Showing papers by "Gerard Mourou published in 1979"

High‐power switching with picosecond precision

Abstract: Up to 10 kV have been switched with Si and GaAs laser‐activated switches. We show that in spite of the thermal instability shortcoming experienced in Si, quasi‐dc bias operation can be utilized in a manner which relaxes stringent synchronization requirements. In the case of GaAs the thermal instability is less severe and up to 8 kV dc has been held off and efficiently switched. In both cases, a fast switching time of ∼40 ps is observed. This time is a combination of the laser pulse width, geometry bandwidth, and jitter time. Efficient switching action requires only a few tens of microjoules of laser energy. Electrical pulses ranging from subnanosecond to hundreds of nanoseconds duration have been readily generated.

Active pulse shaping in the picosecond domain

Abstract: Active pulse shaping in the picosecond domain is reported using a fast Pockels cell controlled by an optically driven GaAs electrical switch. The center is sliced out of a long optical pulse, yielding a 70‐psec FWHM pulse with 40‐psec rise and fall times.

Light activated solid state switch

Abstract: A semiconductor body, having deep lying charge carrier trapping centers, as by being doped with a deep-lying impurity to a concentration such that, at cryogenic temperature, the body is capable of holding off a multi-kilovolt DC bias without thermal instability and of switching the bias with picosecond accuracy to generate pulses of selected durations beyond the subnanosecond range when activated by optical pulses, as from a laser, which are incident thereon.

Apparatus for switching high voltage pulses with picosecond accuracy

Abstract: Switching of high voltage pulses (of the order of 10 kV) of durations from about 10μs (microseconds) to 10ms (milliseconds) with picosecond accuracy is accomplished by a laser activated semiconductor switch made up of a body (18) of high resistivity semiconductor material, such as nearly intrinsic silicon, integrated into a wide band (10GHz) geometry, which is part of a transmission line (28). The high bias voltage pulses are obtained by charging the line in synchronism with the generation of the laser pulse. The high voltage bias pulse width can be typically in the range of 10μs- 10ms, and the length of the body (18) is selected so as to prevent thermal breakdown of the semiconductor with such pulse widths. The energy of the laser pulse switches the high voltage to produce a multikilovolt output pulse suitable for driving devices, such as streak cameras or Pockels cells, by the same laser, which need to be synchronized with picosecond accuracy to the laser pulse. The length of the transmission line may be varied to adjust the width of the multikilovolt output pulse.