Coupling and cross-talk effects in 12-15 microm diameter single-mode fiber arrays for simultaneous transmission and photon collection from scattering media.
We examine signal degradation effects in fiber arrays from fiber-to-fiber coupling and from cross talk attributable to backscatter from the sample medium originating from adjacent fibers in the array. An analysis of coupling and cross talk for single-mode fibers (SMFs) operating at 1310 nm with different core diameters, interaction lengths, core center spacing, and numerical apertures (NAs) is evaluated. The coupling was evaluated using beam propagation algorithms and cross talk was analyzed by using Monte Carlo methods. Several multimode fiber types that are currently used in fiber image guides were also evaluated for comparative purposes. The analysis shows that an optimum NA and core diameter can be found for a specific fiber center separation that maximizes the directly backscattered signal relative to the cross talk. The coupling between fibers can be kept less than -35 dB for interaction lengths less than 5 mm. The calculations were compared to an experimentally fabricated SMF array with 15 microm center spacing and showed good agreement. The experimental fiber array without a lens was also used in a coherent detection configuration to measure the position of a mirror. Accurate depth ranging up to a distance of 250 microm from the tip of the fiber was achieved, which was five times the Rayleigh range of the beam emitted from the fiber.
Luo
Yuan
Y
Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA.
Castillo
Jose
J
Arauz
Lina
L
Barton
Jennifer
J
Kostuk
Raymond K
RK
D000465:Algorithms; D003198:Computer Simulation; D007368:Interferometry; D009010:Monte Carlo Method; D055095:Optics and Photonics; D010087:Oxides / Q000737:chemistry; D019047:Phantoms, Imaging; D017785:Photons; D012107:Research Design; D012542:Scattering, Radiation; D015398:Signal Transduction
D010087:Oxides