Optical Fibre Magnetometer Using A Stabilised Semiconductor Laser Source

R. H. Pratt; R. E. Jones; P. Extance; G. D. Pitt; K. W. Foulds

doi:10.1117/12.945057

12 November 1984 Optical Fibre Magnetometer Using A Stabilised Semiconductor Laser Source

R. H. Pratt, R. E. Jones, P. Extance, G. D. Pitt, K. W. Foulds

Proceedings Volume 0514, 2nd Intl Conf on Optical Fiber Sensors: OFS'84; (1984) https://doi.org/10.1117/12.945057
Event: 2nd International Conference on Optical Fiber Sensors, 1984, Stuttgart, Germany

Abstract

Fluctuations in the operating frequency of semiconductor lasers produce intensity noise in interferometric sensors with a path length difference. This noise has a 1/f frequency dependence and its magnitude increases in direct proportion to interferometer path length difference(1). An approximate value of the amplitude of these fluctuations, for the STL GaAlAs laser used to drive the magnetometer, is 105 Hz measured at a detection frequency of 1 kHz. To achieve a minimum detectable phase of 10-6 radians in a fibre interferometer with such a laser it is necessary to balance the interferometer arms to better than 1 mm. In order to reduce this noise source some authors(2) have reported locking the laser frequency to an external Fabry-Perot cavity by controlling the laser drive current. This is possible since the output frequency of a solid state laser is linearly dependent upon drive current. Compared with unstabilised lasers, improvements of 20 dB in laser output noise spectra have been reported using this technique. Similar results have been obtained in this work, but an all-fibre Fabry-Perot interferometer replaced the bulk optics device. This stabilised laser then acted as a source for a Mach-Zehnder sensing interferometer.

Citation Download Citation

R. H. Pratt, R. E. Jones, P. Extance, G. D. Pitt, and K. W. Foulds "Optical Fibre Magnetometer Using A Stabilised Semiconductor Laser Source", Proc. SPIE 0514, 2nd Intl Conf on Optical Fiber Sensors: OFS'84, (12 November 1984); https://doi.org/10.1117/12.945057

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available