WO2007052053A2 - Beam steering arrangements and optical switches - Google Patents

Beam steering arrangements and optical switches Download PDF

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Publication number
WO2007052053A2
WO2007052053A2 PCT/GB2006/004123 GB2006004123W WO2007052053A2 WO 2007052053 A2 WO2007052053 A2 WO 2007052053A2 GB 2006004123 W GB2006004123 W GB 2006004123W WO 2007052053 A2 WO2007052053 A2 WO 2007052053A2
Authority
WO
WIPO (PCT)
Prior art keywords
bender
arrangement
carrier
optical
flexure
Prior art date
Application number
PCT/GB2006/004123
Other languages
French (fr)
Other versions
WO2007052053A3 (en
Inventor
Andrew Nicholas Dames
Original Assignee
Polatis Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0522535A external-priority patent/GB0522535D0/en
Priority claimed from GB0522929A external-priority patent/GB0522929D0/en
Application filed by Polatis Limited filed Critical Polatis Limited
Publication of WO2007052053A2 publication Critical patent/WO2007052053A2/en
Publication of WO2007052053A3 publication Critical patent/WO2007052053A3/en

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Classifications

    • 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
    • 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
    • G02B6/3502—Optical coupling means having switching means involving direct waveguide displacement, e.g. cantilever type waveguide displacement involving waveguide bending, or displacing an interposed waveguide between stationary waveguides
    • G02B6/3508—Lateral or transverse displacement of the whole waveguides, e.g. by varying the distance between opposed waveguide ends, or by mutual lateral displacement of opposed waveguide ends
    • 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
    • G02B6/351—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements
    • G02B6/3512—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror
    • G02B6/352—Optical coupling means having switching means involving stationary waveguides with moving interposed optical elements the optical element being reflective, e.g. mirror the reflective optical element having a shaped reflective surface, e.g. a reflective element comprising several reflective surfaces or facets that function together
    • 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
    • G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/3544—2D constellations, i.e. with switching elements and switched beams located in a plane
    • G02B6/3548—1xN switch, i.e. one input and a selectable single output of N possible outputs
    • 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
    • G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
    • G02B6/3554—3D constellations, i.e. with switching elements and switched beams located in a volume
    • G02B6/3558—1xN switch, i.e. one input and a selectable single output of N possible outputs
    • 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
    • G02B6/3568—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details characterised by the actuating force
    • G02B6/3578—Piezoelectric force
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H10N30/2042—Cantilevers, i.e. having one fixed end
    • H10N30/2045—Cantilevers, i.e. having one fixed end adapted for in-plane bending displacement
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • H10N30/204—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders
    • H10N30/2041—Beam type
    • H10N30/2042—Cantilevers, i.e. having one fixed end
    • H10N30/2046—Cantilevers, i.e. having one fixed end adapted for multi-directional bending displacement

Definitions

  • the invention relates to optical beam steering arrangements and optical switches.
  • the invention provides an optical beam steering arrangement comprising a collimator, a powered actuator for displacing an optical element; said displaceable optical element being said collimator or an optical element which is in communication with said collimator; and clamping means which is released when said actuator is powered up for displacing said optical element and which immobilises the displaced element in a displaced position on power down.
  • This configuration is particularly advantageous because it allows the displaceable optical element to be held accurately in position even when the actuator is powered down. This configuration also improves reliability and the likely longevity of the beam steering arrangement.
  • said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means against which the bender abuts on power down; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release the actuator from the abutment to facilitate displacement in lateral directions; and following lateral displacement on power down said bender abuts said abutment and immobilises the displaced bender in a displaced position.
  • This configuration is particularly advantageous because it allows a piezoelectric bender which is already incorporated into the beam steering arrangement as the primary driver of the actuation to also achieve clamping. This configuration minimises the number of components required to achieve clamping.
  • said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means; said abutment and said bender forming a jaw for immobilising a displaceable component of the arrangement; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release said component from said jaw to facilitate displacement in lateral directions; and following lateral displacement on power down said jaw closes onto said component to immobilise it in a displaced position.
  • This configuration also provides an advantageous form of clamping whilst using the piezoelectric bender itself whilst cooperating with an abutment.
  • the actuator incorporates a bender, an optical element carrier and a flexure joining said bender to said optical element carrier; and the flexure is said displaceable component located between said abutment and said bender in order to allow the bender and abutment to form a jaw for clamping the flexure.
  • This configuration is particularly advantageous because it provides a particularly secure clamping mechanism without running the risk of causing any damage to collimators or other more sensitive components.
  • said actuator incorporates at least one bender and the abutment is part of a second bender. This is particularly advantageous because it allows the thermal expansion of two benders to be particularly well matched. It may also allow a clamp gap to be isolated from any effects of bending the substrate.
  • first and second benders incorporate slots and are 1-D benders with lines of action at right angles from one another. This achieves a particularly symmetrical configuration with improved mechanical properties.
  • said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a second piezoelectric component is provided to clamp said flexure.
  • said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a magnetic element is provided to clamp said flexure.
  • the arrangement further comprises an optical element carrier; a flexure located at a further most region of said arrangement where the displacement is higher than at other regions of said arrangement; and clamping means for immobilising said flexure.
  • the invention provides an optical switch comprising at least an input port and a plurality of output ports; and a manually accessible component which when actuated displaces a displaceable arrangement which switches light originating from a selected input on a path to a selected output; characterised in that the switch has one or more of the following features:
  • Configuration (A) is particularly advantageous because it allows an operator to manually accurately control the switching from one input port to an output port. It also provides a relatively compact switch with improved positional accuracy when compared to the prior art documents.
  • this configuration further improves the compactness of the switch since both the input and output ports can be located on the same side of the switch whilst only one component is moved which allows improved repeatability, switch lifetime and speed of operation. Both of these configurations achieve these improvements without the need for external power and electronic systems and therefore preserve the simplicity of set up which is well known from connectors.
  • said slidable carrier runs on a track and a detent is provided to releasably secure said carrier in predetermined positions on said rack.
  • said detent incorporates a resilient protrusion which meets with a plurality of recesses located at said predetermined positions. This configuration is particularly advantageous in terms of repeatability and overall accuracy.
  • said beam inputting element is a collimator. This is particularly advantageous when the optical switch is a free space optical switch.
  • said beam inputting element is a reflector located on said carrier and the reflector is in communication with a fixed collimator. This configuration also achieves advantageous repeatability.
  • said beam inputting element is a refractor located on said carrier and the refractor is in communication with a fixed collimator. This also minimises the moveable components required in order to achieve accurate switching which is actuated manually.
  • said rotatable arrangement runs on a track and a detent is provided to releasably secure said rotatable arrangement in predetermined positions on said track. This allows the operation of manually switching to be accurately achieved.
  • said detent incorporates a resilient protrusion which meets with a plurality of recesses located at said predetermined positions. This configuration is particularly advantageous due to its repeatability whilst permitting manually driven actuation.
  • Figure 1 shows a beam steering arrangement in side elevation with parts in cross-section.
  • Figure 2a shows a piezoelectric bender and its drive arrangement in schematic form for achieving up/down movement and lengthening and shortening.
  • Figure 2b shows a piezoelectric bender and its drive arrangement in schematic form for achieving lateral movement and lengthening and shortening.
  • Figure 2c shows a cross-sectional view of the piezoelectric bender.
  • Figure 3a shows a perspective view of two slotted benders.
  • Figure 3b shows a side elevation view of two slotted benders.
  • Figure 4a shows a side elevation view of an arrangement where the bender displaces the fibre behind a fixed lens.
  • Figure 4b shows a side elevation view of an arrangement where the bender displaces a lens in front of a fixed fibre.
  • Figure 5a shows a manually operated periscope switch in cross-sectional view.
  • Figure 5b shows an optical operational end view of the switch of figure 5a.
  • Figure 6a shows a manually operated slider switch in plan view in a first position.
  • Figure 6b shows a manually operated slider switch in plan view in a second position.
  • Figure 1 shows a modification of a piezoelectric actuated collimator to collimator switch of the type described in GB2390910.
  • the angles of the collimators are set by moving a rear flexure 4 of a parallel flexure pair referenced 4 and 5 in figure 1 attached to each of the collimators at either end of the switch.
  • the flexures are relatively thin plates of flexible material. Flexure 4 extends between a mounting block 10 which is secured to the free extremity 101 of the piezoelectric bender 2 and flexure 4.
  • the piezoelectric bender is secured to a support 9 via a mount 1 of known kind.
  • the piezoelectric bender 2 may be a two dimensional bimorph capable of moving laterally upwards, downwards, right and left relative to the longitudinal axis of the bender. The displacement of the end of the bender may be in the X, Y and Z directions as shown in figure 2b.
  • the bender is also capable of extension if the bias voltage supplied is varied due to the symmetric source 20 and 21 of figure 2b.
  • a solid plate 8 is provided between flexure pair 4 and 5 so that when the piezoelectric bender is extended it clamps flexure 4 between the solid plate and the block. In this configuration, the solid plate forms an abutment against which the piezoelectric bender abuts to secure the flexure in position.
  • the voltage is applied to the bender so that in its unpowered state, the natural length of the piezoelectric bender is longer than the distance between its mount 1 and the plate 8 so that the flexure is locked in place.
  • the bender's length reduces permitting the bender to control the pointing angle of the collimator in the manner exemplified in GB2390910.
  • the bender locks in place in a new position. This process is helped by the lengthwise actuation speed being much faster than the left /right; up /down adjustment response time of the actuator.
  • the lengthwise resonance of the piezo is set by the velocity of sound along the length of the piezo, and is around 2OkHz compared to the left/right up/down actuator resonances which is around 200Hz.
  • Small offset errors, if any, introduced in the clamping process can, if necessary, be pre- compensated by deliberately offsetting the initial pointing angle of the collimator.
  • the result of the clamping process may be checked by energising feedback position sensors or by measuring the optical transmission, and the clamping process repeated on an individual actuator basis if needed.
  • the optical element displaced by this particular arrangement is a collimator 7 which is carried by a carrier 6.
  • the collimator 7 is joined to a fibre 3 which passes through openings provided in both flexures 4 and 5.
  • the fibre 3 may be secured to the bender through an adhesive point 102 as appropriate.
  • Figure 2A shows the manner in which a 1 D piezoelectric actuator may be driven to achieve extension and contraction as well as up and down motion.
  • Figure 2B shows the connections necessary for a 2-D piezoelectric actuator of the kind discussed with reference to figure 1.
  • Figure 2C shows the cross-section of the bender with a succession of electrode plates amongst piezoelectric material.
  • piezoelectric actuators can be utilised such as those shown in GB2378573.
  • a separate piezoelectric clamp actuator may be used for immobilising the flexure plate.
  • This piezoelectric actuator may be an extension and contraction actuator which traps the plate against an abutment of the kind shown in figure 1.
  • the invention envisages the use of a separate magnetic clamp which may close onto an otherwise mobile flexure.
  • a clamp flexure may be attached to carrier 6 or to a distal extremity 103 of the collimator in order to reduce the sensitivity to position offsets created in the clamping operation.
  • the clamp is preferably undamped when energised and arranged to permit full clamping when powered down.
  • the figures 3a and 3b show a piezoelectric actuator assembly attached to a support structure at end piece 33.
  • the left right movement is provided by a slotted bimorph 3Z joined to a similar slotted bimorph 31.
  • Bimorph 31 In the clamped state, bimorph 31 is unbiased and abuts into end piece 33.
  • Bimorph 32 can either be always unbiased or for greater relative clamping displacement at the expense of having to maintain a voltage in the clamped state, it can be unbiased during movement and biased in the clamped state.
  • a collimator 7 employs two flexures 44 and 45 to secure respectively to end piece 33 and bimorph 31 enabling angle adjustment of the collimator in both axes when free and locked in angle when clamped. This structure has the advantage that the thermal expansion of the two piezoelectric elements is well matched and the clamp gap is isolated from any effects of bending the substrate.
  • the piezoelectric actuator 31 can be replaced by a 2D bimorph and piezoelectric actuator 31 by a passive piezoelectric strut.
  • piezoelectric actuator 32 can be a 2 D bimorph and piezoelectric actuator 31 can be an extension plate, biased when free, and unbiased when clamped in order to separate the functions of extension and 2D displacement.
  • the 2D piezoelectric actuator can be used to move a fibre relative to a lens 50.
  • a support structure 52 with an abutment surface 104 is provided to clamp the end of the piezoelectric actuator when powered down.
  • the lens 50 is attached to the block 105 which incorporates the abutment 104.
  • Figure 4b shows a similar configuration to the configuration of figure 4a with a fibre fixed to a support block 51 and a lens 50 attached to the piezoelectric actuator for movement one relative to the other. Once again the piezoelectric actuator locks in position when unpowered since it extends more rapidly than it returns from its lateral deflections.
  • Figure 5a and figure 5b show respectively a length wise cross-sectional view and a lateral cross-sectional view of a manually actuated optical switch.
  • Figure 5a shows an optical switch using a rotatable prism with light coupled in and out of fibres via collimators.
  • Moving prism 201 is of a periscope type in this embodiment giving a high tolerance to positional misalignment.
  • a fixed right prism 202 is used to route the light out of the moving prism to the output collimator 206.
  • the collimators include five input collimators 207 and a single output collimator 206 which are aligned in a circle with their beams aligned parallel to each other and the axis of the switch.
  • the radius of the collimator circle is kept to a minimum to reduce alignment tolerances needed for the rotating prism and supports to ideally around 2mm.
  • the rotating prism is attached to one end of a shaft 203 supported by a pair of bearings 204.
  • the opposite end of the shaft is attached by a pin 301 to an actuating knob 205.
  • a ball bearing 210 is located on a flexure plate or the like 212 is provided at a radius of around 5mm so as to engage with recesses provided on a detent plate 11 in order to secure the switch at predetermined locations for switching.
  • the knob can be isolated by a compliant linkage to prevent any influence on the optical coupling by external forces of the actuator.
  • Figure 6a shows a linear slide switch in a first switch position whilst figure 6b shows a linear slide switch in a second position which faces the fifth output collimator.
  • this one by five optical switch is similar to the previous embodiment but configured as a slide switch.
  • the coupling is direct between collimators, one of which is mounted on a linear slide 225 and is referenced 224.
  • a five position detent rack 231 is engaged by the ball bearing 230 sprung on the coupling flexure 229 to a selection of five possible positions.
  • Flexure 229 is also joined to slide knob 232 and located in slide groove 233.
  • the fibre 227 is attached to moving fibre support 226 and then laid out in fibre support track 228 to allow movement whilst both providing support and preventing excessive modulation or damage from vibration.
  • the fibre is attached to the support tray at point 234 and then is joined to input connector 221. Direct short path coupling between collimators achieves maximum flexibility in terms of multimode /single mode operation, wavelength flexibility and potential for lowest losses.
  • the input ports are generally referenced 222 with the fifth collimator being referenced 223.
  • the common port collimator could be fixed and arranged to point along the axis of the slide with a mirror mounted at 45 degrees on the slide to direct the light between the common collimator and the other ports. This would avoid the need for moving the fibre but at the expense of a longer and variable path length and an additional optical element with double the sensitivity to tilt.
  • Various terminations such as bare fibre for splicing; flying connectorised cables; female sockets to accept cables or a combination of the above;
  • the switches may be free space between collimators

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Optical Communication System (AREA)

Abstract

An optical beam steering arrangement comprising a collimator, a powered actuator for displacing an optical element; said displaceable optical element being said collimator or an optical element which is in communication with said collimator and clamping means which is released when said actuator is powered up for displacing said optical element and which immobilises the displaced element in a displaced position on power down.

Description

Beam Steering Arrangements and Optical Switches
Field of the Invention
The invention relates to optical beam steering arrangements and optical switches.
Background to the Invention and Prior Art Known to the Applicant(s)
The following prior art documents are acknowledged: US6819820; US2003/53055; US2003/49879; US2002/171420; and US2002/76139.
The following prior art documents which relate in part to manually actuated optical switches are acknowledged: US4470662; US2004/57659; GB1217092; US4441785; GB2295687; US5046806; US4919512; US4991925; US4442425; CB2285517; GB2238625; and US5133030.
The closest prior art documents are the applicant's own prior published patent documents and in particular: GB2378573 and GB2390910 Summary of the Invention
In a first broad independent aspect, the invention provides an optical beam steering arrangement comprising a collimator, a powered actuator for displacing an optical element; said displaceable optical element being said collimator or an optical element which is in communication with said collimator; and clamping means which is released when said actuator is powered up for displacing said optical element and which immobilises the displaced element in a displaced position on power down.
This configuration is particularly advantageous because it allows the displaceable optical element to be held accurately in position even when the actuator is powered down. This configuration also improves reliability and the likely longevity of the beam steering arrangement.
In a subsidiary aspect in accordance with the invention's first broad independent aspect, said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means against which the bender abuts on power down; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release the actuator from the abutment to facilitate displacement in lateral directions; and following lateral displacement on power down said bender abuts said abutment and immobilises the displaced bender in a displaced position.
This configuration is particularly advantageous because it allows a piezoelectric bender which is already incorporated into the beam steering arrangement as the primary driver of the actuation to also achieve clamping. This configuration minimises the number of components required to achieve clamping.
In a further subsidiary aspect, said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means; said abutment and said bender forming a jaw for immobilising a displaceable component of the arrangement; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release said component from said jaw to facilitate displacement in lateral directions; and following lateral displacement on power down said jaw closes onto said component to immobilise it in a displaced position.
This configuration also provides an advantageous form of clamping whilst using the piezoelectric bender itself whilst cooperating with an abutment.
In a further subsidiary aspect, the actuator incorporates a bender, an optical element carrier and a flexure joining said bender to said optical element carrier; and the flexure is said displaceable component located between said abutment and said bender in order to allow the bender and abutment to form a jaw for clamping the flexure.
This configuration is particularly advantageous because it provides a particularly secure clamping mechanism without running the risk of causing any damage to collimators or other more sensitive components.
In a further subsidiary aspect, said actuator incorporates at least one bender and the abutment is part of a second bender. This is particularly advantageous because it allows the thermal expansion of two benders to be particularly well matched. It may also allow a clamp gap to be isolated from any effects of bending the substrate.
In a further subsidiary aspect, the first and second benders incorporate slots and are 1-D benders with lines of action at right angles from one another. This achieves a particularly symmetrical configuration with improved mechanical properties.
In a further subsidiary aspect, said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a second piezoelectric component is provided to clamp said flexure. This configuration achieves the advantages of clamping whilst separating the displacement of the optical element from the action of securing the displaced element in position.
In a further subsidiary aspect, said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a magnetic element is provided to clamp said flexure. This configuration is an alternative to the previous configuration which also achieves the advantages of separating the displacement actuation from the clamping actuation.
In a further subsidiary aspect, the arrangement further comprises an optical element carrier; a flexure located at a further most region of said arrangement where the displacement is higher than at other regions of said arrangement; and clamping means for immobilising said flexure. This configuration reduces the sensitivity to position offsets which can be present due to the clamping operation.
In a second broad independent aspect, the invention provides an optical switch comprising at least an input port and a plurality of output ports; and a manually accessible component which when actuated displaces a displaceable arrangement which switches light originating from a selected input on a path to a selected output; characterised in that the switch has one or more of the following features:
(A) A slidable manually accessible component and a slidable carrier carrying a beam inputting element; wherein said carrier slides when said component is displaced in order to establish optical communication between said element located on said carrier and a corresponding element for transmission to an output port;
(B) input and output elements located in a common arc with the elements facing in the same direction; and a first reflective arrangement intercepting light from an input element and directing a beam towards a second reflective arrangement which directs a beam to an output element; wherein one of said reflective arrangements is fixed and another is rotatable in order to rotate when said manually accessible component is itself rotated.
Configuration (A) is particularly advantageous because it allows an operator to manually accurately control the switching from one input port to an output port. It also provides a relatively compact switch with improved positional accuracy when compared to the prior art documents.
With regard to feature (B), this configuration further improves the compactness of the switch since both the input and output ports can be located on the same side of the switch whilst only one component is moved which allows improved repeatability, switch lifetime and speed of operation. Both of these configurations achieve these improvements without the need for external power and electronic systems and therefore preserve the simplicity of set up which is well known from connectors.
In a subsidiary aspect in accordance with the invention's second broad independent aspect, said slidable carrier runs on a track and a detent is provided to releasably secure said carrier in predetermined positions on said rack.
In a further subsidiary aspect, said detent incorporates a resilient protrusion which meets with a plurality of recesses located at said predetermined positions. This configuration is particularly advantageous in terms of repeatability and overall accuracy.
In a further subsidiary aspect, said beam inputting element is a collimator. This is particularly advantageous when the optical switch is a free space optical switch.
In a further subsidiary aspect, said beam inputting element is a reflector located on said carrier and the reflector is in communication with a fixed collimator. This configuration also achieves advantageous repeatability.
In a further subsidiary aspect, said beam inputting element is a refractor located on said carrier and the refractor is in communication with a fixed collimator. This also minimises the moveable components required in order to achieve accurate switching which is actuated manually.
In a further subsidiary aspect, said rotatable arrangement runs on a track and a detent is provided to releasably secure said rotatable arrangement in predetermined positions on said track. This allows the operation of manually switching to be accurately achieved.
In a further subsidiary aspect, said detent incorporates a resilient protrusion which meets with a plurality of recesses located at said predetermined positions. This configuration is particularly advantageous due to its repeatability whilst permitting manually driven actuation. Brief description of the figures
Figure 1 shows a beam steering arrangement in side elevation with parts in cross-section.
Figure 2a shows a piezoelectric bender and its drive arrangement in schematic form for achieving up/down movement and lengthening and shortening.
Figure 2b shows a piezoelectric bender and its drive arrangement in schematic form for achieving lateral movement and lengthening and shortening.
Figure 2c shows a cross-sectional view of the piezoelectric bender.
Figure 3a shows a perspective view of two slotted benders.
Figure 3b shows a side elevation view of two slotted benders.
Figure 4a shows a side elevation view of an arrangement where the bender displaces the fibre behind a fixed lens.
Figure 4b shows a side elevation view of an arrangement where the bender displaces a lens in front of a fixed fibre.
Figure 5a shows a manually operated periscope switch in cross-sectional view.
Figure 5b shows an optical operational end view of the switch of figure 5a.
Figure 6a shows a manually operated slider switch in plan view in a first position.
Figure 6b shows a manually operated slider switch in plan view in a second position. Detailed Description of the Figures
In this application the terms input and output may be used interchangeably since the input of an optical switch may become an output dependent upon the direction of communication selected.
Figure 1 shows a modification of a piezoelectric actuated collimator to collimator switch of the type described in GB2390910. In this switch, the angles of the collimators are set by moving a rear flexure 4 of a parallel flexure pair referenced 4 and 5 in figure 1 attached to each of the collimators at either end of the switch. The flexures are relatively thin plates of flexible material. Flexure 4 extends between a mounting block 10 which is secured to the free extremity 101 of the piezoelectric bender 2 and flexure 4.
The piezoelectric bender is secured to a support 9 via a mount 1 of known kind. The piezoelectric bender 2 may be a two dimensional bimorph capable of moving laterally upwards, downwards, right and left relative to the longitudinal axis of the bender. The displacement of the end of the bender may be in the X, Y and Z directions as shown in figure 2b. When energised the bender is also capable of extension if the bias voltage supplied is varied due to the symmetric source 20 and 21 of figure 2b. A solid plate 8 is provided between flexure pair 4 and 5 so that when the piezoelectric bender is extended it clamps flexure 4 between the solid plate and the block. In this configuration, the solid plate forms an abutment against which the piezoelectric bender abuts to secure the flexure in position.
The voltage is applied to the bender so that in its unpowered state, the natural length of the piezoelectric bender is longer than the distance between its mount 1 and the plate 8 so that the flexure is locked in place. When the bias is applied, the bender's length reduces permitting the bender to control the pointing angle of the collimator in the manner exemplified in GB2390910. By rapidly removing the bias voltage, the bender locks in place in a new position. This process is helped by the lengthwise actuation speed being much faster than the left /right; up /down adjustment response time of the actuator. The lengthwise resonance of the piezo is set by the velocity of sound along the length of the piezo, and is around 2OkHz compared to the left/right up/down actuator resonances which is around 200Hz. Small offset errors, if any, introduced in the clamping process can, if necessary, be pre- compensated by deliberately offsetting the initial pointing angle of the collimator. The result of the clamping process may be checked by energising feedback position sensors or by measuring the optical transmission, and the clamping process repeated on an individual actuator basis if needed. An advantage of the position sensor feedback over optical power feedback is that it tells the controller which way and by how much the initial point needs to be adjusted to get the collimator in the right place after clamping.
As in GB23909110 the optical element displaced by this particular arrangement is a collimator 7 which is carried by a carrier 6. The collimator 7 is joined to a fibre 3 which passes through openings provided in both flexures 4 and 5. The fibre 3 may be secured to the bender through an adhesive point 102 as appropriate.
Figure 2A shows the manner in which a 1 D piezoelectric actuator may be driven to achieve extension and contraction as well as up and down motion.
Figure 2B shows the connections necessary for a 2-D piezoelectric actuator of the kind discussed with reference to figure 1.
Figure 2C shows the cross-section of the bender with a succession of electrode plates amongst piezoelectric material.
Further examples of piezoelectric actuators can be utilised such as those shown in GB2378573.
As an alternative embodiment, a separate piezoelectric clamp actuator may be used for immobilising the flexure plate. This piezoelectric actuator may be an extension and contraction actuator which traps the plate against an abutment of the kind shown in figure 1.
In a further embodiment, the invention envisages the use of a separate magnetic clamp which may close onto an otherwise mobile flexure. In a further embodiment, a clamp flexure may be attached to carrier 6 or to a distal extremity 103 of the collimator in order to reduce the sensitivity to position offsets created in the clamping operation.
The clamp is preferably undamped when energised and arranged to permit full clamping when powered down.
The figures 3a and 3b show a piezoelectric actuator assembly attached to a support structure at end piece 33. The left right movement is provided by a slotted bimorph 3Z joined to a similar slotted bimorph 31. In the clamped state, bimorph 31 is unbiased and abuts into end piece 33. Bimorph 32 can either be always unbiased or for greater relative clamping displacement at the expense of having to maintain a voltage in the clamped state, it can be unbiased during movement and biased in the clamped state. A collimator 7 employs two flexures 44 and 45 to secure respectively to end piece 33 and bimorph 31 enabling angle adjustment of the collimator in both axes when free and locked in angle when clamped. This structure has the advantage that the thermal expansion of the two piezoelectric elements is well matched and the clamp gap is isolated from any effects of bending the substrate.
As a further embodiment, the piezoelectric actuator 31 can be replaced by a 2D bimorph and piezoelectric actuator 31 by a passive piezoelectric strut.
Alternatively, piezoelectric actuator 32 can be a 2 D bimorph and piezoelectric actuator 31 can be an extension plate, biased when free, and unbiased when clamped in order to separate the functions of extension and 2D displacement.
As a further embodiment, as shown in figure 4a the 2D piezoelectric actuator can be used to move a fibre relative to a lens 50. In this embodiment, a support structure 52 with an abutment surface 104 is provided to clamp the end of the piezoelectric actuator when powered down. The lens 50 is attached to the block 105 which incorporates the abutment 104.
Figure 4b shows a similar configuration to the configuration of figure 4a with a fibre fixed to a support block 51 and a lens 50 attached to the piezoelectric actuator for movement one relative to the other. Once again the piezoelectric actuator locks in position when unpowered since it extends more rapidly than it returns from its lateral deflections.
Figure 5a and figure 5b show respectively a length wise cross-sectional view and a lateral cross-sectional view of a manually actuated optical switch.
Figure 5a shows an optical switch using a rotatable prism with light coupled in and out of fibres via collimators. Moving prism 201 is of a periscope type in this embodiment giving a high tolerance to positional misalignment. A fixed right prism 202 is used to route the light out of the moving prism to the output collimator 206. The collimators include five input collimators 207 and a single output collimator 206 which are aligned in a circle with their beams aligned parallel to each other and the axis of the switch.
The radius of the collimator circle is kept to a minimum to reduce alignment tolerances needed for the rotating prism and supports to ideally around 2mm. The rotating prism is attached to one end of a shaft 203 supported by a pair of bearings 204. The opposite end of the shaft is attached by a pin 301 to an actuating knob 205. A ball bearing 210 is located on a flexure plate or the like 212 is provided at a radius of around 5mm so as to engage with recesses provided on a detent plate 11 in order to secure the switch at predetermined locations for switching. Optionally, the knob can be isolated by a compliant linkage to prevent any influence on the optical coupling by external forces of the actuator.
Figure 6a shows a linear slide switch in a first switch position whilst figure 6b shows a linear slide switch in a second position which faces the fifth output collimator.
Functionally this one by five optical switch is similar to the previous embodiment but configured as a slide switch. However, the coupling is direct between collimators, one of which is mounted on a linear slide 225 and is referenced 224. A five position detent rack 231 is engaged by the ball bearing 230 sprung on the coupling flexure 229 to a selection of five possible positions. Flexure 229 is also joined to slide knob 232 and located in slide groove 233. The fibre 227 is attached to moving fibre support 226 and then laid out in fibre support track 228 to allow movement whilst both providing support and preventing excessive modulation or damage from vibration. The fibre is attached to the support tray at point 234 and then is joined to input connector 221. Direct short path coupling between collimators achieves maximum flexibility in terms of multimode /single mode operation, wavelength flexibility and potential for lowest losses. The input ports are generally referenced 222 with the fifth collimator being referenced 223.
As an alternative embodiment, the common port collimator could be fixed and arranged to point along the axis of the slide with a mirror mounted at 45 degrees on the slide to direct the light between the common collimator and the other ports. This would avoid the need for moving the fibre but at the expense of a longer and variable path length and an additional optical element with double the sensitivity to tilt.
The invention also envisages a manually actuated optical switch with any of the following characteristics:
■ Two or more movable periscope prisms; " A collimator attached to a rotating arm;
■ An actuating knob loosely coupled to the moving optical element;
■ The switch being actuated from outside a hermetic seal;
■ The fibre bending through substantially 180 degrees between being attached to the moving and fixed parts of the structure; ■ Various types of manual actuators such as a knob, a rocker, a toggle and a slider;
■ Varying levels of environmental sealing from non to full hermetic which would include actuation via magnetic coupling or direct mechanical coupling via a flexure;
■ Transition between states - click over action or centre off;
■ Various terminations such as bare fibre for splicing; flying connectorised cables; female sockets to accept cables or a combination of the above;
■ The switches may be free space between collimators;
■ Free space between cleaved fibre ends;
■ Combined with moving collimator, moving prism (reflective or refractive)

Claims

1. An optical beam steering arrangement comprising a collimator, a powered actuator for displacing an optical element; said displaceable optical element being said collimator or an optical element which is in communication with said collimator and clamping means which is released when said actuator is powered up for displacing said optical element and which immobilises the displaced element in a displaced position on power down.
2. An arrangement according to claim 1, wherein said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means against which the bender abuts on power down; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release the actuator from the abutment to facilitate displacement in lateral directions; and following lateral displacement on power down said bender abuts said abutment and immobilises the displaced bender in a displaced position.
3. An arrangement according to claim 1, wherein said actuator is part of said clamping means and incorporates a piezoelectric bender secured onto a support structure; the arrangement further comprising an abutment as part of said clamping means; said abutment and said bender forming a jaw for immobilising a displaceable component of the arrangement; and on power up an applied voltage causes lateral movement of said bender and the shortening of the bender in order to release said component from said jaw to facilitate displacement in lateral directions; and following lateral displacement on power down said jaw closes onto said component to immobilise it in a displaced position.
4. An arrangement according to claim 3, wherein the actuator incorporates a bender, an optical element carrier and a flexure joining said bender to said optical element carrier; and the flexure is said displaceable component located between said abutment and said bender in order to allow the bender and abutment to form a jaw for clamping the flexure.
5. An arrangement according to claim 2, wherein said actuator incorporates at least one bender and the abutment is part of a second bender.
6. An arrangement according to claim 5, wherein the first and second benders incorporate slots and are 1-D benders with lines of action at right angles from one another.
7. An arrangement according to claim 1, wherein said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a second piezoelectric component is provided to clamp said flexure.
8. An arrangement according to claim 1, wherein said actuator incorporates a piezoelectric component, an optical element carrier and a flexure joining said piezoelectric component to said optical element carrier; and a magnetic element is provided to clamp said flexure.
9. An arrangement according to claims 1, further comprising an optical element carrier; a flexure located at a furthermost region of said arrangement where the displacement is higher than at other regions of said arrangement ; and clamping means for immobilising said flexure.
10. An optical beam steering arrangement substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or figures.
11. An optical switch comprising at least an input port and a plurality of output ports; and a manually accessible component which when actuated displaces a displaceable arrangement which switches light originating from a selected input on a path to a selected output; characterised in that the switch has one or more of the following features:
a) a slidable manually accessible component and a slidable carrier carrying a beam inputting element; wherein said carrier slides when said component is displaced in order to establish optical communication between said element located on said carrier and a corresponding element for transmission to an output port; b) input and output elements located in a common arc with the elements facing in the same direction; and a first reflective arrangement intercepting light from an input element and directing a beam towards a second reflective arrangement which directs a beam to an output element; wherein one of said reflective arrangements is fixed and another is rotatable in order to rotate when said manually accessible component is itself rotated.
12. An optical switch according to claim 11, wherein said slidable carrier runs on a track and a detent is provided to releasably secure said carrier in predetermined positions on said track.
13. An optical switch according to claim 12, wherein said detent incorporates a resilient protrusion which mates with a plurality of recesses located at said predetermined positions.
14. An optical switch according to any of claims 11 to 13, wherein said beam inputting element is a collimator.
15. An optical switch according to any of claims 11 to 13, wherein said beam inputting element is a reflector located on said carrier and the reflector is in communication with a fixed collimator.
16. An optical switch according to any of claims 11 to 13, wherein said beam inputting element is a refractor located on said carrier and the refractor is in communication with a fixed collimator.
17. An optical switch according to claim 11, wherein said rotatable arrangement runs on a track and a detent is provided to releasably secure said rotatable arrangement in predetermined positions on said track.
18. An optical switch according to claim 17, wherein said detent incorporates a resilient protrusion which mates with a plurality of recesses located at said predetermined positions.
19. An optical switch substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or figures.
PCT/GB2006/004123 2005-11-04 2006-11-06 Beam steering arrangements and optical switches WO2007052053A2 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB0522535A GB0522535D0 (en) 2005-11-04 2005-11-04 Latching optical switch
GB0522535.4 2005-11-04
GB0522929A GB0522929D0 (en) 2005-11-10 2005-11-10 Mechanically actuated optical switches
GB0522929.9 2005-11-10

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WO2007052053A2 true WO2007052053A2 (en) 2007-05-10
WO2007052053A3 WO2007052053A3 (en) 2007-07-12

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WO2019032790A1 (en) * 2017-08-11 2019-02-14 Caprice Gray Haley Wire handling apparatus

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EP0424609A1 (en) * 1989-09-28 1991-05-02 Rockwell International Corporation Piezoelectric actuator

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MILTON G ET AL: "Vision based ultra-precision centering of optical fibers for microlens fabrication" INTELLIGENT ROBOTS AND SYSTEMS, 2004. (IROS 2004). PROCEEDINGS. 2004 IEEE/RSJ INTERNATIONAL CONFERENCE ON SENDAI, JAPAN 28 SEPT.-2 OCT., 2004, PISCATAWAY, NJ, USA,IEEE, vol. 3, 28 September 2004 (2004-09-28), pages 3045-3049, XP010766184 ISBN: 0-7803-8463-6 *

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019032790A1 (en) * 2017-08-11 2019-02-14 Caprice Gray Haley Wire handling apparatus

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