Abstract

The results of a comparative experimental study on the effect of the modal noise induced by lead-in fibers in an extrinsic interferometric system, illuminated by high- and low-coherence light sources, respectively, are reported. When the up-lead fiber was subject to a perturbation, the sensitivity of the system was reduced by 20.9 dB through the use of a high-coherence source, and by 1.8 dB through the use of a low-coherence source. When the down-lead fiber was perturbed, the sensitivity dropped by 30.3 dB and 4.9 dB for high- and low-coherence sources, respectively. The results from the experimental analysis supported qualitatively by simple theory show that the use of a low-coherence light source can greatly suppress the modal noise induced in both the up- and down-lead fibers, if the coherence length of the light source used is less than the optical path difference between two adjacent fiber modes. This shows the practicality of the use of multimode fibers in an interferometric system with a suitable light source.

© 1994 Optical Society of America

Relation between the coherence length and modal noise in a graded-index multimode fiber for white-light interferometric systems

Y. N. Ning, Y. Liu, K. T. V. Grattan, A. W. Palmer, and K. Weir
Opt. Lett. 19(6) 372-374 (1994)

Optimized multiwavelength combination sources for interferometric use

D. N. Wang, Y. N. Ning, K. T. V. Grattan, A. W. Palmer, and K. Weir
Appl. Opt. 33(31) 7326-7333 (1994)

Reciprocal reflection interferometer for a fiber-optic Faraday current sensor

Guido Frosio and René Dändliker
Appl. Opt. 33(25) 6111-6122 (1994)

Analysis of dispersion effects for white-light interferometric fiber-optic sensors

Waclaw Urbanczyk and Wojtek J. Bock
Appl. Opt. 33(1) 124-129 (1994)

Influence of chromatic dispersion on a dual-wavelength passive-homodyne detection method for fiber-coupled interferometers

Hugues R. Giovannini, Serge J. Huard, and Michel R. Lequime
Appl. Opt. 33(13) 2721-2733 (1994)