Title

Foundations for low-loss fiber gradient-index lens pair coupling with the self-imaging mechanism

Authors

Authors

M. van Buren;N. A. Riza

Abbreviated Journal Title

Appl. Optics

Keywords

FERROELECTRIC LIQUID-CRYSTALS; ROD LENSES; DELAY-LINE; SPEED; Optics

Abstract

A fiber-optic collimator that emits a Gaussian beam with its beam waist at a certain distance after the exit face of the lens is labeled a self-imaging collimator. For such a collimator, the waist of the emitted Gaussian beam and its location are partly dependent on the properties of the gradient-index (GRIN) lens. Parameters for the self-imaging collimator are formulated in terms of the parameters of a GRIN lens (e.g., pitch, core refractive index, gradient index, length) and the optical wavelength. Next, by use of the Gaussian beam approximation, a general expression for the coupling power loss between two self-imaging-type single-mode fiber (SMF) collimators is, for the first time to our knowledge, derived as a function of three types of misalignment, namely, separation, lateral offset, and angular tilt misalignment. A coupling experiment between two self-imaging collimators with changing separation distance is successfully performed and matches the proposed self-imaging mechanism coupling loss theory. In addition, using a prism, lateral offset, as well as angular tilt, misalignments are experimentally simulated for a two self-imaging collimator coupling condition by a single collimator reflective test geometry. Experimental results agree well with the proposed loss formulas for self-imaging GRIN lenses. Hence, for the first time to our knowledge, the mathematical foundations are laid for employing self-imaging-type fiber collimators in SMF-based free-space systems allowing optimal design for ultra-low-loss coupling. (C) 2003 Optical Society of America.

Journal Title

Applied Optics

Volume

42

Issue/Number

3

Publication Date

1-1-2003

Document Type

Article

Language

English

First Page

550

Last Page

565

WOS Identifier

WOS:000180483300029

ISSN

1559-128X

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