FLU1D1C OPTICAL SWITCHING ELEMENTS
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to optical signal components, and more particularly to optical signal switching components.
2. Technical Background Fiber optic systems use a large number of switches to route signals. Previous optical switches typically rely on moving fibers, prisms, and mirrors to perform the switching operation. However, the moving of a physical component to do the switching gradually deteriorates the physical component overtime to the point where the switch no longer can
properly function.
A deteriorated component necessitates replacement of the switch.
The large number of switches further exacerbates the replacement issue,
and increases the cost of maintaining the operation of the fiber optic
system.
SUMMARY OF THE INVENTION
The present invention overcomes this disadvantage as well as other disadvantages. In accordance with the teachings of the present invention, an apparatus for switching an optical signal via an optical switch is disclosed. The optical switch includes an input point through which the optical signal enters the optical switch. The optical signal exits the optical switch through a first exit point. The optical switch includes a cavity that is connected to the input point and to the exit point. A fluid is disposed in the cavity for controlling whether the optical signal exits through the first
exit point.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described in the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description
and the following detailed description are merely exemplary of the invention, and are intended to provide an overview of framework for understanding the nature and character of the invention as it is claimed.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various features and embodiments of the invention, and together with the description serve to
explain the principles and operation of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram depicting a two exit point switching embodiment of the present invention;
Figure 2 is a flow chart depicting the steps associated with operation of the optical switch of the embodiment in Figure 1 ;
Figure 3 is a block diagram depicting the optical switch of the present invention containing one or more optical signal exit points;
Figure 4 is a block diagram depicting the optical switch of the present invention using multiple fluids for switching an optical signal; Figure 5 is a block diagram depicting the present invention mixing two or more fluids in order to switch an optical signal; and
Figures 6 and 7 are schematic diagrams depicting the present invention having different cavity geometric configurations that are used to
switch multiple input optical signals.
DETAILED DESCRIPTION THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference
numerals are used throughout the drawings to refer to the same or like parts.
Figure 1 depicts a non-limiting example of an optical switch 20 of the present invention. Optical switch 20 includes an input guide or fiber
22 to allow an optical signal 24 to enter the switch. Optical signal 24 exits optical switch 20 through either a first exit guide or fiber 26 or through a second guide or fiber 28.
Fluid 30 is pumped into cavity 32 in order to control whether the input optical signal 24 exits through exit point 26 or 28. When cavity 32 does not contain fluid 30, the glass/air boundary 34 of cavity 32 reflects optical signal 24 to follow path 36 to second exit point 28.
However, when cavity 32 is filled with fluid 30, input optical signal 24 follows path 38 to first exit point 26. Optical signal 24 travels through cavity 32 to first exit point 26 since the fluid in cavity 32 matches (or at least substantially matches) the refractive index of the material used to
form cavity 32. Accordingly, optical signal 24 passes through cavity 32 without being reflected by boundary 34. The present invention also functions as a latch since the state of the switch is maintained until it
receives a control signal to change state. Thus, constant energy is not required to maintain the state of the switch.
Preferably, fluid 30 is pumped into and out of cavity 32 via pump 40. Pump 40 utilizes conduits 42 and 44 to pump via electrophoresis the fluid into and out of cavity 32.
Fluid 30 includes using either liquids or gases that when placed in cavity 32 affect the path of input optical signal 24 so as to perform a predetermined switching function. A low index or high index of refraction fluid (such as a liquid or a gas) is preferably used to maximize the contact with the glass of cavity 32.
Cavity 32 preferably is formed via chemical etching of glass and includes an AR (anti-reflection) coating at boundary 34. One example of the size of cavity 32 is a cavity that is approximately 8,000 cubic nanometers in volume (i.e., 20 x 20 x 20 nanometers) for a single mode waveguide. For a multimode waveguide, a non-limiting example of the size of cavity 32 is 100,000 cubic nanometers. It should be understood that these cavity sizes are only examples and vary based upon the optical switching application at hand. Fibers or light guides are preferably aligned with the cavity at an angle appropriate to optimize coupling. Pump 40 pumps fluid 30 into and out of cavity 32 based upon a
control signal 46 that is indicative of whether optical signal 24 should exit through first exit point 26 or second exit point 28. Pump 40 uses an
electro-osmotic or electro hydrodynamic pump to move the fluid into and
out of cavity 32. In a preferred embodiment, pump 40 fills or empties cavity 32 within a time range of one to fifty milliseconds. However, in the preferred embodiment, pump 40 performs the pumping function within a
time range of one to twenty milliseconds.
Figure 2 depicts process steps associated with the operation of the optical switch of Figure 1. With reference to Figure 2, start indication block 60. indicates that at process block 62, the optical switch receives the optical signal. Decision block 64 determines (preferably via a control signal) which exit point of the switch should receive the input optical signal. If the first exit point is desired, processing continues at decision block 66 which determines whether the cavity of the optical switch is filled with fluid. If the cavity is filled with fluid, then processing continues at process block 68 wherein the optical signal passes through the cavity to the first exit point before processing ends at end block 70. If decision block 66 determines that the cavity is not filled with fluid, process block 72 fills the cavity with fluid before process block 68 is performed.
If the received optical signal is to pass to the second exit point as determined by decision block 64, then decision block 80 determines
whether the cavity is filled with fluid. If the cavity is not filled with fluid, the received optical signal is routed by the cavity (preferably via reflection) to the second exit point at process block 82. If the cavity is filled as
determined by decision block 80, then process block 84 empties the cavity
of fluid before process block 82 is performed. Processing terminates at end block 70.
Figure 3 depicts a block diagram of optical switch 20. Figure 3 depicts an embodiment of the present invention wherein the present invention contains only a single optical signal exit point 100. Depending on whether cavity 32 contains fluid, optical signal input either traverses cavity 32 to first optical signal exit point 100 or does not reach exit point 100. Thus, in this embodiment of the present invention, the present invention operates as an open or closed optical circuit component.
In another embodiment of the present invention, cavity 32 is configured to not only route a received optical signal to first optical signal exit point 100 but also includes routing the signal to one or more additional optical signal exit points as shown by reference numeral 102. In this manner, the present invention operates as a multiple exit point optical switch. Also, the present invention can accept multiple optical signal input signals as depicted by reference numeral 103.
In the preferred embodiment, fluid 30 is stored in a fluid storage compartment 104. Fluid delivery system 106 delivers fluid from
compartment 104 to cavity 32.
Cavity 32 includes a fluid exit point 108 so that fluid 30 may leave
the cavity. Upon leaving cavity 32, fluid 30 can either be disposed of or recycled back into compartment 104.
Figure 4 depicts another embodiment of the present invention
wherein multiple fluids 120 are delivered to cavity 32. Each of the fluids
120 in this embodiment are pumped separately from the other fluids into cavity 32. When cavity 32 is to be emptied, the fluid is returned via fluid exit point 108 back to the correct fluid storage compartment.
Through use of multiple fluids within a single optical switching device 20, different switching functions can be achieved. For example, the fluids can contain different index of refractions in order to pass a received optical signal to a different exit point.
Figure 5 is still another embodiment of the present invention wherein multiple fluids 120 can be mixed with one or more other fluids at mixer 130 before being delivered to cavity 32. For example, a first fluid and a second fluid can be mixed by mixer 130 in order to achieve a different index of refraction. The mixing of the fluids produces a fluid whose index of refraction is an average of the index of refraction for the first and second fluids. Mixer 130 preferably mixes two or more fluids in various ratios to produce a desired index of refraction. If cavity 32 is to be filled with fluid that is not to be mixed with another fluid, then the fluid is delivered directly to cavity 32 thereby bypassing mixer 130. The mixed
fluid preferably exits fluid exit point 108 such that it is not recycled back
into one of the compartments 120.
Figure 6 depicts an alternate embodiment of the present invention that uses different cavity geometric configurations to switch multiple input optical signals. For example, switch 20 in this embodiment is a 4x4 switch. Switch 20 can receive input optical signals 160, 162, 164, and 166, and can route these input signals to different exit points of the switch by filling with fluid the different cavities (150, 152, 154, and 156) located within switch 20. Figure 7 depicts a non-limiting example of the routing in this embodiment associated with input optical signal 160. Input optical signal 160 follows exit path 170 when cavities 150 and 152 are filled with fluid. Input optical signal 160 follows exit path 172 when cavities 150 and 154 are filled with fluid but cavity 152 is not filled with fluid. Input optical signal 160 follows exit path 174 when cavities 150 and 156 are filled with fluid but cavities 152 and 154 are not filled with fluid. Input optical signal 160 follows exit path 176 when cavity 150 is filled with fluid but cavities 152, 154, and 156 are not filled with fluid.
Switch 20 performs similar routing for the other input optical signals 162, 164, and 166. It should be further understood that the present
invention is not limited to the geometric configuration of four inputs and
outputs, but includes other geometric configurations to handle the
application at hand.
It will be apparent to those skilled in the art that various modifications and adaptations can be made to the present invention
without departing from the spirit and scope of this invention. Thus, it is intended that the present invention covers the modifications and adaptations of this invention, provided that they come within the scope of the appended claims and their equivalents.