The effects of fiber coupling and fiber length on photocurrent fluctuations are studied when the light of a laser diode transmitted to and from a dynamic turbid medium by a step-index multimode fiber is studied. When the laser light is coupled asymmetrically, filling only the higher-order modes, the photocurrent fluctuations are suppressed significantly when fiber lengths of as much as 16 m are added between the laser and the medium. Addition of as much as 16 m of detection fiber, or any fiber in the case of symmetric light coupling, leads to much less or no suppression of the photocurrent fluctuations.
© 2004 Optical Society of America
Original Manuscript: September 11, 2003
Revised Manuscript: January 5, 2004
Published: April 1, 2004
Anna L. Petoukhova, Ester Cleven, Frits F. M. de Mul, and Wiendelt Steenbergen, "Suppression of dynamic laser speckle signals in multimode fibers of various lengths," Appl. Opt. 43, 2059-2065 (2004)