Browse Prior Art Database

Spheroid Lens at Fiber End

IP.com Disclosure Number: IPCOM000052842D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Gupta, OR: AUTHOR

Abstract

The distance of communications in fiber optics is limited due to the losses in the transmission of the light from the source to the ultimate user. The biggest energy losses occur at the LED (light-emitting diode) and the fiber interface. Mismatch in the geometry and the misalignment of the two results in 12 to 14 dB (decibel) losses.

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Spheroid Lens at Fiber End

The distance of communications in fiber optics is limited due to the losses in the transmission of the light from the source to the ultimate user. The biggest energy losses occur at the LED (light-emitting diode) and the fiber interface. Mismatch in the geometry and the misalignment of the two results in 12 to 14 dB (decibel) losses.

A tremendous amount of effort and money have been spent to reduce the losses. Even the best effort only improves the coupling losses by 2 to 4 dB.

This arrangement improves the efficiency of the coupling and makes the design less sensitive to any misalignment. A spheroid lens 1 is formed at the end of the fiber 2 and is placed in front of the LED 5. The spheroid lens 1 has the same refractive index nl as that of the fiber core 3. The refractive index nl of the core 3 is higher than the refractive index n2 of the cladding 4. The core 3 is embedded in the cladding 4. The diameter of the spheroid lens 1 is greater than the diameter of the fiber. Spheroid lens 1 and fiber 2 are placed along a line perpendicular to the surface of the LED 5.

This improves the unintercepted illumination losses (UI) since the spheroid lens diameter is greater than the core diameter. The diameter of the spheroid lens 1 could be even greater than the fiber diameter. The spheroid lens 1 provides three-dimensional convergence of received light. This allows a substantial increase in the interception of the energy radiated from the sourc...