Electronic semiconductor control of light in optical waveguide

Details Electronic semiconductor control of light in optical waveguide Electronic semiconductor control of light in optical waveguide

2001-05-17

2004-06-08

Palmer, Phan T. H. (Department: 2874)

Optical waveguides

Temporal optical modulation within an optical waveguide

Electro-optic

C385S008000, C385S014000, C385S040000

Reexamination Certificate

active

06748125

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to optical devices, and more particularly to optical waveguide devices.
BACKGROUND OF THE INVENTION
In the integrated circuit industry, there is a continuing effort to increase device speed and increase device densities. Optical systems are a technology that promise to increase the speed and current density of the circuits. Optical devices, such as optical interconnectors, modulators, deflectors, and lenses are components in these optical systems. Such optical devices can be used to perform a variety of functions in integrated circuits such as switching or data transmission. Optical devices that perform different functions are typically formed and shaped differently in order to perform the different functions. As such, each type of optical device, and each size of the same optical device type, has to be manufactured distinctly. Therefore, the production of precision optical devices is expensive.
Additionally, passive optical waveguide devices are susceptible to changes in temperature, contact, pressure, humidity, etc. As such, the optical devices are typically contained in packaging that maintains the conditions under which the optical devices are operating. Providing such packaging is extremely expensive. Even if such packaging is provided, passive optical devices may be exposed to slight condition changes. As such, the passive optical devices perform differently under the different conditions. For example, the modulators will modulate the light a different amount and the optical deflectors will deflect the light to a different angle, etc. If the characteristics of a passive optical device is changed outside of very close tolerances, then the optical device will not adequately perform its function. In other words, there is no adjustability to the passive optical devices.
It would therefore be desirable to provide an optical device that can be produced using more uniform components while providing a wide range of functionality. Additionally, it would be desired to provide an active optical device whose operation can be adjusted by slight modification to the structure of the device.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus and associated method for changing the effective mode index or the propagation constant in a region of changeable propagation constant in a waveguide. The method comprises changing the free-carrier distribution in the semiconductor waveguide. This is accomplished by using the same semiconductor waveguide as part of a Field Effect Transistor (FET) of Metal Oxide Silicon capacitor (MOSCAP) with at least one electrode in contact with the semiconductor and the other electrode of a prescribed electrode shape proximate to the waveguide separated by an electrical insulator. Application of the voltage between the electrodes leads to a changeable propagation constant and an changed effective mode index in a region of changeable propagation constant in the waveguide due to the changes in the free-carrier distribution. This change in local level of effective mode index propagation constant in a region of changeable propagation constant roughly corresponds, in shape, to the shaped electrode. Thus, the effective mode index or the propagation constant in the region of changeable propagation constant in the waveguide is controlled by application of the voltage to the shaped electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.
FIG. 1
shows a front cross sectional view of one embodiment of an optical waveguide device including a field effect transistor (FET);
FIG. 2
shows a top view of the optical waveguide device shown in
FIG. 1
;
FIG. 3
shows a section view as taken through sectional lines
3
—
3
of
FIG. 2
;
FIG. 4
shows a front cross sectional view of one embodiment of an optical waveguide device including a metal oxide semiconductor capacitor (MOSCAP);
FIG. 5
shows a front view of another embodiment of an optical waveguide device including a high electron mobility transistor (HEMT);
FIG. 6
shows a graph plotting surface charge density and the phase shift, both as a function of the surface potential;
FIG. 7
shows one embodiment of a method to compensate for variations in temperature, or other such parameters, in an optical waveguide device;
FIG. 8
shows another embodiment of a method to compensate for variations in temperature, or other such parameters, in an optical waveguide device;
FIG. 9
shows a top view of another embodiment of optical waveguide device
100
;
FIG. 10
shows a side cross sectional view of one embodiment of a ridge optical channel waveguide device;
FIG. 11
shows a side cross sectional view of one embodiment of a trench optical channel waveguide device;
FIG. 12
shows one embodiment of a wave passing though a dielectric slab waveguide;
FIG. 13
shows a top view of another embodiment of an optical waveguide device from that shown in
FIG. 2
, including one embodiment of a prism-shaped gate array that provides for light deflection by the optical device;
FIG. 14
shows a top cross sectional view of the waveguide of the embodiment of prism-shaped gate array of
FIG. 13
including dotted lines representing a region of changeable propagation constant. The solid light rays are shown passing through the regions of changeable propagation constant corresponding to the prism-shaped gate array;
FIG. 15
, including
FIGS. 15A
,
15
B,
15
C and
15
D, show side cross section views of the optical waveguide device of
FIG. 13
or taken through sectional lines
15
—
15
in
FIG. 13
,
FIG. 15A
shows both gate electrodes
1304
,
1306
being deactivated,
FIG. 15B
shows the gate electrode
1304
being actuated as the gate electrode
1306
is deactivated,
FIG. 15C
shows the gate electrode
1304
being deactuated as the gate electrode
1306
is activated, and
FIG. 15D
shows both gate electrodes
1304
and
1306
being actuated;
FIG. 16
shows a top view of another embodiment of an optical waveguide device that is similar in structure to the optical waveguide device shown in
FIG. 2
, with a second voltage source applied from the source electrode to the drain electrode, the gate electrode and electrical insulator is shown partially broken away to indicate the route of an optical wave passing through the waveguide that is deflected from its original path along a variety of paths by application of voltage between the source electrode and gate electrode;
FIG. 17
shows another embodiment of an optical deflector;
FIG. 18
shows a top view of one embodiment of an optical switch that includes a plurality of the optical deflectors of the embodiments shown in
FIGS. 14
,
15
, or
16
;
FIG. 19
shows a top view of another embodiment of an optical switch device from that shown in
FIG. 18
, that may include one embodiment of the optical deflectors shown in
FIGS. 14
,
15
, or
16
;
FIG. 20
shows one embodiment of a Bragg grating formed in one of the optical waveguide devices shown in
FIGS. 1-3
and
5
;
FIG. 21
shows another embodiment of a Bragg grating formed in one of the optical waveguide devices shown in
FIGS. 1-3
and
5
;
FIG. 22
shows yet another embodiment of a Bragg grating formed in one of the optical waveguide devices shown in
FIGS. 1-3
and
5
;
FIG. 23
shows one embodiment of a waveguide having a Bragg grating of the type shown in
FIGS. 20
to
22
showing a light ray passing through the optical waveguide device, and the passage of reflected light refracting off the Bragg grating;
FIG. 24
shows an optical waveguide device including a plurality of Bragg gratings of the type shown in
FIGS. 20
to
22
, where the Bragg gratings are arranged in series;
FIG. 25
, which is shown exploded in
FIG. 25B
, shows a respective top view and top exploded view of another embodiment o

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