The Post Office

John Edwin Midwinter

Clive R Day

Lynden A Jackson

A launcher for waves of selected mode in an optical dielectric waveguide having a core surrounded by cladding, in which the launcher includes a prism of refractive index greater than that of the waveguide and preferably greater than that of the core of the waveguide which is placed against the waveguide either before or alongside an outwardly tapering portion of the waveguide. Light from a laser is directed through the prism on to the waveguide to induce the waves in the waveguide. A matching fluid, which may set to a solid, improved the coupling of the prism to the waveguide. A detector of similar construction is also described, the tapering of the waveguide being inward.

Apparatus for launching or detecting waves of selected modes in an

An apparatus for drawing a dielectric optical waveguide having minimal attenuation characteristics comprises a double crucible in a closed atmosphere container with glass rod supply means and atmosphere supply means.

Drawing dielectric optical waveguides

The attenuation in a dielectric optical waveguide can be reduced by the following techniques:

The number of modes propagating as guided modes along a dielectric optical waveguide depends on the refractive index difference between core and cladding materials. By altering this difference the number of modes which are permitted to propagate may be controlled. The effective bandwidth of a dielectric optical waveguide depends on the number of modes transmitted because of group delay dispersion and hence this bandwidth may be controlled by controlling the number of propagating modes. In the case of a liquid cored dielectric optical waveguide, the difference between core and cladding refractive indices and hence the bandwidth may be controlled by controlling the temperature of the dielectric optical waveguide.

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Woodbridge, United Kingdom

John Edwin Midwinter