Showing papers by "Gerard Mourou published in 1987"
TL;DR: In this paper, the process of electron-phonon energy transfer was time resolved and was observed to be 1--4 ps increasing with the laser fluence, and non-equilibrium electron-lattice temperatures were observed.
Abstract: Amplified 150--300-fs laser pulses are applied to monitor the thermal modulation of the transmissivity of thin copper films. Non- equilibrium electron-lattice temperatures are observed. The process of electron-phonon energy transfer was time resolved and was observed to be 1--4 ps increasing with the laser fluence.
510 citations
TL;DR: In this article, the authors used fraction gratings in both positive and negative group velocity dispersion configurations to expand and compress an optical pulse, achieving an expansion/compression factor of 1000 times, from 85 fs to 85 ps and back.
186 citations
Patent•
05 Oct 1987TL;DR: In this paper, a method for transmitting high energy sub-picosecond pulses through single-mode optical fiber without stimulating nonlinear effects as are caused by self-phase modulation or Raman generation, which method increases the average power handling capacity of the fiber.
Abstract: A method for transmitting high energy subpicosecond pulses through single-mode optical fiber without stimulating nonlinear effects as are caused by self-phase modulation or Raman generation, which method increases the average power handling capacity of the fiber. The optical pulses, which may be modulated to carry data, as by pulse code modulation, are increased in temporal width before launching into the fiber. The output pulses from the fiber are compressed. Since the nonlinear effects are related to the peak power of the pulses, these effects are avoided while increasing the average power and allowing the use of the available bandwidth of the fiber thereby enabling greater data transmission rates.
59 citations
TL;DR: In this article, a method for determining the modal dispersion of gigahertz-bandwidth pulses on microstrip transmission lines is described, with very good agreement noted between experimental pulse shapes and numerical simulations.
Abstract: A method for determining the modal dispersion of gigahertz-bandwidth pulses on microstrip transmission lines is described. We have investigated the evolution of temporal waveforms propagating on microstrips, with very good agreement noted between experimental pulse shapes and numerical simulations. The resulting pulse distortion contributed to a pulse-shaping application where 100-ps rise times were stretched to the nanosecond durations necessary to control the shape of high-energy optical pulses used in fusion research. The tunability of the shape of the rising edge was investigated through variation of the stripline geometry and the substrate material. Additional effects due to high-frequency attenuation in several dipolar liquid dielectrics were substantiated experimentally, and the relevance of the results has been discussed.
39 citations
TL;DR: In this paper, the transient propagation characteristics of superconducting and normal indium lines in the picosecond regime were studied using a cryogenic electro-optic sampling technique, and an algorithm was developed that accurately describes all of the experimental findings.
Abstract: Using a cryogenic electro‐optic sampling technique, we have studied the transient propagation characteristics of superconducting and normal indium lines in the picosecond regime. Transient dispersion effects, including increased rise time and increased pulse width, the introduction of ringing on the waveform, and a novel ‘‘pulse sharpening’’ were observed. A model that takes into consideration the effects of modal dispersion and superconducting complex conductivity was established, and an algorithm was developed that accurately describes all of the experimental findings.
28 citations
TL;DR: In this article, a fully cryogenic electro-optic sampler was developed by integrating and immersing in superfluid helium both the photoconductive switch and the birefringent lithium tantalate sensor.
Abstract: We have developed a fully cryogenic electro-optic sampler by integrating and immersing in superfluid helium both the photoconductive switch and the birefringent lithium tantalate sensor. The ultimate temporal response of the system as determined by measuring the transient onset of photoconductivity in a GaAs switch was less than 400 fs. The system was arranged into a coplanar transmission line geometry and used to probe the switching of a 30 × 30 μm2Josephson tunnel junction. Both time-dependent waveforms of the transmitted signal and current-voltage characteristics of the junction switched by a picosecond input pulse were measured. The results were compared to transient simulations based on the resistively and capacitively shunted junction model, and showed that: the initial junction response was limited only by the time integral of the input pulse, the switched voltage was proportional to the total charge delivered by the pulse, and there was no turn-on delay time. This represents the first, in situ measurement of the response of an unbiased Josephson tunnel junction to a stepped, picosecond pulse.
17 citations
01 Jan 1987
TL;DR: In this article, the authors show that ultrafast optical techniques have made possible the direct investigation of basic nonstationary transport, i.e., velocity overshoot and resonant tunneling, which governs the operation of modern high-speed devices.
Abstract: We show that ultrafast optical techniques have made possible the direct investigation of basic nonstationary transport, ie velocity overshoot and resonant tunneling, which governs the operation of modern high-speed devices
5 citations
01 Dec 1987
TL;DR: In this article, a technique d'amplification d'impulsions a derive de frequence rend possible l'extraction de l'energie de maniere efficace dans des systemes d'AMplification extremement compacts.
Abstract: Des impulsions d'une duree de 1 ps ont ete amplifiees jusqu'au niveau du terawatt par un systeme tres compact a verre dope au neodyme base sur l'utilisation de la technique d'amplification des impulsions a derive de frequence. La divergence du faisceau est egale a deux fois la limite de la diffraction, donnant a cette source une brillance de 2 x 10+ 18 W/(cm 2. sr), ce qui constitue la brillance la plus elevee jamais reportee a ce jour. La technique d'amplification d'impulsions a derive de frequence rend possible l'extraction de l'energie de maniere efficace dans des systemes d'amplification extremement compacts. L'amplification des impulsions a derive de frequence a ete demontree sur neuf ordres de grandeur, du nanojoule jusqu'au niveau du joule. En utilisant une chaine d'amplification a verre au neodyme de grandes dimensions, il devrait etre possible d'etendre cette technique a l'amplification d'impulsions de cent femtosecondes jusqu'au niveau d'une centaine de joules, generant ainsi une puissance instantanee de l'ordre du petawatt. La focalisation ulterieure de ces impulsions pourrait alors donner naissance a des intensites de l'ordre de 1023 W/cm2, 5 ordres de grandeurs au-dessus des performances actuelles.
5 citations
TL;DR: In this article, the authors studied the sub-picosecond propagation characteristics of indium coplanar transmission lines and found that the predominant effect was due to modal dispersion resulting from the dielectric mismatch at the transmission line and substrate interface.
Abstract: We have studied the subpicosecond propagation characteristics of indium coplanar transmission lines. As the transients propagated along the striplines, they exhibited stretched rise time, increased pulse width, and entry of a ringing component. In addition, we observed a "pulse sharpening" for the first time at short propagation distances. It was found that these results could not be fully accounted for by invoking the Mattis-Bardeen theory of microwave conductivity alone. Rather, the predominant effect was due to modal dispersion resulting from the dielectric mismatch at the transmission line and substrate interface. Theoretical results are successfully compared with the experimental findings.
4 citations
Proceedings Article•
26 Apr 1987
2 citations
TL;DR: In this paper, a new approach to time-domain reflectometry using picosecond electro-optic sampling and counter-propagating electrical pulses on a coplanar transmission line is proposed.
Abstract: We propose a new approach to time-domain reflectometry utilising picosecond electro-optic sampling and counter-propagating electrical pulses on a coplanar transmission line. This method enables direct acquisition of the incident and reflected waveforms at the interface between a device and transmission line without requiring temporal separation between the waveforms or deconvolution of the effect of the transmission line on the waveforms.
01 Dec 1987
TL;DR: The first time-domain measurements on millimeter-wave monolithic microwave integrated circuits (MMIC) have been accomplished using noncontact electro-optic sampling as discussed by the authors, employing a tiny crystal of lithium tantalate, allowing the extraction of voltage waveforms from arbitrary locations in integrated circuits.
Abstract: The first time-domain measurements on millimeter-wave monolithic microwave integrated circuits (MMIC) have been accomplished using noncontact electro-optic sampling. The technique, employing a tiny crystal of lithium tantalate, allows the extraction of voltage waveforms from arbitrary locations in integrated circuits. One study, of a Texas Instruments MMIC amplifier, has determined the response of a narrow-band circuit to have a center frequency of 32.5 GHz.
01 Oct 1987
TL;DR: In this article, experimental and numerical studies of the dynamics of the Josephson tunnel junction driven by picosecond current pulses are reported. And the observed behavior is explained in terms of the "ccritical pulse charge" concept.
Abstract: We report experimental and numerical studies of the dynamics of the Josephson tunnel junction driven by picosecond current pulses. Both single pulse switching, and the response to the train of pulses are discussed. The observed behavior is explained in terms of the “ccritical pulse charge” concept.
22 Sep 1987
TL;DR: In this paper, it was shown that it is possible to generate optical pulses of less than 10 fs duration corresponding to only a few optical cycles, which can be used to characterize electrical waveforms with a few hundred femtosecond resolution.
Abstract: Short optical pulses have been involved in a number of areas of science and technology. It is now possible to generate optical pulses of less than 10 fs duration corresponding to only a few optical cycles. One of the most important applications of these short optical pulses is in electronics, where, in conjunction with the electro-optic effect, electrical waveforms now can be characterized with a few hundred femtosecond resolution - corresponding to 1 THz in bandwidth. This technique makes possible the characterization in situ of high-speed optoelectronic and electronic devices as well as circuits operating in the picosecond time scale or 100 GHz frequency domain.