Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light

Definitions

• the present invention is directed to a technique for routing optical beams using micro-structures.
• Optical switching has many applications in data communication, data processing, and data recording.
• the main obstacles to wider use of optical switching are cost, complexity, and reliability.
• Different techniques for optical switching have been used, including liquid crystal and piezo-electric technologies.
• LCD Current Liquid Crystal Display
• SPZT Stacked piezoelectric structures
• PZT piezoelectric
• PM lead manganese niobate
• current SPZT devices suffer from high current operation, significant actuator nonuniformity, heavy weight, relatively high power dissipation, and moderate hysteresis effect.
• these devices are relatively expensive when compared to LCD devices.
• the liquid crystal and piezoelectric, optical activities are deleteriously affected by power interruptions.
• an optical router including an optical micro-element having plural operable states, said optical microelement actuatable to change operable states, wherein a change in the operable state of said optical micro-element changes the direction of an optical beam; characterized in that a micro-latch is provided having plural conditions, said micro-latch actuatable to change conditions, one of said conditions maintaining the operable state of said optical micro-element.
• an optical router comprising at least one moveable optical micro-element having plural operable states and a micro-actuator operatively connected to said optical micro-element, said micro-actuator arranged to effectuate the changing of the operable state of said optical micro-element, characterized in that a change in the operable state of said optical micro-element is accompanied by said optical micro-element moving in a direction defining a movement direction; said optical micro-element being arranged in one of said states to intercept an optical beam supplied from a direction generally perpendicular to said reference direction and being arranged in another said state to deflect said intercepted optical beam into another direction generally perpendicular to said reference direction.
• Figure 1 is a schematic of controllably routing optical beams using at least one bistable optical micro-switch.
• Figure 2(A) is a top view of a micro-actuator according to an implementation of a preferred embodiment of the present invention
• Figure 2(B) is a cross sectional view of a micro-actuator according to an implementation of a preferred embodiment of the present invention
• Figure 3(A) is a schematic showing the micro-latch not engaged according to an implementation of a preferred embodiment of the present invention
• Figure 3(B) is a schematic showing the micro-latch engaged according to an implementation of a preferred embodiment of the present invention
• Figure 4(A) is a timeline of the normal operation of the optical router according to an implementation of a preferred embodiment of the present invention
• Figure 4(B) is a timeline of the operation of the optical router according to an implementation of a preferred embodiment of the present invention when there is an electrical power interruption;
• Figure 5 is a schematic of an implementation of a preferred embodiment of the present invention using a single micro-switch including a planar reflecting mirror as the optical micro-element;
• Figure 6 is a schematic of an implementation of a preferred embodiment of the present invention using a two by two array of optical micro-switches, each including a planar reflecting mirror as the optical micro-element.
• optical beams are controllably routed using at least one bistable optical micro-switch, the optical micro- switch including at least one optical micro-element and a vertical micro-actuator.
• the inventive approach places at least one optical micro-element (e.g., a planar or curved mirror, or a lens) on a platform displaced by a bistable vertical micro-actuator to control the directing of optical beams. More particularly, the direction of optical beams is controlled by at least one optical micro-element that is placed on a vertical micro-actuator; the actuator being biased by at least one micro- spring; and the combination of the micro-element and the micro-actuator being selectively held in place by a micro-latch.
• the optical micro-element e.g., a planar or curved mirror, or a lens
• the inventive approach has the advantage of using relatively lightweight micro-structures, manufacturable by integrated circuit processing technology, to control the directing of optical beams. Moreover, these micro-structures are simple, have high dynamic range, are highly predictable and repeatable in their performance, and do not suffer from hysteresis.
• the inventive approach in a simple and inexpensive manner, can be used to control the directing of at least one optical beam into plural inputs in a bistable manner and, therefore, in a manner immune to power interruptions.
• the inventive approach routes optical beams consuming low power and using low voltage signals.
• a micro-component refers to a component having dimensions suitable for manufacturing using semiconductor device fabrication techniques (including but not limited to MEMs fabrication or micro-machining).
• the inventive approach controllably routes optical beams using at least one bistable optical micro-switch.
• this embodiment includes an optical micro- switch 110 (having two positions that are operatively stable; one position is mechanically quiescent and the other position is electrically activated), a micro-latch 150, and a drive circuit 120 providing electrical power and signals.
• an optical beam 100 is directed by the optical micro-switch 1 10 being in one of its two stable positions (e.g., up position). The optical beam 100 continues in its original direction when the micro-switch 1 10 is in the other stable position (e.g., down position).
• the optical micro-switch 1 10 stays in either of its two operating positions in a stable manner.
• an optical micro-element is operatively connected to (e.g., directly, or indirectly, supported by) a vertical micro-actuator to form the optical micro-switch 1 10.
• Figures 2(A) and 2(B) show a top view and a cross sectional view, respectively, of an exemplary implementation of a vertical micro-actuator according to a preferred embodiment of the present invention.
• a micro-actuator includes at least one upper interdigitated micro-finger(s) 221 connected to a platform 222 on which is placed the optical micro-element (not shown in Figure 2); at least one lower interdigitated micro-finger(s) 223 connected to support 224; and plural micro-springs 225, wherein a micro-spring has at least one end 225- 1 connected to the platform 222 through a spacer 226 and has at least another end 225-2 connected to the support 224 through another spacer 226.
• the optical micro-element is grown on, or attached to, the platform 222.
• the optical micro-element (not shown in Figure 2) on the platform 222 is free from attachments to any component other than the platform 222 of the micro-actuator.
• the micro-actuator according to the present invention can be implemented by having more than, or less than, two sides of the platform 222 and the support 224 connected to micro-springs.
• the micro-actuator according to the present invention can be implemented by having more than one micro-spring connected to a side of a platform.
• two micro-springs can be used to connect a side of the platform 222 with a side of the support 224; a single spring with two connections at each end can be used to connect a side of the platform 222 with a side of the support 224; two springs joined at each end can be used to connect a side of the platform 222 with a side of the support 224; or a combination thereof.
• micro-actuator according to the present invention can be implemented using shapes other not four-sided, including triangular, pentagonal, hexagonal, circular, and non-uniform shapes. Instead of using two sets of interdigitated micro-fingers, the micro-actuator according to the present invention can also be implemented using a single rod in a housing.
• the micro-spring spacers 226 can be chosen to avoid having the upper and lower sections of the micro-actuator be at the same electrical potential.
• the micro-actuators can be manufactured according to integrated circuit fabrication techniques (including, but not limited to, MEMs fabrication and micro-machining) .
• the micro-actuators can be fabricated using polycrystalline silicon, single crystal silicon, or metallic material.
• the micro- actuator is in the up position (the mechanically quiescent position) when it is electrically not biased because the micro-springs 225 prefer a mechanically quiescent state that minimizes the stored mechanical energy in the micro-springs 225.
• the micro-actuator is in the down state when there is an electrical potential difference between the upper and lower interdigitated micro-fingers (221 and 223, respectively) of the micro- actuator. In this case, the upper and lower interdigitated micro-fingers (221 and 223, respectively) tend to maximize their overlapped areas to minimize the stored electrical energy— this tendency is opposed by the mechanical energy stored in the stretched micro- springs.
• the micro-actuator is in the down position when it is electrically not biased and therefore the upper and lower interdigitated micro-fingers overlap; the down state being the mechanically quiescent state.
• the upper and lower interdigitated micro fingers of the micro-actuator are charged to the same nonzero electrical potential.
• the upper and lower interdigitated micro-fingers repel each other to minimize their overlapped areas and, thus, to minimize the stored electrical energy— this tendency is opposed by the mechanical energy stored in the stretched micro-springs.
• the micro-actuators can implement the micro-actuators using arrangements that are non-electric field based.
• the micro-actuator can be implemented using arrangements reacting to changing magnetic fields.
• one skilled in the art can use other means for providing mechanically quiescent positions.
• magnetic or gravitational forces instead of the micro-springs, can be used to achieve the mechanically quiescent position.
• the micro-actuator is implemented as a micro-comb drive.
• the micro-actuator is implemented as a vertical micro-comb drive.
• FIGS 3(A) and 3(B) show top view schematics of an exemplary lateral micro-latch 350 according to a preferred embodiment of the present invention in a released position and an engaged position, respectively.
• the lateral micro-latch 350 includes a micro-pad 351 (which acts as a pawl or a tang) connected to micro-arm 352, which is connected to a first micro- base 353- 1.
• the micro-arm 352 is connected to a first set of interdigitated micro-fingers 354-1.
• the micro- latch 350 according to the present invention can be manufactured according to integrated circuit fabrication techniques and can be made of single crystal, or polycrystalline, silicon or metal.
• Figure 3(A) shows the situation where the interdigitated micro- fingers 354- 1 and 354-2 are not charged and, therefore, the spring action of the micro-arm 352 and the micro-base 353- 1 keeps the micro-pad 351 from being in the path of the micro-switch 310.
• Figure 3(B) shows the situation where the interdigitated micro-fingers 354- 1 and 354-2 have a potential difference and, therefore, the micro fingers 354- 1 and 354-2 overlap to minimize the stored electrical energy stored as balanced by the spring action of the micro-arm 352 and micro-base 353. The overlapping action of the interdigitated micro-fingers 354- 1 and 354-2 pulls the micro- pad 351 into the path of the optical micro-switch 310.
• the interdigitated micro-fingers 354- 1 and 354-2 may have a curving profile to allow their unimpeded angular motion.
• the situation of Figure 3(A) is used along with the micro-switch being in the up position when the interdigitated micro- fingers of the micro-actuator are not charged.
• the situation of Figure 3(B) is used when the micro-switch is in the down position as a result of the interdigitated micro-fingers of the micro-actuator fingers being charged to a potential difference.
• the micro-latch 350 is in a position that can engage the micro-switch 310 and therefore can keep it from going into the up position when the electrical power is interrupted.
• the frictional force between the micro-pad 351 and micro-switch 310 stops the micro-latch 350 from disengaging.
• the micro-switch 310 (either the micro- actuator or the micro-element, or both) moves to the down position first and then is followed by the micro-latch 350 moving into the engaging position. If the micro-switch 310 is to selectively move into the up position from a down position, then the micro-latch 350 is moved into the disengaging position first and then is followed by the micro-switch 310 moving into the up position.
• the circuit that drives the micro-switch 310 to move up has a trigger time that is longer than the trigger time of the circuit that disengages the micro-latch 350; thus allowing the micro-latch 350 to disengage before the micro-switch 310 is allowed to move up.
• the circuit that drives the micro-switch has a trigger time that is longer than the trigger time of the circuit that disengages the micro-latch 350; thus allowing the micro-latch 350 to disengage before the micro-switch 310 is allowed to move up.
• the 350 to move down has a trigger time that is shorter than the trigger time of the circuit that engages the micro-latch 350; thus allowing the micro- latch 350 to engage after the micro- switch 310 is allowed to move down.
• micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad 351 are selectively driven to be in the path of the micro-switch, the micro-pad
• micro-latch 350 does not physically contact the micro-switch 310 (i.e. , the micro-pad neither contacts the micro-actuator nor the micro-element) unless the micro-switch 310 is in the down position and the electrical power is interrupted. Consequently, the micro-latch 350 can continuously operate without wear unless there is an excessive number of power interrupts.
• the micro-latch is implemented using a micro-comb-drive.
• Figures 4(A) and 4(B) show a non-limiting implementation of the timelines in a preferred embodiment for the normal operation of the optical router wherein the micro-latch contacts the optical micro-switch (the micro-element or the micro-actuator, or both) only when electrical power is interrupted.
• Figure 4(A) shows the timeline of the activation of the micro-switch as driven by the signal on line 401 and the micro-latch as driven by the signal on line 402 during normal operation wherein the micro-switch goes from the up state (mechanically quiescent) to down state (electrically activated) and then back into the up state. At time to a signal is applied to the micro- switch to begin driving it into the down state.
• the micro-switch is in the down state.
• a signal is applied to the micro-latch to begin driving it into the path of the micro- switch.
• the micro-latch is in the path of the micro-switch but does not contact it because the micro-switch is already in the down state.
• the power remains until it is desired to change the state of the optical micro-switch from the down state to the up state whereupon at time a signal is applied to the micro-latch to begin driving it out of the path of the micro-switch.
• a signal is applied to the micro- switch to begin driving it into the up state without the micro-latch being in the path of the micro- switch.
• the timeline in the event of an electrical interruption is schematically shown in Figure 4(B), wherein the micro-switch is in the down position (mechanically tensed) and the micro-latch is in the path of the micro-switch.
• electrical power is interrupted.
• time t ⁇ as supplied on line 401 , the electrical signal maintaining the state of the optical micro-switch begins to decay and the micro-switch begins to go up responding to the unbalanced mechanical force.
• the drive circuit 120 is configured to ensure that the electrical signal, as supplied on line 402, maintains the position of the micro-latch (e.g., the micro-pad) in the path of the micro-switch.
• the voltage on line 402 begins to decay at a later time t 13 , which is after the time t ⁇ 2 when the micro- switch contacts the micro-latch.
• the micro-latch is, therefore, maintained in the path of the now moving micro-switch.
• the micro-latch holds the micro-switch in its mechanically tensed state.
• the micro-latch may be retained in the latching position by friction force or an implementation of an interlocking mechanism such as fingers or hooks provided on the micro-pad 351.
• the micro-switch and the micro-latch are electrically activated as in Figure 4(A).
• the micro- latch 350 (e.g., the micro-pad 351) can be implemented to contact the optical micro-element or the micro-actuator, or both.
• the micro-latch 350 according to the present invention can also be implemented to have the interdigitated micro-fingers 354- 1 and 354-2 repulse each other.
• the interdigitated micro-fingers 354- 1 and 354-2 can be arranged to normally overlap when they are not charged.
• the micro-latch 350 can also be implemented in other arrangements.
• the micro-pad 351 is placed on the same side of the micro-arm 352 as the first micro-base 353- 1
• the second micro-base 353-2 and the interdigitated micro-fingers 354- 1 and 354-2 are placed on the other side of the micro-arm 352 from the first micro- base 353- 1.
• the micro-pad 351 is placed on the other side of the micro-arm 352 from the first micro-base 353- 1 , and the second micro-base 353-2 and the interdigitated micro-fingers 354- 1 and 354-2 are placed on the same side of the micro-arm 352 as the first micro-base 353- 1.
• the micro-pad 351 , the second micro-base 353-2, and the interdigitated micro-fingers 354- 1 and 354-2 are placed on the other side of the micro-arm 352 from the first micro-base 353- 1.
• the choice of whether a potential difference is applied between the interdigitated micro-fingers 353- 1 and 353-2 (or whether they are charged up by the same electric potential) depends on whether the micro-pad 351 is to move into, or out of, the path of the micro-switch 310.
• a micro-switch includes at least one optical microelement and at least one micro-actuator as described above.
• a micro-actuator in the exemplary embodiments described below is arranged as in Figure 2(A) with the micro- springs being non-tensed when the micro-switch is in the up position.
• Other arrangements for the micro-actuator can be used in the exemplary embodiments described below without departing from the invention herein disclosed.
• a micro-actuator arrangement is chosen to minimize the overall time the micro-spring is placed in tension. This is achieved, for example, by determining the most frequent routing direction of an optical beam and choosing an arrangement for the micro-switch (the micro-element) that achieves this routing without the need for tensing the micro-spring— which arrangement therefore is stable if electrical power is interrupted.
• the router can also choose to fabricate the router using the arrangement that is most easily, or economically, manufacturable.
• FIG. 5 shows a schematic of an exemplary preferred embodiment according to the present invention wherein a single bistable micro-switch controls the routing of an optical beam to two receivers.
• an optical micro- switch 510 in the up position routs an optical beam 500 delivered from an optical fiber 561.
• the fiber 561 is held in place by a fiber holder 571 that has a micro-lens 581 placed between the fiber 561 and the micro-switch 510.
• the micro-switch 510 in the up position routs the optical beam 500 to optical fiber 562, which is held in place by holder 572, through micro-lens 582.
• micro-switch 510 If the micro-switch 510 is in the down position, then it routs the optical beam 500 to optical fiber 563, which is held in place by holder 573, through micro-lens 583.
• At least one micro-latch can be actuated to a position that fixes the state of the micro-switch to the down position if electrical power is interrupted. In this exemplary embodiment, the micro-latch is in a state that would not impede the motion of the micro- switch 510 when it is in the up position.
• the appropriate arrangement of the micro-latch depends on the specific choice for the micro-actuator arrangement as described above.
• the micro-switch 510 includes at least one micro-mirror as the optical micro-element.
• the micro-mirror is a planar surface with a coating deposited on it.
• the coating is highly reflective to the wavelength of the optical beam.
• the coating material is gold, which is generally highly reflective for a wide range of wavelengths.
• Other coating material can be used, including multi-layer coating designed for specific wavelength(s) of the optical beam.
• a concave reflecting surface is used as the micro-optical element deflecting the optical beam.
• micro-lenses 581 and 582 are not necessary since the concave micro-mirror performs the focusing task of the micro-lenses 581 and 582.
• the micro- mirror is arranged so that an incident optical beam that is perpendicular to the direction of the motion of the micro-actuator is deflected into another direction that is also perpendicular to the direction of the motion of the micro-actuator.
• This embodiment can also be implemented using micro-lenses 581 and 582.
• the implementation of the preferred embodiment depicted in Figure 5 has the micro-lenses located on the other side of the fiber holders from the fiber input.
• the micro-lenses in the embodiment exemplified in Figure 5, as well as in the embodiments depicted later in the disclosure can be placed anywhere between the fiber holder and the corresponding optical micro-element.
• the invention herein disclosed can also be implemented in embodiments using plural optical micro-switches to control the routing of optical beams. For example, an array of M by N (including M or N being equal to 1) micro-switches can be used to control the routing of the optical beam(s).
• the arrangement of the fibers, the micro-lenses (if used), and the optical micro-element is such that the deflected beam is still efficiently collected into the target fiber during the motion of the optical microelement from the mechanically tensed situation to where the micro-latch contacts the micro-element (or the micro-actuator) and, thus maintains the mechanically tensed state.
• Figure 6 shows a schematic of a preferred embodiment according to the present invention wherein a two by two array of optical micro- switches are used to control the routing of optical beams.
• a micro-switch 610 in the up position routs an optical beam 600 delivered from an optical fiber 661.
• the fiber 661 is held in place by a fiber holder 671 that has a micro-lens 681 placed between the fiber 661 and the micro-switch 610.
• the micro-switch 610 in the up position routs the optical beam 600 to optical fiber 662, which is held in place by holder 672, through micro-lens 682.
• micro- switch 610 If the micro- switch 610 is in the down position, then it routs the optical beam 600 to optical fiber 663, which is held in place by holder 673, through micro-lens 683.
• At least one micro- latch as described above, can be actuated to a position that fixes the state of the micro-switch to the down position if electrical power is interrupted.
• the micro-latch is in a state that would not impede the motion of the micro-switch 610 when it is in the up position.
• the appropriate arrangement of the micro-latch depends on the specific choice for the micro-actuator arrangement as described above.
• micro-switch 610 includes at least one micro-mirror as the optical micro-element.
• the micro-mirror is a planar surface with a coating deposited on it.
• the coating is highly reflective to the wavelength of the optical beam.
• the coating material is gold, which is generally highly reflective for a wide range of wavelengths.
• Other coating material can be used, including multi-layer coating designed for specific wavelength(s) of the optical beam.
• a concave reflecting surface is used as the micro-optical element deflecting the optical beam.
• This embodiment differs from that of Figure 6 in using a concave reflective micro-mirror instead of a plane reflective micro-mirror.
• micro-lenses 681 and 682 are not necessary since the concave micro-mirror performs the focusing task of the micro-lenses 681 and 682.
• the micro-mirror is arranged so that an incident optical beam that is perpendicular to the direction of the motion of the micro-element is deflected into another direction that is also perpendicular to the direction of the motion of the micro-element.
• the embodiments of the invention using plural optical micro- switches can be implemented using a mixture of planar and concave mirrors as the at least one optical micro-elements included in each micro- switch.
• one of the micro-elements can be implemented as a planar micro-mirror and another micro-element can be implemented as a concave micro-mirror, with the appropriate choice for providing micro-lenses.
• the implementation of the invention can be extended to a two dimensional arrangement of M by N micro-switches where at least one of M and N is greater than 2.
• the present invention can also be implemented in two dimensional geometries using plural rows of micro-switches wherein at least two of the rows have different number of micro- switches.
• the invention can be implemented using five micro-switches arranged so that a first row has 3 micro-switches and a second row has two micro-switches.
• the invention herein disclosed is not limited in its implementation to the M by N rectangular equidistant distribution of optical micro- switches. Rather, the invention can be implemented using different geometries for the arrangement of the optical micro-switches including, but not limited to, rectangular arrays with different distances between at least two of the micro- switches, triangular, pentagonal, and hexagonal arrangement of micro-switches.
• the present invention can also be implemented using other imaging components in addition to, or instead of, the micro-lenses to direct the optical beams to the fibers.
• the preferred embodiments of the present invention implemented the router so that only when there is a power interrupt does the micro-latch contact the optical micro-element (or the micro-actuator) and, thus, make the optical micro-optical element hold its state.
• the micro-latch is arranged to contact the optical micro-element (or the micro-actuator, or both) when the micro-spring is in the tensed condition and, thus, electrical power may be intentionally removed according to the signals of Fig. 4(B) without affecting the state of the optical micro-element.
• the electrical power is turned back on according to the signals of Fig. 4(A) just before the micro- switch is to be intentionally driven to the up (mechanically quiescent) state.

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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)

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• 2001
  • 2001-01-03 WO PCT/US2001/000122 patent/WO2001050172A2/en active Search and Examination
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