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Dual/Multi-Channel Graded Index Lens Fiber-Optics Coupling

IP.com Disclosure Number: IPCOM000044170D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Balliet, L: AUTHOR [+2]

Abstract

This article describes an arrangement which makes a single fiber multi-drop bus system feasible by efficiently coupling light energy into a fiber while simultaneously tapping receiver energy from the fiber. It solves the problem of dual-wave length/multi-channel coupling to and from a single fiber. Figs. 1A, 1B, 1C and 1D show the basic coupling mechanism for three types of devices. The coupling mechanism uses quarter pitch graded index lenses of normal construction to collimate light from a communication fiber 15. Referring to Fig. 1A, a graded index lens 1 is cut at nominally quarter pitch with a prism mounted at the end with a 45-degree polished facet 2 that reflects light. The facet 2 is formed by a combination of etching, grinding and polishing.

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Dual/Multi-Channel Graded Index Lens Fiber-Optics Coupling

This article describes an arrangement which makes a single fiber multi-drop bus system feasible by efficiently coupling light energy into a fiber while simultaneously tapping receiver energy from the fiber. It solves the problem of dual-wave length/multi-channel coupling to and from a single fiber. Figs. 1A, 1B, 1C and 1D show the basic coupling mechanism for three types of devices. The coupling mechanism uses quarter pitch graded index lenses of normal construction to collimate light from a communication fiber 15. Referring to Fig. 1A, a graded index lens 1 is cut at nominally quarter pitch with a prism mounted at the end with a 45-degree polished facet 2 that reflects light. The facet 2 is formed by a combination of etching, grinding and polishing. The device to be coupled is interfaced through the surface 3 of the prism opposite the facet. A second graded index lens 5 can be used with this type of device to optimize coupling, as shown in detail in Fig. 1E. A light emitting device (LED) 4 or photodiode detector 12 of planar surface construction is utilized. In the embodiment shown in Fig. 1B, a spherical lens 16 may also be used. The lens focuses the light to and from the sensitive area of the device 4. Collimated light rays 6 reflect from the 45-degree facet 2 by virtue of the principle of total internal reflection and are coupled to the fiber 15 which is located at the focal point of the graded index lens 1. Figs. 1C and 1D show coupling to edge-emitting LED 7 and laser 8, respectively. Coupling to these types of devices is more optionally done via cylindrical len...