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Picosecond Optical Auto Correlation Technique Using a Superconducting Switch

IP.com Disclosure Number: IPCOM000053017D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Chi, CCJ: AUTHOR [+2]

Abstract

This article relates to high-speed auto-correlation techniques and more particularly to a picosecond optical auto-correlation technique using a superconducting switch.

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Picosecond Optical Auto Correlation Technique Using a Superconducting Switch

This article relates to high-speed auto-correlation techniques and more particularly to a picosecond optical auto-correlation technique using a superconducting switch.

The voltage output of a constant-current biased superconducting switch is highly nonlinear as the power of the illuminating light pulses from a laser is increased. Fig. 1 shows a superconducting thin film 1 with two superconducting pads 2 to which a source 3 of constant current, Io, is connected. Thin film 1 is illuminated by a laser which provides illumination P of sufficient power to drive film 1 to a normal or non-superconducting state. Fig. 2 shows the voltage output (Vout) vs. the incident power (P) characteristic of thin film 1. As can be seen, the characteristic is an ideal step function.

The present approach uses the nonlinear property of a superconducting switch to replace the conventional nonlinear crystal detector in picosecond optical auto-correlation measurements in the following way: (i) A conventional optical auto-correlation apparatus is used to split a laser pulse into two beams, with one beam having an adjustable delay with respect to the other beam. (ii) The two beams are chopped at two different but commensurate frequencies, e.g., 2f(1) = 3f(2). (iii) Standard lock-in detection is used to monitor the voltage output of a single superconducting switch with a constant current bias, as shown in Fig. 1. The bias is maintained below a certain threshold c...