scispace - formally typeset
Search or ask a question

Showing papers on "Femtosecond pulse shaping published in 1975"


Journal ArticleDOI
TL;DR: In this article, a generalization of the classical molecular-optics theory of the optical Kerr effect (OKE) is presented which permits a study of the effect when induced by ultrashort laser pulses.
Abstract: A generalization of the classical molecular-optics theory of the optical Kerr effect (OKE) is presented which permits a study of the effect when induced by ultrashort laser pulses. Explicit relationships between results from this general theory and often-used phenomenological equations governing the temporal behavior of the OKE are established. Numerical results are presented for the liquids carbon disulfide and nitrobenzene, illustrating in detail the temporal nature and intensity of the birefringence induced in these liquids by ultrashort laser pulses. The importance of these results is discussed in connection with a number of self-induced nonlinear phenomena arising from the OKE as well as in conjunction with the OKE shutter switched by an ultrashort laser pulse. In addition, a discussion is given of the nature of the birefringence induced by picosecond laser pulses as well as aspects of the extension of OKE photography to the subpicosecond domain.

101 citations


Journal ArticleDOI
TL;DR: In this article, the evolution of the ultrashort pulse evolution for a large number of round-trips was investigated and a stationary pulse was found for a single round-trip.

37 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the problem of generating an optical pulse of arbitrary shape and phase may be reduced to producing an arbitrary spectral filter, and the extent to which any desired filter may be realized in practice was examined.
Abstract: It is shown that the problem of generating an optical pulse of arbitrary shape and phase may be reduced to the problem of producing an arbitrary spectral filter. This generalizes the short-pulse generation techniques, which are based on the laser breakdown switch, as the active element. We examine the extent to which any desired filter may be realized in practice, and some examples are given.

18 citations


Book
01 Jan 1975
TL;DR: High-speed pulse techniques as discussed by the authors, High speed pulse techniques, high speed pulse technique, HSPP techniques, High-speed Pulses, High speed pulses, high-speed pulses.
Abstract: High-speed pulse techniques , High-speed pulse techniques , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

16 citations


Journal ArticleDOI
TL;DR: In this article, a picosecond-gated optical amplifier (PGOA) with high gains (≳102), large extinction ratios (∼105), and short aperture times (∆10 psec) is described.
Abstract: A picosecond‐gated optical amplifier (PGOA) characterized by high gains (≳102), large extinction ratios (∼105), and short aperture times (∼10 psec) is described. The active component of the system is a saturable absorbing dye which is irradiated by a high‐intensity ultrashort laser pulse. The technique is illustrated by simultaneously gating and amplifying a weak picosecond continuum pulse propagating through a scattering medium. Performance characteristics of the PGOA and ultrafast shutters are compared.

13 citations


Journal ArticleDOI
TL;DR: In this paper, analytical and numerical results for two-photon fluorescence in an attenuating medium were obtained with respect to the measurement of ultrashort laser pulses, and these results were interpreted with regard to the measurements of laser pulses.
Abstract: Analytical and numerical results are obtained for two‐photon fluorescence in an attenuating medium. Cases of one‐ and/or two‐photon attenuation are considered. These results are interpreted with respect to the measurement of ultrashort laser pulses.

10 citations


Journal ArticleDOI
TL;DR: A compact device capable of selecting pulses from a cw mode-locked pulse train is described, and a single pulse, a repetitive train of pulses, or a random pulse may be selected.
Abstract: A compact device capable of selecting pulses from a cw mode-locked pulse train is described. A single pulse, a repetitive train of pulses, or a random pulse may be selected. Tests results are given.

9 citations


Journal ArticleDOI
TL;DR: In this paper, an analysis of photon-echo behavior using single-mode excitation is given, and it is shown that in the presence of extreme inhomogeneous broadening, the excitation with long pulses may display a complicated echo shape.
Abstract: Analysis of photon-echo behavior using single-mode excitation is given. It is shown that in the presence of extreme inhomogeneous broadening, the excitation with long pulses may display a complicated echo shape. Two typical cases are treated, one in which the pulses have equal length, and the other in which the pulses have equal electric-field strength. These show a large difference in echo behavior, especially for large excitation pulse areas.

8 citations


Journal ArticleDOI
TL;DR: In this paper, the authors consider a class of devices that use a saturable absorber irradiated by an optical control pulse, or gating pulse, to alter the shape of a transmitted optical signal.
Abstract: This paper discusses characteristics of a class of devices that use a saturable absorber irradiated by an optical control pulse, or gating pulse, to alter the shape of a transmitted optical signal. We consider two device geometries: a longitudinally gated cell, in which signal and gate beams are nearly parallel, and a transverse cell, in which the medium is bleached by a gating pulse applied at right angles to the signal beam. The longitudinal device permits synthesis of rising exponential signal pulses with arbitrary, subnanosecond time constants. The transverse geometry can provide pulses of complex shape and permits independent optimization of several device parameters. The dynamics of the saturable absorber (with particular emphasis on liquid dye systems) is analyzed in detail, and a pulse-shape synthesis procedure is outlined. Spurious nonlinear effects are considered, and an example of pulse shaping for laser-driven fusion is given.

6 citations


Journal ArticleDOI
TL;DR: Pulse propagation in a photodissociative iodine laser amplifier is investigated both experimentally and numerically in this article, and it is found that pulse shortening by gain saturation is impractical for sub-nanosecond pulses.
Abstract: Pulse propagation in a photodissociative iodine laser amplifier is investigated both experimentally and numerically. Pulse reshaping and shortening occur in agreement with theory. It is found that pulse shortening by gain saturation is impractical for subnanosecond pulses.

6 citations


Patent
02 Jul 1975
TL;DR: In this paper, a train of d.c. pulses having a pulse repetition frequency which is directly proportional to and, which is a multiple of the speed of sound of the material was used to test and calibrate ultrasonic flaw detectors.
Abstract: Methods of and apparatus for simulating ultrasonic pulse echoes are used to test and calibrate ultrasonic flaw detectors by simulating a train of radio frequency pulses, having a pulse repetition frequency which is indicative of both the speed of sound in a material under test and the thickness of that material. This is accomplished by generating a train of d.c. pulses having a pulse repetition frequency, which is directly proportional to and, which is a multiple of the speed of sound of the material The pulse repetition frequency is also inversely proportional to the thickness of the material. The d.c. pulses are used to drive a radio frequency pulse generator and a pulse modulator. The outputs of the radio frequency generator and pulse modulator are then combined to produce a signal having an amplitude envelope, which simulates a series of ultrasonic pulse echoes.

Patent
27 May 1975
TL;DR: In this article, it was shown that the compression ratio is equal to the ratio of the velocity of light divided by the product of the velocities of sound in the crystal times the absolute value of birefringence of the crystal.
Abstract: There is disclosed a pulse processing method and apparatus for compressing or changing the time scale of signal information represented by the modulation of a pulse of carrier energy which method and apparatus utilizes a crystal through which both a pulse of radio frequency acoustic energy and a pulse of polarized optical energy are simultaneously and colinearly transmitted to scatter energy in the optical pulse from one polarization state into the orthogonal polarization state. The crystal output is thus comprised of two optical pulses. One is the pulse having the original state of polarization and the other is the pulse resulting from the energy scattered to the orthogonal polarization state. The optical energy of rotated polarization is modulated in a fashion reproducing the modulation of the ultrasonic wave by which it is scattered. Furthermore, a short optical pulse can pass through the ultrasonic wave in a time short compared to the duration or length of the ultrasonic wave in the crystalline device. In so doing it reads the modulation of the acoustic pulse and transfers it to a time compressed pulse scale on the scattered optical output pulse. It is shown that the compression ratio is equal to the ratio of the velocity of light divided by the product of the velocity of sound in the crystal times the absolute value of birefringence of the crystal. If both the optical and acoustic pulses are passed through the crystal colinearly and in the same direction, the device takes a time function represented by the acoustic pulse, reverses it in time and compresses it by the ratio of light velocity to sound velocity thus producing a compressed inverse function. If the acoustic pulse and the light pulses are transmitted through the crystal colinearly but in opposite directions, the device takes a time function and without reversing it, compresses it in substantially the same ratio. The device may be applied, for example as a means of improving the signal-to-noise ratio, detection ratio and range resolution in radar systems or the like.

Journal ArticleDOI
TL;DR: In this article, the shadow photography method was used in a study of the development of filamentary damage regions which appeared in a KDP crystal under the action of a single ultrashort laser pulse.
Abstract: The shadow photography method was used in a study of the dynamics of, the development of filamentary damage regions which appeared in a KDP crystal under the action of a single ultrashort laser pulse. These damage filaments appeared in the focal region, and they grew in the direction of propagation of the pulse and in the opposite direction. In the former case the growth of the damage region ended earlier. A comparison was made of the damage threshold of various transparent materials (K-8 glass, fused quartz, and KDP crystals) at two wavelengths (1.06 and 0.53 ?).

Journal ArticleDOI
TL;DR: In this article, a novel system for generating single tunable ultrashort light pulses of high power is described, where the pulse train from a mode-locked flashlamp pumped dye laser passes through an amplifier, which is pumped by an N2 laser.



Journal ArticleDOI
TL;DR: In this paper, the authors used phase sensitive detection methods to accurately determine the broadening and center frequency measurements at various pressures for different perturbers and for different polarizations between the laser and Stark fields.
Abstract: transition of the 0 + v g band and the R(2, 1) transition of the v 3 --f 2v3 band.' Shown in Table I are the transitions observed to date for the above described case. The column describing the relative coupling is determined from the magnitude of the direction cosine matrix elements associated with the two photon absorg tion cross section. Through the use of phase sensitive detection methods, we were able to accurately determine the broadening and center frequency measurements at various pressures for different perturbers and for different polarizations between the laser and Stark fields. This information is listed in Table 11. The pressure broadening mechanisms constitute those processes which transfer angular momentum. These mechanisms are of the energy changing (TI) type and include molecular reorientation and rotational transitions. The shift of the resonant frequency is determined by the difference in the collisional perturbations on the initial and final states of the transition under investigation. Elaboration on the aforementioned processes are presented and compared with the results of Table 11.

Journal ArticleDOI
Chinlon Lin1, C. V. Shank
TL;DR: In this paper, a general technique for sub-nanosecond pulse generation from laser−pumped dye lasers is described, which makes use of the resonator transients in the form of damped relaxation oscillation and can be controlled by proper choices of photon cavity decay time and pumping level.
Abstract: A general technique for subnanosecond pulse generation from laser−pumped dye lasers is described. The technique makes use of the resonator transients. These transients are in the form of damped relaxation oscillation and their durations can be controlled by proper choices of photon cavity decay time and pumping level. High−repetition−rate tunable dye laser pulses of subnanosecond durations have been obtained from N2 laser pumped dye solutions in the near−uv and visible regions. These tunable subnanosecond pulses should provide useful excitation sources for nanosecond absorption and fluorescence spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the suitability of these chemical lasers for applications such as laser communications, where frequency and amplitude stability is required over very long time periods, active stabilization techniques were investigated.
Abstract: gated using a scanning Fabry-Perot interferometer. The data consisted of multiple scans of a single Fabry-Perot fringe which were photographically recorded over various exposure times. The frequency variations exhibited by these multiple traces indicate that over a period of 1 sec, long term frequency stabilities of better than 3 parts in 10’ are achievable with a relatively straight forward resonator design. Similar data obtained over shorter time durations indicated an approximate inverse square root dependence upon the observation time. For times shorter than 100 msec, the frequency stability was less than 1 part in 10’ and could not be resolved by the present scanning FabryPerot technique. I The frequency spectrum produced by heterodyning two identical H F mixing lasers, both operating on P,-1 (6) , was displayed on a low frequency spectrumaqalyzer. Thedataindicated that the frequency stability of the present device is predominantly limited by the low frequency disturbances coupled to the mechanical resonator structure from the environment and not by the mixing within resonator medium. Consequently, significantly better frequency stability should be attainable by further sophistication of the resonator’s mechanical properties before the influence of the active medium imposes limitations upon the device’s performance. To evaluate the suitability of these chemical lasers for applications such as laser communications, where frequency and amplitude stability is required over very long time periods, active stabilization techniques wereinvestigated. A particularly attractive technique which was developed is that of locking the HF laser output to the minimum of the Lamb dip by using active dither stabilization. The laser cavity was tuned in frequency such that the dither was symmetrically applied about the minimum of the Lamb dip which was located at the center of the 300 MHz Doppler broadened gain curve. A comparison of the open and close loop performance of the chemical laser was made. In the open loop mode when the cavity length was changed due to thermal or mechanical influences, substantial variations in both the intensity and frequency of the laser were observed. However, when the laser was actively locked to the Lamb dip by means of an electronic servo system, the laser intensity and frequency remained constant within the limits associated with the dither stabilization over periods in excess of an hour and for a wide range of conditions. Data will also be presented comparing the performance of a premixed, CW electricallyinitiated, chemical laser* with that of the chemical mixing laser and the suitability of these CW chemical lasers as frequency-stable local oscillators for mid-IR heterodyne applications will be discussed.


Dissertation
01 Jan 1975
TL;DR: In this article, a study of temporal broadening of light pulses in multimode optical fiber waveguides has been carried out, where a mode-locked He-Ne laser and a modelocked ruby laser were used as the sources to produce the pulses of light and, in addition, with the aid of an optical shutter, an optical sampling 'oscilloscope' with picosecond time resolution was constructed to enable a high resolution of the output pulse.
Abstract: An experimental study of temporal broadening of light pulses in multimode optical fibre waveguides has been carried out. A mode-locked He-Ne laser and a mode-locked ruby laser were used as the sources to produce the pulses of light and, in addition, with the aid of an optical shutter, an optical sampling 'oscilloscope' with picosecond time resolution, was constructed to enable a high resolution of the output pulse. Many solid and liquid-cored fibres, all having sharp core-cladding boundaries, were investigated for the effect upon pulse broadening (dispersion) of launching beam semi-angle, launching angle of incidence, wavelength of the launched probe pulse, peak pulse power of the probe pulse, length of the fibre, launched spot-size at the fibre input end face etc. Pulse dispersion was strongly dependent on the input beam semi-angle and further, for large angles, the output pulse was asymmetrical with the trailing part sustaining the major dispersion. A ray propagation model gave good agreement with the experimental results. It was further found that under similar launching angle, dispersion was essentially independent of the wavelength. A narrow input angle can be converted to a wider angle soon after launch and thereafter the dispersion is a linear function of length. This has also been found in long lengths of liquid-cored fibres. Non-linear effects can occur in optical fibres if the peak power in the launched pulse is high. Therefore it is shown which parameters are important and must be cited when quoting the dispersion of a particular fibre, and how the propagation characteristics of optical fibres can be elucidated with reasonable confidence by performing relatively simple measurements, hence providing the necessary and important feedback for the production of fibres having even greater transmission capacities.


Journal ArticleDOI
TL;DR: The Livermore COz laser system, Valkyrie as mentioned in this paper, was constructed to provide an experimental facility capable of delivering 50 J in a diffraction limited beam at 10.6 pm in 1 nsec.
Abstract: The Livermore COz laser system, Valkyrie, was constructed to provide an experimental facility capable of delivering 50 J in a diffraction limited beam at 10.6 pm in 1 nsec. This device has met all of its design goals and is in operation as a target irradiation facility. On a typical day, Valkyrie provides 40 J 10 X in 1 nsec at a repetition rate limited by the time required to replace targets. In order to design Valkyrie a CO, amplifier modeling computer program predicted the output of individual amplifier modules. This information was fed into a laser system simulation routine in order to determine amplifier staging. Once specified and manufactured, Valkyrie's amplifiers were subjected to an exhaustive series of tests. Small signal gain as a function of gas mixture, E/n, pump pulse duration, and spatial position was measured. Valkyrie's oscillator employs a specially designed UV preionized TFA gain medium (Lumonics 142A), a Ge Brewster's angle acoustooptic mode-locker, and an NaCl etalon as an output mirror. This oscillator generates a burst of 1 nsec duration pulses with peak pulse energies in excess of 50 mJ distributed reproducibly among -six rotational lines centered on the P20 transition of the 10.4 pm hand. A single pulse is selected by a switch-out assembly consisting of a laser triggered spark gap and CdTe Pockel's cells. The pulse is then directed through a second Lumonics 142A which serves as a preamplifier and into a 3 x Keplerian beam expander with a spatial filter at its focus. Expended and collimated, the pulse propagates through a nine centimeter aperture UV-preionized TEA amplifier (Lumonics 602A) followed by two eleven centimeter aperture cold-cathode E-beam sustained amplifiers operated at two atmospheres. Emerging in the target area, the pulse contains 50 J in 1 nsec with an approximately Gaussian spatial intensity distribution. Two NaCl beamsplitters which are wedged and anti-reflection

Journal ArticleDOI
TL;DR: In this article, the authors used a very 400 joule slave oscillator in an unstable configuration for the resonator to produce multigigawatt (MW) pulses.
Abstract: Fig. 2 illustrates the importance of determining the proper attenuation of the propylene cell. In this figure, the attenuation was too strong and the input signal to the slave was below the noise for spontaneous emission. If the input signal is too strong, the gain switching effect of the second laser is then attenuated. Optimum conditions were determined by varying the pressure of the propylene in the 30 cm cell. It has been experimentally verified that this system works just as well as long as the ratio of the length of the first laser to that of the second forms a simple ratio : 2, f ,+.. .. This permits the use of higher energy slave oscillators without complication. The operation with unstable resonators has also been demonstrated. Another variation which has been successfully demonstrated is the injection of a unique pulse into the second laser. This has been accomplished using a GaAs active polarizer followed by a saturable absorber (SF,) to further attenuate the unwanted peaks. This new method for producing multigigawatt pulses imposes itself not only by its reliability but by its simplicity. Its potential is far from being fully developed as no critical experimental limitations are as yet evident. In fact, we are confident of some achieving much better results with a very 400 joule slave oscillator in an unstable configuration for the resonator.