Short-duration Current Pulses Research Articles

Fast pulsing of single heterojunction laser diodes

When pumping single heterojunction pulsed lasers with short duration current pulses the optical output power is often significantly reduced. This is caused by an increase in the threshold current of the device which is dependent on the temporal characteristics of the pumping current waveshape. This paper presents the results of both a theoretical, and practical study to examine the performance of lasers pumped by current pulses of 1 to 16 ns duration. Measurements have been performed on a number of laser devices using both an avalanche photodiode/sampling oscilloscope and a streak camera based receiver to monitor the laser output. Comparison with theoretical predictions shows good agreement.

Detection of Strong Shock Waves with Plastic Tapes

A simple and inexpensive method for detecting the arrival of a strong shock wave at a surface is described. A thin layer of plastic tape produces a short duration current pulse when subjected to a plane shock wave. When a layer of plastic tape approximately 0.1 mm thick is fastened between an aluminum plate and a copper electrode, a 150 kilobar shock wave propagating from the aluminum into the tape produces a 10 V pulse across a 50 Ω load from an electroded area of 1.25 cm2.

Magnetic tape digital recording for nuclear research

The paper describes two magnetic tape digital recording techniques developed for nuclear physics research. Both 1 in. 16-track and ? in. 4-track systems are used with maximum bit packing densities of 200 and 400/in, respectively. The tape writing and reading technique uses a return to zero method chosen to facilitate ?drop out? detection; a ?0? is written by a short duration current pulse of one polarity and a ?1? but a similar pulse of reverse polarity. The absence of a pulse on any track during reading indicates a ?drop out? and the particular event is then rejected. This error check permits the use of tape systems with overall drop out performance as bad as 1 in 160 bits.