Optical waveguides – Temporal optical modulation within an optical waveguide – Electro-optic
Reexamination Certificate
2001-09-14
2004-03-09
Lee, John D. (Department: 2874)
Optical waveguides
Temporal optical modulation within an optical waveguide
Electro-optic
C385S132000, C385S142000, C385S008000
Reexamination Certificate
active
06704468
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to an optical communications system and, more specifically, to an optoelectronic device and a method of manufacture therefor.
BACKGROUND OF THE INVENTION
Certain types of waveguide based optical switches, also referred to as optical modulators, are commonly used in today's optical communications systems. An optical modulator is generally known as a device that modulates or varies an amplitude of an optical signal passing therethrough. Such optical modulators have many different uses in today's optical communications systems. For example, high-speed optical modulators are used to encode information into an optical signal generated by an optical source, such as an optical laser, where the information is represented by changes in the amplitude of the optical signal. Additionally, low-speed optical modulators (also referred to as optical attenuators), may be used in conjunction with an optical amplifier to control the overall gain of an amplifier stage. This is generally used to account for gradual changes in a received optical signal, for example, as an optical source ages.
There is currently a desire to provide optical modulators that have both high throughput and low driving voltage. A problem arises in that high throughput and low driving voltage are not mutually exclusive. For example, increasing the throughput requires matching a mode size of a waveguide of the optical modulator with a spot size of a fiber being coupled to the optical modulator. Increasing the mode size of the waveguide to improve throughput causes an electric field associated with the waveguide to diverge, thus, requiring a higher driving voltage to operate the optical modulator. Additionally, reducing the driving voltage of the optical modulator requires reducing the size of the waveguide mode, however, such a design choice causes the throughput of the device to decrease because the spot size of the fiber no longer matches the mode size of the waveguide.
Prior art devices attempted to optimize the overall performance of the optical modulator (given the non mutual exclusive nature of the optical throughput and drive voltage) by sacrificing a portion of the optical throughput to achieve a lower device voltage, or sacrificing a little higher device voltage to achieve a higher optical throughput. It has been found, however, that such a design produces an inefficient optical modulator that does not attain the stringent requirements of today's optical modulators.
Accordingly, what is needed in the art is an optical modulator that attains the stringent requirements of today's optical modulators and does not experience the problems experienced by the prior art optical modulators.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides an optoelectronic device, a method of manufacture therefore, or an optical communications system including the optoelectronic device. The optoelectronic device may include a substrate and a waveguide located within the substrate. Additionally, the waveguide may include a first portion having a width, depth, and refractive index, and a second portion having a different width, depth and refractive index.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.
REFERENCES:
patent: 4865407 (1989-09-01), Suzuki et al.
patent: 6067387 (2000-05-01), Oh et al.
patent: 2002/0118916 (2002-08-01), Lee et al.
Agere Systems Inc.
Lee John D.
Song Sarah U
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