Showing papers by "Gerard Mourou published in 1983"

Subpicosecond electrical sampling

Abstract: We report on the recent advances of an electrooptic sampling technique for the characterization of electrical transients that has now achieved an unprecedented temporal resolution of less than 1 ps. Voltage sensitivity is on the order of 50 μV. A lithium tantalate traveling wave Pockels cell is employed in conjunction with a high repetition rate subpicosecond laser system.

Measurement of electrical signals with picosecond resolution

Abstract: Electrical signals are measured (analyzed and displayed) with subpicosecond resolution by electro-optic sampling of the signal in an electro-optic crystal, the index of which changes in response to the electric field produced by the signal, in accordance with the Pockels effect. The crystal is disposed adjacent to a transmission line along which the signals propagate the line may be a coplanar wave guide having a plurality of parallel strips of conductive material on the surface of the crystal. The crystal may be disposed adjacent to and in the fringe field of a line on a substrate, which may be part of an integrated circuit, for measuring signals propagating along the line during the operation of the circuit. A beam of short optical (laser) sampling pulses in the picosecond range is focused so that the region where the beam is confocal is disposed where the field is parallel in the crystal. The confocal region (where the optical wavefront is planar is preferrably close to the surface of the crystal and perpendicular to the optical axis of the crystal. The optical pulses transmitted through the crystal are processed to provide a display affording a measurement of the electrical signal.

Synchronous amplification of subpicosecond pulses

Abstract: In high-gain dye amplifiers, the effective storage time of the gain medium is only a few hundred picoseconds. Therefore, efficient amplification of ultrashort pulses places a stringent requirement on the synchronization between the pump pulse and the pulse to be amplified. We present a technique of short pulse generation using a dye laser synchronously pumped by a frequency-doubled CW mode locked Nd:YAG laser. Pulses as short as 70 fs are produced. The short optical pulses are subsequently amplified with two different synchronous amplification schemes using 100 ps pulses to establish the gain in the dye amplifier stages. Subpicosecond pulses with energies from a few hundred nanojoules at 500 Hz to a few hundred microjoules at 7 Hz can be obtained.

Subpicosecond Electrical Sampling

Abstract: We report on the recent advances of an electrooptic sampling technique for the characterization of electrical transients that has now achieved a temporal resolution of .5 ps. Voltage sensitivity is on the order of 50 μV. The electrooptic material is used in a traveling wave geometry as well as in an electrodeless manner, where the electrooptic material probe the fringing field associated with the signal as it propagates along the transmission line.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Picosecond Electron Diffraction

Abstract: Electron diffraction on the picosecond time scale is demonstrated using a picosecond photoelectron burst generated by an optical pulse incident on the front end of a streak camera. Because of the picosecond synchronization between the optical and electron pulses, this technique makes possible the study of laser-induced structural kinetics in the picosecond time domain.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Transient response of tin microstrips to supercritical current pulses

Abstract: We have measured the transient response of tin microstrips to short current pulses whose amplitude exceeded the dc critical current I c of the sample. The current pulses were generated by an electro-optic switching technique. The voltage across the microstrip was measured indirectly by integrating the sample into a transmission line and measuring the transmission characteristics. For a fixed pulse duration, no voltage was measured until a threshold I c1 (>I c ) was reached. Above I c1 , the voltage developed at a delay time of τ d . When current amplitude exceeded a second threshold I c2 , the voltage onset occurred with no observable delay. These results were partially explained by existing theories that employed TDGL calculations.

Picosecond X-ray generation from picosecond photoelectron pulses

Abstract: : An x-ray source capable of producing picosecond range pulse widths at high repetition rates is demonstrated. Picosecond light pulses are converted to piicosecond electron pulses which are then accelerated onto a target to produce x-rays. Using a conventional PIN diode, a time duration of less than 300 psec is observed for Al Kalpha x-ray emission. This x-ray source has potential applications for fast dynamic measurements of light-induced structural changes and for characterizing picosecond x-ray diagnostic equipment.