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Optical Engineering

Advantages of a new modulation scheme in an optical self mixing frequency-modulated continuous-wave system
Author(s): Daniel Nordin; Kalevi Hyyppae
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Paper Abstract

A new frequency-modulated continuous wave modulation scheme, which gives correct results even when the Doppler shift is larger than the frequency difference associated with the range, is presented and tested with a tunable laser diode and fiber-based system. By inserting a constant frequency region in the modulation scheme, both the magnitude and the sign of all beat frequencies can be determined. When they are known, the correct frequency difference as a result of the range can be calculated. This new scheme gives more freedom when choosing the modulation parameters of the laser, because increasing the modulation frequency, and/or the frequency sweep, to avoid ambiguities resulting from a large Doppler shift no longer becomes necessary. This is especially useful when using a somewhat cheaper laser diode source, since the maximum obtainable modulation frequency and frequency sweep can be somewhat limited. The suggested modulation scheme makes it possible to use some laser diodes in an application they otherwise would not be suited for.

Paper Details

Date Published: 1 May 2002
PDF: 6 pages
Opt. Eng. 41(5) doi: 10.1117/1.1467063
Published in: Optical Engineering Volume 41, Issue 5
Show Author Affiliations
Daniel Nordin, Lulea Univ. of Technology (Sweden)
Kalevi Hyyppae, Lulea Univ. of Technology (Sweden)

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