where a laser pulse is propagated through a plasma switch, and the pressure therein is adjusted to truncate the rear portion of the laser pulse.
Abstract: A system and method for producing relatively square laser pulses derived from relatively Gaussian laser pulses. The system comprises a phase conjugate laser system that comprises a laser oscillator, an amplifying medium and a phase conjugate mirror having a nonlinear confined at a predetermined pressure. The mirror is adapted to truncate the front portion of an applied laser pulse. A plasma switch is disposed between the laser oscillator and the amplifying medium that has a gas confined therein at a predetermined pressure. The plasma switch and phase conjugate mirror cooperate to truncate the laser pulse to produce a laser pulse having a relatively square shape. Controlling the pressures in the plasma switch and phase conjugate mirror provides a means of controlling the formation of square-shaped laser pulses. In addition, a delay line may be employed in the system that is controllable in length that assists in controlling the truncation of the pulse in the plasma switch. A method of forming a square laser pulse in accordance with the invention comprises the following steps. A laser pulse is propagated through a plasma switch, and the pressure therein is adjusted to truncate the rear portion of the laser pulse. The truncated laser pulse is then transmitted through a laser amplifier medium to amplify the laser pulse. The amplified laser pulse is then reflected from a phase conjugate mirror. The pressure in the phase conjugate mirror is adjusted to a predetermined pressure to truncate the front portion of the laser pulse, thus producing a relatively square output pulse. Additionally, the relative length of a delay line disposed in the optical path may also be adjusted to assist in truncating the rear portion of the laser pulse.
TL;DR: In this article, a detailed experimental investigation of the formation of ultrashort pulses in a CW-pumped passively mode-locked CPM dye laser is described, and it is found that it takes approximately 10/sup 4/round trips for the circulating energy in the cavity to reach the level at which the passive mode-locking process is initiated, and a subsequent approximately 10 /sup 3/rounds for the ultrashingort pulse evolution to reach a steady state.
Abstract: A detailed experimental investigation of the formation of ultrashort pulses in a CW-pumped passively mode-locked CPM dye laser is described. It is found that it takes approximately 10/sup 4/ round trips for the circulating energy in the cavity to reach the level at which the passive mode-locking process is initiated, and a subsequent approximately 10/sup 3/ round trips for the ultrashort pulse evolution to reach a steady state. Sequences of autocorrelation profiles and spectra are presented showing the dynamic pulse evolution, and the influence of intracavity group velocity dispersion on pulse formation is examined. >
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25 Sep 1990TL;DR: In this article, an optical pulse compressor having a single deflecting dispersive optical element in the form of a diffraction grating (10) or prism for temporal compression of an optical pulses, the frequency of which increases during the pulse duration, is presented.
Abstract: An optical pulse compressor having a single deflecting dispersive optical element in the form of a diffraction grating (10) or prism for temporal compression of an optical pulse, the frequency of which increases during the pulse duration. An elongated target (T) for receiving the compressed pulse is arranged in parallel with an output surface of the grating or prism. To increase the inclination of the pulse front for effective synchronous travelling wave excitation of the target the output surface of the diffraction grating or prism can be interfaced by an immersion medium or the beam path can be made to converge in the plane containing the target by a cylindrical lens or a reducing imaging optical system can be arranged between the grating or prism and the target.
TL;DR: In this article, the amplification and propagation of an initial Stokes seed pulse in a synchronously pumped fiber Raman laser configuration are formulated, and analytic solutions are derived, and simple expressions for the rate of pulse compression, the steady state pulse fluence, and the minimum steady-state pulse duration are obtained.
Abstract: Dynamical equations describing the amplification and propagation of an initial Stokes seed pulse in a synchronously pumped fiber Raman laser configuration are formulated, and analytic solutions are derived. A train of Stokes shifted pulses is produced. Their individual characteristics eventually evolve on successive round trips through the fiber into subpicosecond pulses having constant fluence and decreasing temporal duration. Raman pulse compression stops when it is counterbalanced by the effects of group velocity dispersion and phase modulation in the normal dispersion regime. Pulse breakup due to soliton formation can occur in the anomalous dispersion regime. Simple expressions for the rate of pulse compression, the steady-state pulse fluence, and the minimum steady-state pulse duration are obtained. >
01 Jan 1990
TL;DR: In this paper, a modified Fabry-Perot electrooptical modulator was proposed to convert cw light to sub-picosecond high peak optical pulses with near 100% energy conversion efficiency regardless of laser linewidth.
Abstract: A new ultrashort optical pulse generator, the “modified Fabry-Perot electrooptical modulator” is proposed. From theoretical analysis it is derived that this method makes it possible to convert cw light to subpicosecond high peak optical pulses with near 100% energy conversion efficiency regardless of laser linewidth.
TL;DR: In this article, the amplitude, phase, spectral, and time characteristics of laser radiation pulses are determined based on two spectra of an investigated radiation pulse: the original pulse and that transformed by a filter with characteristics that vary with time.
Abstract: An analysis is made of a method for determination of the amplitude, phase, spectral, and time characteristics of laser radiation pulses. The method is based on recording two spectra of an investigated radiation pulse: the original pulse and that transformed by a filter with characteristics that vary with time. An analysis of the resultant distributions of the intensity in these two spectra then yields the amplitude and phase spectra and the structure of a pulse.
01 Jan 1990
TL;DR: In this article, stable pulses were generated from a cw passively mode-locked Ti:Al2O3 laser with a prism-pair dispersion compensator inside the cavity.
Abstract: We have generated stable pulses less than 170 fs around 750 nm from a cw passively mode-locked Ti:Al2O3 laser with a prism-pair dispersion compensator inside the cavity. The pulse shaping mechanism mainly originates from the combined actions of self-phase modulation (SPM) and group velocity dispersion or soliton-like pulse formation.
TL;DR: In this article, the authors studied the self-start of passive mode-locking in a laser with a nonlinear mirror in the form of a fiber loop reflector and demonstrated that intracavity interferometric pulse compression in nonlinear resonator makes it possible to broaden the bandwidth and to accomplish efficient pulse shortening.
Abstract: Using a computer simulation, the authors have studied self-start of passive mode-locking in a laser with a nonlinear mirror in the form of a fiber loop reflector. They have demonstrated that intracavity interferometric pulse compression in a nonlinear resonator makes it possible to broaden the bandwidth and to accomplish efficient pulse shortening. Stable solutions have been found for perfect mode-locking with a steady-state pulse bandwidth which essentially exceeds the gain bandwidth. >
TL;DR: In this paper, a two-stage femtosecond pulse amplification scheme based on a pulse stretching-recompression procedure was proposed, achieving an energy conversion efficiency of 2% for the dye amplifier using pump pulses of 2 ns and a highly viscous solvent.