Abstract

Using very general phase-space formalism applied to a Hamiltonian model of monochromatic light rays with an axial z coordinate as a parameter,^1-3 it is shown that there is a fundamental relation between intrinsic optical losses of expanded-beam fiber-to-fiber coupler/connector and the boundary shape of its 4-D phase-space volume located in the symmetry plane of the system. This relation, based on the so-called time-reversal principle, holds for all axially symmetrical expanded- beam connectors with two twin parts representing the collimator and concentrator. Thus this principle can be applied to any practical fiber-fiber connector including both imaging and nonimaging^2-3 optical systems. The proof of the time-reversal principle is based on comparison of geometrical rays reflected either from phase conjugate or conventional mirrors situated in the symmetry plane of the coupling system (including Liouville theorem). It is shown that for ideal couplers, the angular spectrum of light at any point in the plane of symmetry should have inversion symmetry.

© 1987 Optical Society of America