Document Type


Publication Date



Physics and Computer Science


The Gaussian approximation that is typically used to estimate single-mode fiber microlens performance is investigated. It is applied to hemispheric lenses on two types of tapered single-mode fiber. Theoretical and experimental results are compared. The first type of taper, which is fabricated by pulling a fiber while it is melted, has a tapered core and a tapered cladding. The second type of taper, which is fabricated by etching the cladding, has a tapered cladding only. For a tapered-core fiber, coupling to the cladding-guided modes and the finite radius of curvature of the wave front before the lens must be considered to predict the lens spot size accurately, whereas the spot size of a tapered-cladding lens can be predicted from the lens diameter alone. Thus the spot size of a lens on a tapered-cladding fiber is easier to predict and control than that of a lens on a tapered-core fiber. It is also shown that the usual theory used to predict the spot size gives accepted values for tapered-cladding lenses but not for tapered-core lenses.


This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.