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Proceedings Paper

Optically induced inductance modulation of a Nb coil
Author(s): Sae Woo Nam; George S. Park; Blas Cabrera; Martin E. Huber
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Paper Abstract

We have designed and tested an optically driven inductance modulator, for use as part of a 1/f noise reduction scheme for SQUID magnetometers. The modulated element is a Nb coil photolithographically patterned on a 6x6 mm silicon chip. The coil is covered by three cocentric superconducting washers, patterned from a layer of PbInAu deposited above the Nb. Leads from the washers extend to a meander region directly below an optical fiber, which is coupled to a diode laser. With the laser off, the superconducting washer loops diamanetically shield the coil, and the coil has a low effective inductance. With the laser on, the meander is driven normal and the superconducting washer loops are open, greatly reducing the shielding. The coil then has a high effective inductance. The inductance is measured using a SQUID connected to the coil. Using this method, we have modulated the coil inductance from 2 (mu) H to nearly 20 (mu) H. By using four of these inductance modulators, we plan to fabricate a low- noise chopping network at the input of a SQUID, which can be used to reduce the 1/f noise in SQUID measurements.

Paper Details

Date Published: 2 July 1994
PDF: 8 pages
Proc. SPIE 2160, Superconductive Devices and Circuits, (2 July 1994); doi: 10.1117/12.181002
Show Author Affiliations
Sae Woo Nam, Stanford Univ. (United States)
George S. Park, Stanford Univ. (United States)
Blas Cabrera, Stanford Univ. (United States)
Martin E. Huber, Univ. of Colorado/Denver (United States)

Published in SPIE Proceedings Vol. 2160:
Superconductive Devices and Circuits
Robert A. Buhrman; John T. Clarke; Ken Daly; Roger H. Koch; Jerome A. Luine; Randy W. Simon, Editor(s)

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