US20230324608A1 - Optical switch having latched switch states and associated methods - Google Patents
Optical switch having latched switch states and associated methods Download PDFInfo
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- US20230324608A1 US20230324608A1 US17/658,829 US202217658829A US2023324608A1 US 20230324608 A1 US20230324608 A1 US 20230324608A1 US 202217658829 A US202217658829 A US 202217658829A US 2023324608 A1 US2023324608 A1 US 2023324608A1
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Images
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/0147—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on thermo-optic effects
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/1228—Tapered waveguides, e.g. integrated spot-size transformers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3536—Optical coupling means having switching means involving evanescent coupling variation, e.g. by a moving element such as a membrane which changes the effective refractive index
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
- G02B6/358—Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
- G02F1/31—Digital deflection, i.e. optical switching
- G02F1/313—Digital deflection, i.e. optical switching in an optical waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12035—Materials
- G02B2006/12038—Glass (SiO2 based materials)
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12133—Functions
- G02B2006/12145—Switch
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12166—Manufacturing methods
- G02B2006/12195—Tapering
Definitions
- optical materials that can vary their refractive index and maintain a set index of refraction without using an outside power source for continuous latching.
- Many optical devices thus employ polarizable materials such as liquid crystals, lithium niobate (LiNbO 3 ) materials, or piezo-optic materials. Devices made from these materials are typically slow and may be anisotropic and birefringent, thus making them polarization dependent and non-latching.
- Most electric field or optically switched materials have a relatively small index change of less than about 0.01, or are orders of magnitude smaller.
- An electrically conductive layer may be on at least one of the plurality of optical fibers and electrically coupled to the PCM layer to selectively change the phase of the PCM layer.
- a heat source may be thermally coupled to the PCM layer to selectively change the phase of the PCM layer.
- the at least one PCM layer may comprise first and second PCM layers on opposite sides of the optical switching portion.
- Each of the plurality of optical fibers may comprise a single mode optical fiber.
- the PCM layer may comprise a chalcogenide.
- the optical switches may be configured into an array, for example.
- Another aspect is directed to a method for making an optical switch having a plurality of latched switch states.
- the method may comprise laterally joining together a plurality of optical fibers to define an optical switching portion, and forming at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
- PCM phase change material
- FIG. 1 is a schematic sectional view of an optical switch having a phase change material (PCM) layer where its phase determines a latched switch state according to the invention.
- PCM phase change material
- FIG. 14 is a graph showing an example of the low refractive index and large index variation of a PCM layer using a chalcogenide glass as germanium and selenium in a specific stoichiometric ratio (Ge 30 Se 70 ).
- This optically transparent chalcogenide glass may have a general formulation and stoichiometry of Ge x Se 100-x within the range as noted above.
- This material as the PCM layer 32 may provide changes in a large index of refraction greater than 10%, but remain in a given latched state indefinitely.
- the PCM layer 32 takes advantage of the thermally induced structural phase changes to vary the index of refraction, which is switchable and reversible, and remains latched in a given state once switched. It is low-loss in the telecom wavelengths in both states.
- an electrical source 42 and a conductive layer 40 ( FIG. 8 ) on at least one of the plurality of optical fibers 24 and electrically coupled to the PCM layer 32 to selectively change the phase of the PCM layer at the optical switch 20 .
- the optical fiber 24 in this example the drop or second optical fiber 24 b , is coated with an electrically conductive layer 40 such as gold at about a few microns thickness such as about 2-3 microns as a non-limiting example.
- the distance along the optical fiber 24 b to which the PCM layer 32 will be applied may have its electrically conductive layer 40 removed, and the PCM layer applied such as by various coating technologies. That optical fiber 24 b section having the electrically conductive layer 40 removed and the PCM layer 32 applied, is joined laterally with another optical fiber, in this example, the first optical fiber 24 a , to form the optical device as an optical switch 20 shown in FIG. 8 .
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
An optical switch has latched switch states and includes optical fibers that are laterally joined together to define an optical switching portion. At least one phase change material (PCM) layer is on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the latched switch states.
Description
- The present invention relates to the field of optics, and, more particularly, to optical switches and related methods.
- Optical systems regularly use active devices to control or switch optical power or signals on demand. Currently, there are few optical materials available to switch optical devices and maintain a latched state. Instead, many optical devices rely on a continuous power control, such as an optical signal or a thermal, electrical, or mechanical force to maintain the optical device in a desired configuration. Most available materials used in optical devices and associated switches are considered “non-latching.” Examples include non-linear optical devices such as liquid crystals that may react to changes in electric fields, thermo-optic devices that may react to changes in temperature, and piezo-optic devices that may react to changes in mechanical strain. Many conventional non-latching optical switching devices use an optical signal for control and function as non-linear optics under intense laser power.
- Some optical switches are formed from discrete optical and electronic components, or are formed as photonic integrated circuit (PIC) structures based on semiconductor wafer fabrication processes. Discrete optical switches tend to be large, and use a separate electrical power source to operate. For a PIC, a large power penalty occurs going from the optical fiber into the PIC and back out of the PIC into another optical fiber. These losses may be greater than one decibel.
- There are few optical materials that can vary their refractive index and maintain a set index of refraction without using an outside power source for continuous latching. Many optical devices thus employ polarizable materials such as liquid crystals, lithium niobate (LiNbO3) materials, or piezo-optic materials. Devices made from these materials are typically slow and may be anisotropic and birefringent, thus making them polarization dependent and non-latching. Most electric field or optically switched materials have a relatively small index change of less than about 0.01, or are orders of magnitude smaller.
- Some optical devices employ chalcogenides for an X3 photo refractive effect, but not for the optical benefits of a phase change. Those chalcogenides used for their phase change properties are commonly used in electronic or optical memories and have not been reliable as an active optical material due to absorption or large index values. Other optical devices may couple chalcogenide materials with mechanical mechanisms, such as an actuator, or a microelectromechanical device, but these optical devices are limited because of their use of an external actuator or MEMS device.
- In general, an optical switch having a plurality of latched switch states may comprise a plurality of optical fibers laterally joined together to define an optical switching portion, and at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
- The plurality of latched switch states may correspond to a plurality of different continuous optical fiber signal paths. The optical switching portion may have a tapered diameter shape. At least one of the plurality of optical fibers may be configured to supply optical energy to the optical switching portion to selectively change the phase of the PCM layer. An optical energy source may be coupled to the at least one of the plurality of optical fibers and operable at a different wavelength for heating than a wavelength for signal transmission.
- An electrically conductive layer may be on at least one of the plurality of optical fibers and electrically coupled to the PCM layer to selectively change the phase of the PCM layer. A heat source may be thermally coupled to the PCM layer to selectively change the phase of the PCM layer. The at least one PCM layer may comprise first and second PCM layers on opposite sides of the optical switching portion. Each of the plurality of optical fibers may comprise a single mode optical fiber. The PCM layer may comprise a chalcogenide.
- The optical switches may be configured into an array, for example. Another aspect is directed to a method for making an optical switch having a plurality of latched switch states. The method may comprise laterally joining together a plurality of optical fibers to define an optical switching portion, and forming at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
- Other objects, features and advantages of the present invention will become apparent from the detailed description of the invention which follows, when considered in light of the accompanying drawings in which:
-
FIG. 1 is a schematic sectional view of an optical switch having a phase change material (PCM) layer where its phase determines a latched switch state according to the invention. -
FIG. 2 is another schematic sectional view of the optical switch ofFIG. 1 showing its switched state. -
FIG. 3 is a sectional view of an example optical fiber ofFIGS. 1 and 2 showing the PCM layer. -
FIG. 4 is an image of the optical fiber ofFIG. 3 showing an optical mode field within the central portion of the optical fiber. -
FIG. 5 is another image of the optical fiber similar toFIG. 4 where the changed phase of the PCM layer moves the mode field to an upper region to implement a latched switch state. -
FIG. 6 is another schematic sectional view of the optical switch showing an optical energy source coupled to an optical fiber. -
FIG. 7 is a graphical view of multiple optical fibers showing different exposures created by optical energy that determines a phase change. -
FIG. 8 is another schematic sectional view of the optical switch showing an electrically conductive layer on an optical fiber and electrically coupled to the PCM layer. -
FIG. 9 is a graph showing the results of an electrically induced change in the PCM layer ofFIG. 8 . -
FIG. 10 is another schematic sectional view of the optical switch showing a heat source thermally coupled to the PCM layer. -
FIG. 11 is another schematic sectional view of the optical switch showing first and second PCM layers on opposite sides of the optical switching portion. -
FIG. 12 is another schematic sectional view of an optical device, such as an optical switch, showing four optical fibers and first and second PCM layers. -
FIG. 13 is a schematic representation of an optical switching device having optical switches arranged in an array. -
FIG. 14 is a graph showing an example of the low refractive index and large index variation of a PCM layer using a chalcogenide glass as germanium and selenium in a specific stoichiometric ratio (Ge30Se70). -
FIG. 15 is a high-level flowchart illustrating an example method of making an optical device as an optical switch as shown inFIG. 1 having a PCM layer. - The present description is made with reference to the accompanying drawings, in which exemplary embodiments are shown. However, many different embodiments may be used, and thus, the description should not be construed as limited to the particular embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in different embodiments.
- Referring now to
FIGS. 1 and 2 , there is illustrated generally at 20, an optical device formed in this example as an optical switch having a plurality of latched switch states. A plurality ofoptical fibers 24 are laterally joined together to define anoptical switching portion 28, and in this example formed as a tapered diameter shape. Although any number of optical fibers may be employed, in the example shown inFIGS. 1 and 2 , twooptical fibers optical fiber 24 a being a through fiber through which an initial optical signal is transmitted (FIG. 1 ), and a secondoptical fiber 24 b acting as the drop fiber to which the optical signal may be switched via acontrol signal 30 such as an optical pulse (FIG. 2 ). - At least one phase change material (PCM)
layer 32 is formed on theoptical switching portion 28. The phase of the PCM layer may determine a latched switch state from among the plurality of latched switch states, which may be changed by application of heat from aheat source 33 as explained further below such as generated from an optical, thermal or electrical energy source. As best illustrated in the change of the optical signal path from theoptical switch 20 shown inFIG. 1 to that shown inFIG. 2 , the plurality of latched switch states corresponds to a plurality of different continuous optical fiber signal paths, and in this example, changing from the through or firstoptical fiber 24 a into the secondoptical fiber 24 b, also termed the drop fiber through which thecontrol signal 30 passes. - The end views of the
optical switch 20 inFIGS. 1 and 2 are illustrated at the right and show in the through state ofFIG. 1 the optical signal passing through the firstoptical fiber 24 a shown by the “plus” sign on the right. The switched state is shown inFIG. 2 , and the phase of thePCM layer 32 changes the latched state so that the optical signal passes from the through or firstoptical fiber 24 a into the drop or secondoptical fiber 24 b as shown by the plus sign in the second fiber ofFIG. 2 . ThePCM layer 32 in the end view ofFIG. 2 includes hash lines indicating a phase change. In this example, thecontrol signal 30, as a separate optical signal, supplies optical energy to theoptical switching portion 28, which may be a different wavelength for heating than a wavelength for signal transmission. For example, a wavelength below approximately 700 nm, where the PCM starts to significantly absorb light, may be optimum for thermal processes to initiate a phase change created by thermal heat in thePCM layer 32. A wavelength between about 700 nm and 430 nm is possible. The long wavelength limit is defined by the onset of absorption of the light by the PCM and the lower wavelength limit is defined by the transmission or absorption of the transporting waveguide, the example here being SiO2 glass fiber. - As a non-limiting example, either one of the first and second
optical fibers optical switching portion 28 to selectively change the phase of thePCM layer 32. An optical energy source 34 (FIG. 6 ), such as a laser or other source of optical energy, may be coupled to at least one of the plurality ofoptical fibers 24 and operable at a different wavelength for heating than a wavelength for signal transmission. In the example shown inFIG. 6 , theoptical energy source 34 is coupled to the secondoptical fiber 24 b as the drop fiber. - Each of the plurality of
optical fibers 24 may be formed as a single mode optical fiber, but depending on the end use requirements, one or more of the optical fibers may be formed as a multimodal optical fiber. In this example, thecontrol signal 30 provides the optical energy, and resultant heat, to change the phase of thePCM layer 32 that is formed on one side of theoptical switching portion 28 forming theoptical switch 20. As a result, the optical phase matching condition of this optical device as anoptical switch 20 is altered and the optical signal switches from the firstoptical fiber 24 a to the secondoptical fiber 24 b. Once switched, the control signal in this example as the light from the optical energy source 34 (FIG. 6 ) is removed and the optical device, in this example theoptical switch 20, remains latched until the process is reversed. - The
PCM layer 32 is preferably formed from a chalcogenide as a chemical compound and includes a sulfide, selenide, telluride, or polonide. It is a material that when in the correct stoichiometry range is transparent at optical telecommunication wavelengths, such as a wavelength range of 1,260 nm to 1,625 nm, and in an example, the commercially well-known 1,300 and 1,550 nanometer bands, although wavelengths as low as about 850 nm are possible. ThePCM layer 32 may switch variably between two index values using electrical, thermal, or optical energy. The phase changes may occur between the temperatures giving a full molten state and temperatures giving crystallization. This material as thePCM layer 32 latches and remains in a given state upon removal of power, and has a much lower index of refraction than the more conventional phase change materials used with electronic or optical memories, for example. This material as thePCM layer 32 is more readily configured into optical devices that use traditional optical materials with low index values, such as the illustratedoptical switch 20. - This optically transparent chalcogenide glass may have a general formulation and stoichiometry of Gex Se100-x within the range as noted above. This material as the
PCM layer 32 may provide changes in a large index of refraction greater than 10%, but remain in a given latched state indefinitely. ThePCM layer 32 takes advantage of the thermally induced structural phase changes to vary the index of refraction, which is switchable and reversible, and remains latched in a given state once switched. It is low-loss in the telecom wavelengths in both states. - Referring again to
FIG. 3 , thePCM layer 32 may be formed on about half of anoptical fiber 24, in this example, about 50% of the optical fiber by directionally coating the PCM material onto the optical fiber, which in the illustrated example ofFIGS. 1 and 2 is the secondoptical fiber 24 b. ThePCM layer 32 may be coated for length of about 0.1 to 20 millimeters along the length of theoptical fiber 24 b at a depth of a few nanometers thickness, and in a non-limiting example, about no greater than 40 nm to prevent the PCM layer from becoming a waveguide itself. - As shown in the image of
FIG. 4 , with the representation distance in micrometers on both the vertical and horizontal axis, theoptical fiber 24 is shown having an optical mode field in the central portion of the optical fiber with an N of about 2.4. In the image ofFIG. 5 , the change in phase of thePCM layer 32 with an N of about 2.7 moves the mode field to an upper region of only a few micrometers in theoptical fiber 24 to implement a latched switch state. The sectional, schematic view inFIG. 7 of multipleoptical fibers 24 illustrates different exposures created by the optical energy from an optical energy source 34 (FIG. 6 ) that induces a phase change. The schematic views inFIG. 7 show alternating bright, dark, bright exposures that allow switching back and forth in theoptical switch 20 between different latched switch states. - It is also possible to include an
electrical source 42 and a conductive layer 40 (FIG. 8 ) on at least one of the plurality ofoptical fibers 24 and electrically coupled to thePCM layer 32 to selectively change the phase of the PCM layer at theoptical switch 20. As illustrated, theoptical fiber 24, in this example the drop or secondoptical fiber 24 b, is coated with an electricallyconductive layer 40 such as gold at about a few microns thickness such as about 2-3 microns as a non-limiting example. The distance along theoptical fiber 24 b to which thePCM layer 32 will be applied may have its electricallyconductive layer 40 removed, and the PCM layer applied such as by various coating technologies. Thatoptical fiber 24 b section having the electricallyconductive layer 40 removed and thePCM layer 32 applied, is joined laterally with another optical fiber, in this example, the firstoptical fiber 24 a, to form the optical device as anoptical switch 20 shown inFIG. 8 . - An example for the electrically induced phase change as imparted by an electrical signal directed along the electrically
conductive layer 40 into thePCM layer 32 is shown by the graph ofFIG. 9 , where the current in amperes is shown on the vertical axis and the switch cycle for the latched switch state changes back-and-forth in 7 cycles, shown on the horizontal axis. The graph shows that ohmic heating from an electrical current is able to change the phase of thePCM layer 32. - In another example, a
heat source 44 may be thermally coupled to thePCM layer 32 to selectively change the phase of the PCM layer as shown in the example of theoptical switch 20 inFIG. 10 . Athermal heat controller 46 connected to theheat source 44 controls thermal heating onto thePCM layer 32. The heat may be generated for only a few nanoseconds, for example, from 1 or 2 nanoseconds up to 10's of nanoseconds, to create the phase change. - It is also possible that the
PCM layer 32 may be formed as first and second PCM layers 32 a,32 b on opposite sides of theoptical switching portion 28 as shown inFIG. 11 . Each of the PCM layers 32 a, 32 b may be used to determine a latched switch state by applying heat via an optical signal into the respectiveoptical fiber optical energy source 34, such as inFIG. 6 , or an electrical signal applied via an electricallyconductive layer 40 such as inFIG. 8 , or aseparate heat source 44 as inFIG. 10 . - In an embodiment shown in
FIG. 12 , theoptical switch 20′ includes fouroptical fibers 24 a′, 24 b′, 24 c′, 24 d′ and first and second PCM layers 32 a′, 32 b′ are on opposite sides of theoptical switching portion 28′ formed from the tapered area of the four optical fibers. An optical input to theoptical switch 20′ may include two separate optical signal inputs, with a first optical signal enteringoptical fiber 24 b′, and the second optical signal enteringoptical fiber 24 c′. These may be selectively switched into two different outputs as two different signal paths. Theoptical control signal 50′ may be generated from an optical signal, electric current, or thermal heating as inFIGS. 6, 8, and 10 . - In the example of
FIG. 13 , a plurality ofoptical switches 20 are arranged in a switched array illustrated generally at 54, where eachoptical switch 20 has a plurality of latched switch states. This switchedarray 54 forms an optical device that may operate similar to a field programmable gate array (FPGA) and have oneinput 58 in this example. Eachoptical switch 20 includes aPCM layer 32 that may latch the respective optical switch into a different state using acontrol signal 60 applied at each optical switch as illustrated. Thecontrol signal 60 may be an optical signal, a thermally generated input to a heat source, or electrical power signal along conductive layer such as shown in respectiveFIGS. 6, 8 , and 10. - An
example PCM layer 32 may be formed from Ge30Se70 as noted before. The graph inFIG. 14 shows the refractive index relative to the wavelength in nanometers at different temperatures for thePCM layer 32 formed with the stoichiometry ratio Ge30Se70, ranging from 20° C. as shown by the line at A up to about 470° C. as shown by the line at F. This range between the lines at the 1,600 nanometers mark illustrates the low refractive index with a large index variation of thePCM layer 32. - An example single mode fiber may be used for the
optical fibers 24 and have about 125 micron cladding and an 8-10 micron core. When twooptical fibers optical switching portion 28 such as shown inFIGS. 1, 2, 6, 8, and 10-11 , the diameter of the optical switching portion may be reduced to about 10 microns to 40 microns with the tapered diameter shape. - Referring now to
FIG. 15 , a high-level flowchart illustrates an example of making an optical device as anoptical switch 20 and illustrated generally at 100. General steps are described first relative to the flowchart, followed by a more detailed process flow description. - The process starts (Block 102) and the phase change material (PCM)
layer 32 is formed on at least one optical fiber 24 (Block 104). ThisPCM layer 32 may comprise a chalcogenide material, and in an example, GexSey, where X is in the range of about 20-40, and Y is in the range of about 60-80. Thisoptical fiber 24 may be laterally joined with another optical fiber to define an optical switching portion 28 (Block 106). Energy may be applied to theoptical switching portion 28 to selectively change the phase of thePCM layer 32, such as using an electrically coupled conductive layer, a heat source thermally coupled to the PCM layer, or optical signal energy (Block 108). The process ends (Block 110). - As a more detailed process flow description, the process would start with the fusing of the glass and pulling a taper (very high temperatures). Then the process may include directionally coating one side of the fiber/coupler with the PCM that cannot withstand the high temperatures of the tapering process, e.g., using a fused biconical taper coupler process, which is the most prevalent in industry. Another method in line with the description would be to use polished or “D”-shaped fibers to access close to the core regions and deposit PCM on one of the faces prior to gluing the two faces together. A polished and glued coupler is not very prevalent in industry.
- This application is related to copending patent application entitled, “OPTICAL DEVICE HAVING PHASE CHANGE MATERIAL AND ASSOCIATED METHODS,” which is filed on the same date and by the same Assignee, the disclosure which is hereby incorporated by reference.
- Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
Claims (25)
1. An optical switch having a plurality of latched switch states and comprising:
a plurality of individual optical fibers having respective adjacent tapered medial portions laterally joined together to define an optical switching portion with a tapered diameter shape; and
at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
2. The optical switch of claim 1 wherein the plurality of latched switch states corresponds to a plurality of different continuous optical fiber signal paths.
3. (canceled)
4. The optical switch of claim 1 wherein at least one of the plurality of optical fibers is configured to supply optical energy to the optical switching portion to selectively change the phase of the PCM layer.
5. The optical switch of claim 4 comprising an optical energy source coupled to the at least one of the plurality of optical fibers and operable at a different wavelength for heating than a wavelength for signal transmission.
6. The optical switch of claim 1 comprising an electrically conductive layer on at least one of the plurality of optical fibers and electrically coupled to the PCM layer to selectively change the phase of the PCM layer.
7. The optical switch of claim 1 comprising a heat source thermally coupled to the PCM layer to selectively change the phase of the PCM layer.
8. The optical switch of claim 1 wherein the at least one PCM layer comprises first and second PCM layers on opposite sides of the optical switching portion.
9. The optical switch of claim 1 wherein each of the plurality of optical fibers comprises a single mode optical fiber.
10. The optical switch of claim 1 wherein the PCM layer comprises a chalcogenide.
11. An optical switching array device comprising:
a plurality of optical switches arranged in an array, each optical switch of the plurality of optical switches having a plurality of latched switch states and comprising
a plurality of individual optical fibers having respective adjacent tapered medial portions laterally joined together to define an optical switching portion with a tapered diameter shape, and
at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
12. The optical switching array device of claim 11 wherein the plurality of latched switch states corresponds to a plurality of different continuous optical fiber signal paths.
13. (canceled)
14. The optical switching array device of claim 11 wherein at least one of the plurality of optical fibers is configured to supply optical energy to the optical switching portion to selectively change the phase of the PCM layer.
15. The optical switching array device of claim 14 comprising an optical energy source coupled to the at least one of the plurality of optical fibers and operable at a different wavelength for heating than a wavelength for signal transmission.
16. The optical switching array device of claim 11 comprising an electrically conductive layer on at least one of the plurality of optical fibers and electrically coupled to the PCM layer to selectively change the phase of the PCM layer.
17. The optical switching array device of claim 11 comprising a heat source thermally coupled to the PCM layer to selectively change the phase of the PCM layer.
18. The optical switching array device of claim 11 wherein the at least one PCM layer comprises first and second PCM layers on opposite sides of the optical switching portion.
19. The optical switching array device of claim 11 wherein each of the plurality of optical fibers comprises a single mode optical fiber.
20. The optical switching array device of claim 11 wherein the PCM layer comprises a chalcogenide.
21. A method for making an optical switch having a plurality of latched switch states, the method comprising:
laterally joining together respective adjacent tapered medial portions of a plurality of individual optical fibers to define an optical switching portion having a tapered diameter shape; and
forming at least one phase change material (PCM) layer on the optical switching portion so that a phase of the PCM layer determines a latched switch state from among the plurality of latched switch states.
22. The method of claim 21 wherein the plurality of latched switch states corresponds to a plurality of different continuous optical fiber signal paths.
23. (canceled)
24. The method of claim 21 wherein each of the plurality of optical fibers comprises a single mode optical fiber.
25. The method of claim 21 wherein the PCM layer comprises a chalcogenide.
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US17/658,829 US11803011B1 (en) | 2022-04-12 | 2022-04-12 | Optical switch having latched switch states and associated methods |
EP23167254.4A EP4261603A1 (en) | 2022-04-12 | 2023-04-11 | Optical switch having latched switch states and associated methods |
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