Optical waveguides – Temporal optical modulation within an optical waveguide
Reexamination Certificate
1999-04-27
2001-12-04
Font, Frank G. (Department: 2877)
Optical waveguides
Temporal optical modulation within an optical waveguide
C385S003000, C385S009000, C385S002000
Reexamination Certificate
active
06327396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an optical waveguide having a region to which interacting means, such as a dopant or electrode, are applied for controlling an optical property of the a waveguide.
2. Background of the Related Art
It is known to apply dopant to a portion of the waveguide, for instance to form a p-n or p-i-n diode across the waveguide for injecting charge carriers into the waveguide and thus altering the effective refractive index of the waveguide. By this means a phase modulator can be provided such as the phase modulator disclosed in WO95/08787. However, in designing such a device, a compromise has to be made between the desire to maximise the overlap between the charge carriers injected into the waveguide and the optical mode therein while minimising the attenuation caused by overlap between the optical mode and the doped regions.
It is also known to apply a metal layer to a waveguide, e.g. to provide an electrical contact, or a heating element thereon. Again, there is a desire to position this as close as possible to the optical mode to maximise the effect of the electrical contact and/or heating but, on the other hand, the metal layer needs to be spaced from the optical mode so as to minimise absorption of one or both of its constituent TM or TE modes by tha metal layer.
There thus remains a need to be able to apply interacting means, such as dopant or an ohmic contact, to a waveguide without the interacting means itself causing substantial perturbation, such as attenuation or polarization, of an optical wave carried by the waveguide.
SUMMARY OF THE INVENTION
The present invention aims to provide a solution to the problems associated with the related art.
Thus, according to the present invention, there is provided an optical waveguide having a first portion to which interacting means are applied to enable an optical property of a second portion of the waveguide to be altered via said interacting means, the first and second portions each being formed of a light conducting material, the first portion having a structure the geometry of which prevents an optical wave being carried thereby, whereby the interacting means can be positioned in close proximity to the second portion without the interacting means itself causing a substantial perturbation of an optical wave carried by the second portion of the waveguide.
The present invention may be achieved in whole or in part by an optical waveguide, comprising: (1) a first light conducting portion having a structure that inhibits an optical wave from propagating therein; (2) a second light conducting portion adapted to guide the optical wave; and (3) interacting means positioned on the first light conducting portion such that the interacting means can alter an optical property of the second light conducting portion, wherein the interacting means is positioned so that it does not directly and substantially perturb the optical wave when the optical wave is propagating through the second light conducting portion.
The present invention may also be achieved in whole or in part by an optical waveguide, comprising: (1) a first waveguide portion; (2) a light guiding region within the first waveguide portion; (3) a second waveguide portion that inhibits light from propagating therein; and (4) a modulator having at least a portion that is positioned on or in the second waveguide portion, wherein the first waveguide portion, the second waveguide portion and the modulator are arranged such that the modulator can modulate an optical property of the light guiding region and such that, when light is guided by the light guiding region, the guided light is not substantially perturbed by the modulator.
The present invention may also be achieved in whole or in part by an optical waveguide comprising: (1) a silicon substrate; (2) an insulating layer on the silicon substrate; (3) a silicon layer on the insulating layer shaped into a first waveguide portion and a second waveguide portion, wherein the second waveguide portion is adapted to inhibit light from propagating therein; (4) a light guiding region within the first waveguide portion; and (5) a modulator having at least a portion that is positioned on or in the second waveguide portion, wherein the first waveguide portion, the second waveguide portion and the modulator are arranged such that the modulator can modulate an optical property of the light guiding region and such that, when light is guided by the light guiding region, the guided light is not substantially perturbed by the modulator.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
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patent: 5617493 (1997-04-01), Nishimto
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patent: 5908305 (2000-04-01), Crampton et al.
patent: 0 433 552 A2 (1991-06-01), None
patent: 2161027 (1986-01-01), None
Udd, Eric, “Fiber Optic Sensors: An Introduction for Engineers and Scientists, ” John Wiley & Sons, Inc., 1991, pp. 134-135.
Bookham Technology plc
Fleshner & Kim LLP
Font Frank G.
Nguyen Sang H.
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