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Proceedings Paper

External-cavity semiconductor laser sensor
Author(s): O. L. Quan; Y. T. Seng; L. P. Lan; J. T.K. Wah; Andrew Thurairaja Sabaratnam; Gopalkrishna M. Hegde; Ananth Selvarajan
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Paper Abstract

The spectral characteristics of a diode laser are significantly affected due to interference caused between the laser diode output and the optical feedback in the external-cavity. This optical feedback effect is of practical use for linewidth reduction, tuning or for sensing applications. A sensor based on this effect is attractive due to its simplicity, low cost and compactness. This optical sensor has been used so far, in different configuration such as for sensing displacement induced by different parameters. In this paper we report a compact optical sensor consisting of a semiconductor laser coupled to an external cavity. Theoretical analysis of the self- mixing interference for optical sensing applications is given for moderate optical feedback case. A comparison is made with our experimental observations. Experimental results are in good agreement with the simulated power modulation based on self-mixing interference theory. Displacements as small as 10-4 nm have been measured using this sensor. The developed sensor showed a fringe sensitivity of one fringe per 400nm displacement for reflector distance of around 10cms. The sensor has also been tested for magnetic field and temperature induced displacement measurements.

Paper Details

Date Published: 11 November 1999
PDF: 8 pages
Proc. SPIE 3897, Advanced Photonic Sensors and Applications, (11 November 1999); doi: 10.1117/12.369369
Show Author Affiliations
O. L. Quan, Ngee Ann Polytechnic (Singapore)
Y. T. Seng, Ngee Ann Polytechnic (Singapore)
L. P. Lan, Ngee Ann Polytechnic (Singapore)
J. T.K. Wah, Ngee Ann Polytechnic (Singapore)
Andrew Thurairaja Sabaratnam, Ngee Ann Polytechnic (Singapore)
Gopalkrishna M. Hegde, Indian Institute of Science/Bangalore (Singapore)
Ananth Selvarajan, Indian Institute of Science/Bangalore (India)

Published in SPIE Proceedings Vol. 3897:
Advanced Photonic Sensors and Applications
Robert A. Lieberman; Anand Krishna Asundi; Hiroshi Asanuma, Editor(s)

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