WO2001059515A2 - Commutateur optique - Google Patents

Commutateur optique Download PDF

Info

Publication number
WO2001059515A2
WO2001059515A2 PCT/CA2001/000134 CA0100134W WO0159515A2 WO 2001059515 A2 WO2001059515 A2 WO 2001059515A2 CA 0100134 W CA0100134 W CA 0100134W WO 0159515 A2 WO0159515 A2 WO 0159515A2
Authority
WO
WIPO (PCT)
Prior art keywords
polarization
light signal
signal
polarized light
cell
Prior art date
Application number
PCT/CA2001/000134
Other languages
English (en)
Other versions
WO2001059515A3 (fr
Inventor
Michael Gartner
Original Assignee
Opticom International Ltd.
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
Application filed by Opticom International Ltd. filed Critical Opticom International Ltd.
Priority to AU33520/01A priority Critical patent/AU3352001A/en
Publication of WO2001059515A2 publication Critical patent/WO2001059515A2/fr
Publication of WO2001059515A3 publication Critical patent/WO2001059515A3/fr

Links

Classifications

    • 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
    • G02F1/315—Digital deflection, i.e. optical switching based on the use of controlled internal reflection
    • 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 
    • G02F1/13—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 liquid crystals, e.g. single liquid crystal display cells
    • 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 
    • G02F1/13—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 liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1326—Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
    • 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
    • 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
    • G02F1/3137—Digital deflection, i.e. optical switching in an optical waveguide structure with intersecting or branching waveguides, e.g. X-switches and Y-junctions
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/07—Polarisation dependent

Definitions

  • This invention relates to switches for routing light signals carrying information. More particularly, the present invention relates to an optical switch and a method for routing light beams between different ports.
  • fiber optic networks do not exhibit electromagnetic interference or radio frequency radiation, resulting in a negligible impact on the surrounding environment. Likewise, fiber optic networks are less susceptible to external sources of electromagnetic interference or radio frequency radiation .
  • a fiber optic network In order for the potential fiber optic networks to be fully realized, a fiber optic network must ideally have the ability to route light signals from the point of initial transmission to the point of final destination.
  • the prior art devices to date for redirecting light in a fiber optic network have been classified into two broad areas, namely (i) opto-electrical switches and (ii) opto-mechanical switches .
  • Opto-electrical switches do not directly switch light signals, but rather convert the light signals to an electrical signal and then switch the electrical signal, similar to the manner in which electrical signals have been switched in the past. After the electrical signal has been switched, the opto-electrical switches then reconvert the electrical signals back to a light signal, which can continue along the fiber optic network.
  • Opto- electrical switches are fairly reliable because they utilize the same technology that has been used in the past to switch electrical signals.
  • opto-electrical switches suffer from the disadvantage that the bandwidth of the system is limited by the electrical switching of the electrical signals.
  • the bandwidth of the system is also constrained by the ability of the converters to convert the light signal to an electrical signal and then convert the electrical signal back to a light signal after the electrical signals have been switched. Therefore, a fiber optic network which utilizes opto-electrical switches has a bandwidth which is constrained by the opto-electrical switch. This may also result in under utilization of a majority of the fiber optic network.
  • Opto-mechanical switches use a series of mechanical mirrors to redirect the light signals .
  • the mechanical mirrors reflect the light signals and can be mechanically moved to route the light signals towards their final designation.
  • opto- mechanical switches can redirect light signals without converting them to electrical signals
  • optomechanical switches are constrained by the accumulative light loss resulting from the mechanical mirrors. This accumulative light loss limits the size of the switch matrix. In particular, it has been difficult to assemble a switching matrix larger than 32 ports. Clearly, this matrix size limitation severely restricts the number of , applications in the fiber optic telecommunication industry that can use this technology.
  • the mechanical switches used in the opto-mechanical switches require large quantities of power to operate and frequently require repair in view of the mechanical parts that are moving to move the mirrors. This further affects the reliability of the opto-mechanical switches in large commercial operations.
  • the prior art opto-mechanical switches suffer from the disadvantage that there is an accumulative light loss, which decreases the effectiveness of the opto-mechanical switches and limits the size of the opto-mechanical switch. Furthermore, opto-mechanical switches require large quantities of power and frequent repair. While opto-electrical switches can be used to overcome some of the disadvantages of the opto-mechanical switches, opto-electrical switches suffer from the disadvantage that they severely limit the bandwidth of the fiber optic network, leaving other parts of the fiber optic network underutilized.
  • an object of this invention to at least partially overcome the disadvantages of the prior art. Also, it is an object of this invention to provide an optical switch which can switch or route light signals without converting the light signals into electrical signals. It is also an object of this invention to provide an optical switch which can redirect light signals without suffering a large accumulative light loss or requiring mechanical movement of mirrors, which consume large amounts of power and require repair.
  • the present invention provides an optical switch for routing a light signal to a first port or a second port, said optical switch comprising: a splitter cell for splitting the light signal into a first polarized signal having a first polarization and a second polarized light signal having a second polarized signal; a polarization changing device for changing the polarization of the first polarized light signal from the first polarization to the second polarization and for changing the polarization of the second polarized light signal from the second polarization to the first polarization when a light signal is applied to the polarization changing device and for not changing the polarization of the first light signal or the second polarization signal when a second signal is applied to the polarization changing device; a recombiner cell for recombining the first polarized light signal and the second polarized light signal into a recombined light signal; wherein the recombined light signal will travel toward the first port when the first signal is applied to the polarization changing device
  • the present invention provides a method of routing light signals, said method comprising steps of: separating the light signal into a first polarized light signal having a first polarization and a second polarized light signal having a second polarization; passing the first polarized light signal and the second polarized light signal through a polarization changing device which changes the first polarization to the second polarization and changes the second polarization to the first polarization when a first signal is applied to the polarization changing device and does not change the polarization of the first polarized light signal and the second polarized light signal when a second signal is applied to the polarization changing device; recombining the first polarized light signal having the first polarization and the second polarized light signal having the second polarization signal after they have passed through the polarization changing device into a recombined light signal; and applying the first signal to the polarization changing device to route the recombined light signal in a first direction and not applying the second signal to the
  • one advantage of the present invention is that the light signals can be switched or routed without converting the light signals into electrical signals.
  • the optical switch according to the present invention provides a large bandwidth, and is not limited by the bandwidth of an electrical switch or a conversion device which converts the light signals to and from electrical signals, as is the case with opto-electrical switches .
  • a further advantage of the present invention is that, because the light signals are being switched or routed without the light signals being converted to electrical signals, the optical switch according to the present invention will switch the light signals at about the same speed at which the light signals travel through the other components of the optical fiber network. In other words, the other parts of the optical fiber network will not be underutilized.
  • the optical switch according to the present invention has no moving parts. Rather, the optical switch can switch the light signals by changing the polarization of components of the light signal by means of a liquid crystal. Accordingly, this lack of moving parts decreases the likelihood that the optical switch will require repair, and further results in a corresponding increase in the reliability of the optical switch.
  • a still further advantage of the present invention is that the optical switch can redirect light signals which may comprise light at different wavelengths. This is particularly useful where the light signal has been subject to wave division multiplexing and the light signal comprises a plurality of individual light signals, each individual light signal at a distinct wavelength.
  • Figure 1 shows a schematic side view of a 2x2 optical switch according to one embodiment of the present invention.
  • Figure 2a shows the optical switch shown in Figure 1 with a light signal entering through one port and the polarization changing device not changing the polarization of the polarized light signals;
  • Figure 2b shows the optical switch shown in Figure 1 with a light signal entering through one port and the polarization changing device changing the polarization of the polarized light signals;
  • FIG. 3a shows the optical switch shown in
  • Figure 1 with a light signal entering through a port different than the port illustrated in Figure 2a and the polarization changing device not changing the polarization of the polarized light signals;
  • Figure 3b shows the optical switch shown in Figure 1 with a light signal entering through a port different from the port illustrated in Figure 2b and the polarization changing device changing the polarization of the polarized light signals;
  • Figure 4 shows a 4x4 optical switch comprising 16 2x2 optical switches shown in Figure 1.
  • Figure 1 is a schematic drawing of a side view of a 2x2 optical switch, shown generally by reference numeral 10, according to one embodiment of the present invention.
  • the embodiment of the optical switch 10 shown in Figure 1 has two input ports I a , I B and two output ports O A , O B . It is understood that the invention could operate with a single input port, either I A or IB.
  • the optical switch 10 further preferably comprises collimating lenses 8A, 8B, 8A' , 8B' for collimating the light signals L s as they enter and exit the optical switch 10.
  • collimating lenses 8A, 8B, 8A' , 8B' are not necessary for the proper operation of the invention.
  • the optical switch 10 further comprises a splitter cell 11 and a recombining cell 12.
  • the splitter cell 10 splits or separates the light signals L s (shown in Figures 2a and 2b) entering through either input port I A or I B .
  • the splitter cell 11 will split the light signal L s into two separate polarized light signals L SPA and L SPB (shown in Figures 2a and 2b) having different polarizations .
  • the splitter cell 11 directs the polarized light signal L SPA , L SPB along either the first path 21 or the second path 22.
  • the splitter cell 11 may direct the first polarized light signal L SPA onto the first path 21 and may direct the second polarized light signal L S p B onto the second path 22.
  • each path 21, 22 comprises a permanent mirror 24, 26, respectively, to direct the polarized signals.
  • the first path 21 and second path 22 will then intersect at the recombining cell 12.
  • the recombining cell 12 recombines the two polarized signals L S p A , L S p B into a recombined light signal L ⁇ c comprising both polarizations.
  • the recombined polarization signal will then travel through one of the output ports 0 A , 0 B in a manner described below.
  • the splitter cell 11 comprises a first polarization cell 15.
  • the first polarization cell 15 is transparent to the portion of the light signals L s having a first polarization and the first polarization cell 15 reflects the portion of the light signals L s having a second polarization. In this way, the first polarization cell 15 permits a first polarized light signal L SPA having a first polarization to travel through the first polarization cell 15, but reflects a second polarized light signal L SPB having a second polarization.
  • the first polarization cell 15 will both separate the light signal L s into a first polarized light signal L S p A and a second polarized signal L SPB , having first and second polarizations, respectively, as well direct the polarized light signals L S p A and L SPB onto the first light path 21 and the second light path 22, respectively.
  • the first polarization cell 15 comprises a plate of glass having liquid crystal molecules normal to the plate of glass which causes the first polarization cell 15 to be transparent to the portion of the light signals L s which is horizontally polarized.
  • the horizontal polarization cell 15 will reflect the portion of the light signal L s which is vertically polarized.
  • other types of polarization cells including polarization cells which are transparent to vertically polarized light signals L s and reflect horizontally polarized light signals L s , could also be used.
  • the recombining cell 12 comprises a second polarization cell 16.
  • the second polarization cell 16 will be transparent to polarized light signals L SPA ⁇ L SPB having one type of polarization, such as the first polarization, and will reflect polarized light signals L SPA/ L SPB having another type of polarization, such as the second polarization.
  • the second polarization cell 16 will reflect one polarized light signal L SPA , L SP B and transmit the other polarized light signal LSPB ⁇ L SPA , depending on their polarization, to recombine the first and second polarized light signals L SP ⁇ L SPB into the recombined light signal l * sc-
  • the second polarization cell 16 will also have liquid crystal molecules normal to the plate of glass and will therefore also be transparent to horizontally polarized light signals and reflect vertically polarized light signals.
  • the first and second polarization cells 15, 16 could be formed from a single plate of glass.
  • the polarization cells 15, 16 could be formed from a single polarization cell comprising a single uncut plate of glass.
  • the light signal L s strike the first polarization cell 15 at an angle of incidence of about 70° with respect to the normal.
  • the first and second polarized signals L S p A , L SPB have an angle of incidence onto the second polarization cell 16 of about 70° with respect to the normal.
  • the first and second polarized signals L S PA ⁇ LSPB have the same angle of incidence onto the second polarization cell 16 and at about the same longitudinal position on the second polarization cell 16. It is also preferable that the optical distance of the first light path 21 be substantially equivalent to the optical path of the second light path 22.
  • the optical switch 10 also comprises a polarization changing device, shown generally by reference numeral 30.
  • the polarization changing device 30 will change the polarization of the polarized light signals L S p A , L S p B travelling through the first path 21 and the second path 22.
  • the polarization changing device 30 comprises a first liquid crystal cell 31 along the first path 21 and a second liquid crystal cell 32 along the second path 22.
  • the first liquid crystal cell 31 rotates the polarization of the polarized light signal L S p A in the first path 21 by about 90° when the first signal Si is applied to the first liquid crystal cell 31.
  • a second signal S 2 is applied to the first liquid crystal cell 31
  • the polarization of the first polarized signal L SPA travelling along the first path 21 will not be affected.
  • the second liquid crystal cell 32 operates in a similar manner to the first liquid crystal cell 31 by changing the polarization of the polarized light signal L SPB travelling along the second path 22 and not changing the polarization when the second signal S 2 is applied.
  • the liquid crystal cells 31, 32 may have a stable "off state” when no voltage or signal is applied. In this stable “off state”, the liquid crystal cells 31, 32 would not change the polarization of the polarized light signals L S PA, L SPB when no voltage or signal is applied. In this case, by simply not applying the first signal Si, the polarized light signals L S p A , L S p B will not be changed. However, in some cases, the liquid crystal cells 31, 32 will require a second signal S 2 , which may be a reverse voltage to the first signal Si, to return the liquid crystal cells 31, 32 to a state where the polarized light signals L SPA ⁇ L SPB passing through the liquid crystal cells 31, 32 are not being changed. Accordingly, when the liquid crystal cells 31, 32 have a stable "off state", the second signals S 2 can be considered an "off” signal or "0" signal equivalent to the first signal Si not being applied.
  • the first signal Si and the second signal S 2 are generated and applied by a supervisory control module 40.
  • the supervisory control module 40 determines whether or not to apply the first signal Si or the second signal S 2 based on either an address header or a frequency modulation identification of the light signal L s .
  • the address header and frequency modulation identification of the light signal L s indicate the final destination of the light signal L s , as is known in the art.
  • the optical switch 10 and the supervisory control module 40 together form a system for routing light signals, shown generally by reference numeral 90 in Figure 1. The operation of the optical switch 10 will now be discussed with respect to Figures 2a and 2b.
  • the splitter cell 11 will be considered as comprising a horizontal polarization cell 15 which is transparent to the portion of light signals L s having a horizontal polarization and reflective to the portion of light signals L s having a vertical polarization.
  • the recombining cell 12 will be considered as comprising a horizontal polarization cell 16 which is also transparent to horizontally polarized light and reflective to vertically polarized light.
  • horizontal polarization cells 15, 16 have been selected only for the purposes of explaining the operation of one embodiment of the invention and other types of splitter cells 11 and recombining cells 12, as well as other types of polarization cells 15, 16 can be used.
  • a light signal L s is shown entering through input port I B .
  • Light signal L s is shown by a solid line and reference numeral L s .
  • the light signal L s will pass through the collimating lens 8B and then reach the splitter cell 11.
  • the splitter cell 11 will split the light signal L s into a first polarized light signal L S A travelling along the first path 21 and a second polarized light signal L S p B travelling along the second light path 22.
  • the splitter cell 11 is considered, for the purposes of illustration, to be a horizontal polarization cell 15, the portion of the light signal L s which passes through the splitter 11 will have a horizontal polarization and in this case will be the first polarized light signal L SPA travelling on the first light path 21.
  • the first polarized light signal L SPA is illustrated in Figure 2a as being horizontally polarized by the dash dot dash line " - ".
  • the horizontal polarization cell 15 will reflect the portion of the light signal L s having a vertical polarization
  • the second polarized light signal L S p B travelling in the second path 22 will be vertically polarized. This is illustrated by the dash plus dash line " + " shown in Figure 2a.
  • the second signal S 2 is being applied to the liquid crystal cells 31, 32 which together comprise the polarization changing device 30.
  • the polarization changing device 30 is not changing the polarization of the first polarized signal L S and the second polarized signal L SPB .
  • the first polarized signal L SPA will then travel along the first path 21 being reflected by the permanent reflecting surface 24 and the second polarization signal L SPB will travel along the second path 22 and be reflected by the permanent reflecting surface 26 and the polarization of both polarized light signals L SPA , L SPB will not be changed.
  • the first light path 21 and the second light path 22 intersect at the recombining cell 12.
  • the recombining cell 12 will be considered to be a horizontal polarization cell 16 which is transparent to horizontally polarized light and reflects vertically polarized light. Accordingly, the first and second polarized light signals L SPA , L SPB will meet at the second horizontal polarization cell 16.
  • the first polarized light signal L SPA which is horizontally polarized, will pass through the horizontal polarization cell 16, but the second polarized light signal L S B , which is vertically polarized, will be reflected by the horizontal polarization cell 16.
  • both the first polarized light signal L SPA and the second polarized light signal L SPB will travel in the same direction, thus recombining into the recombined light signal L S c-
  • the recombined light signal L S c is shown as a solid line as it has been recombined and comprises both a horizontally polarized portion and a vertically polarized portion.
  • the recombined light signal L sc will have properties similar to the light signal L s and carry the same information as the light signal L s .
  • the recombined light signal L sc will travel towards one of the output ports 0 A , 0 B , which in the example shown in Figure 2a is the output port 0 B . Accordingly, it is apparent that the recombining cell 12 will recombine the polarized signals L SPA , L SPB into the recombined signal L sc .
  • the recombined signal L S c will travel in a direction which is dependent on the relative polarizations of the polarized signals L SPA , L SPB , as well as the properties of the recombining cell 12.
  • the recombining cell 12 is a horizontal polarization cell 16 which is transparent to horizontally polarized light providing the result that the recombined light signal L sc will travel in the same direction as whichever polarized light signal L SPA , L SPB is horizontally polarized when the polarized light signals L SP C L SPB are recombined.
  • the first polarized light signal L SPA is horizontally polarized when the signals L S A, L SPB are recombined, the recombined light signal L sc will travel in the same direction as the first polarized light signal L S p A , which in this case is towards output port 0 B .
  • Figure 2b is similar to Figure 2a except that the first signal S x is being applied to the liquid crystal cells 31, 32, which together form the polarization changing device 30. Accordingly, in the example illustrated in Figure 2b, the polarization of the first and second polarized light signals L SPA ⁇ L SPB will change as they travel along the first and second light paths 21, 22.
  • the light signal L s again enters through input port I B and strikes the splitter cell 11.
  • the splitter cell 11 will split the light signal L s into the first polarization signal L SPA and the second polarization signal L SPB - AS we are continuing to consider the beam splitter 11 to be a horizontal polarization cell 15, the first polarized light signal L SPA. - which passes through the beam splitter 11, will be initially horizontally polarized and the second polarized light signal L S p B , which is reflected by the horizontal polarized cell 15, will be initially vertically polarized.
  • the liquid crystal cell 31 As the first polarized signal L SPA travels along the first path 21, it will encounter and interact with the liquid crystal cell 31, which, as the first signal Si is being applied, will change the polarization of the first polarized light signal L SPA - AS, in this case, the first polarized light signal L S p A is initially horizontally polarized, the liquid crystal cell 31 will change the polarization of the first polarized light signal L S p a to be vertically polarized. This is illustrated in Figure 2b by the dash dot dash line changing into the dash plus dash line.
  • the polarization of the second polarized light signal SPA will change from being vertically to horizontally polarized. This is illustrated in
  • Both the first polarized light signal L S p A , which is now vertically polarized, and the second polarized light signal L SPB , which is now horizontally polarized, will continue along the first path 21 and the second path 22, respectively, until they intersect at the recombining cell 12.
  • the recombining cell 12 is considered to be a horizontal polarization cell 16 for this illustration, the second polarized light signal L SPB , which is horizontally polarized, will pass through the recombining cell 12.
  • the first polarized light signal L SPA which is now vertically polarized will be reflected by the recombining cell 12 providing the result that the first polarized signal L SPA and the second polarized signal L S p B will recombine into the recombined light signal L S c, similar to Figure 2a.
  • the second polarized light signal L SPB is now horizontally polarized, the recombined light signal L sc will travel in the same direction as the second polarized light signal L S p B , namely towards output port 0 A .
  • optical switch 10 will operate with only one input port, such as input port I B . In this case, all light signals L s would enter through input port I B and exit through either output port 0 A or output port 0 B , depending on whether the first signal Si or the second signal S 2 is applied to the liquid crystal cells 31, 32. However, the optical switch 10 can also operate with a second input port I A , as illustrated in Figures 3a and 3b.
  • the light signal L s entering through input port I A will be switched or routed to output port 0 A or output port 0 B in a similar manner to which light signal L s entering through input port I B was switched or routed to output port 0 A or output port 0 B , as described above with respect to input port I B .
  • the splitter cell 11 splits the light signal L s into the first polarized signal L S p A and the second polarized signal L S p B .
  • the first polarized signal L S p A is being reflected from the splitter cell 11, and assuming the splitter cell 11 is a horizontal polarization cell 15, the first polarized light signal L S p A will be initially vertically polarized, as shown by the dash plus dash line.
  • the second polarized light signal L SPB which passes through the splitter cell 11, will be horizontally polarized, as shown by the dash line.
  • the second signal S 2 is being applied in the example shown in Figure 3a, the polarization of the polarized light signals L SV ⁇ , L SPB will not be changed.
  • L SPB will reco bine into the recombined light signal L sc .
  • the recombined light signal L S c will continue in the same direction as the horizontally polarized light signal, which, in the example shown in Figure 3a, is the second polarized light signal L SPA toward output port 0 A . Accordingly, when the second signal S 2 is applied to the liquid crystal cells 31, 32, and the light signal Ls enter through input port I A , the recombined light signal L sc will travel towards and exit output port 0 A .
  • the recombined light signal L sc will travel in the same direction as whichever polarized light signal L SPA or Ls PB has a horizontal polarization.
  • the first polarized light signal L SPA is horizontally polarized
  • the recombined light signal L sc will travel towards output port 0 B .
  • the recombined light signal L S c will travel towards the first output port 0 A .
  • the recombined light signal L S c will travel towards the second output port 0 B .
  • the splitter cell 11 and the recombining cell 12 can split or recombine light signals L s entering through either input port I A or input port I B .
  • the splitter cell 11 and recombining cell 12 comprise horizontal polarization cells 15, 16, the horizontal polarization cells 15, 16 will have two opposed surfaces 15a, 15b, and 16a, 16b, respectively, as shown in Figure 1, upon which light signals L s can be incident. In this way, light signals L s can be inputted from both input port I A and input port I B and be switched by the optical switch 10.
  • the optical switch 10 can switch optical signals L s entering through both the input port I A and the input port I B simultaneously.
  • the switch 10 will operate as a toggle connecting light signals L s from input port I A , I B to output ports 0 A , 0 B or output ports 0 B , 0 A , depending on whether or not the second signal S 2 or the first signal Si is applied to the liquid crystal cells 31, 32.
  • the optical switch 10 is bi-directional in that light signals L s can also enter through the output ports 0 A , 0 B and be switched by the optical switch 10 to exit through one of the input ports I A/ I B - Accordingly, in this preferred embodiment, the input ports I A , I B and the output ports O , O B act as input/output ports I/0 A , I/0 B and input/output ports I/0 A » I/0 B' as shown in Figure 1.
  • Using the optical switch 10 in a bidirectional manner to send and receive optical signals 10 to input/output ports is particularly beneficial where a large amount of information is to be sent to and from two separate entities.
  • the optical switch 10 When light signals L s enter through input/output ports I/0 A ', I/O B' , the optical switch 10 will operate in a similar manner to that illustrated in Figures 2a, 2b, 3a and 3b, except in reverse in that the light signals L ⁇ will enter through the input/output ports I/O A ', I/0 B' and the recombined light signal L S c will exit through one of the input/output ports I/O a , I/0 B . Furthermore, the second polarization cell 16 will act to split the light signals L ⁇ entering through the input/output ports I/0 A , I/0 B into polarized light signals L SPA . L ⁇ PB which travel on the first and second light paths 21, 22.
  • the first polarization cell 15 will act to recombine the polarized light signals L SP , L SPB into a recombined light signal L sc which will travel towards one of the input/output ports I/0 A , I/0 B depending on whether the first signal Si or the second signal S 2 is being applied to the liquid crystal cells 31, 32. Accordingly, in this preferred embodiment, the first and second liquid crystal cells 31, 32 act in a bidirectional manner and the first and second polarized cells 15, 16 act as both a splitter cell 11 and a recombiner cell 16.
  • the light signals L s will enter the input ports I A , I B generally through a fiber optic network, such as through a fiber optic cable. Likewise, the recombined signals L sc will exit through output ports 0 A , O B to the fiber optic network, such as through another fiber optic cable.
  • the optical switch 10 it is possible to combine the optical switch 10 with other optical switches, including other optical switches identical to optical switch 10 so that the input and output do not come from and go to the fiber optic network, but rather other optical switches 10. In this way, a larger optical switch having more than two input ports I A , I B and two output ports 0 A , 0 B can be formed, as illustrated in Figure 4.
  • Figure 4 shows a 4x4 optical switch array, shown generally by reference numeral 100.
  • the optical switch array 100 comprises 16 2x2 optical switches 10, as shown in Figures 1, 2a, 2b, 3a, 3b and 4.
  • the optical switches 10 within the optical switch array 100 are arranged such that at least one input/output port I/0 A' , I/0 B ⁇ is operatively connected to an input/output port I/0 A , I/0 B of a second optical switch 10' .
  • at least one input/output port I/0 A , I/0 B will be operatively connected to the input/output port I/0 A -, I/0 B ' of a third optical switch 10''.
  • the optical switch 100 can switch light signals L s from input/output ports I 0 A, I 0 B, I 0 C, I 0 D to input/output ports I 0 A' , I 0 B' , I 0 C , I 0 D' .
  • the optical switch 100 will be controlled by sending the first signal Si and the second signal S 2 to each individual optical switch 10 within the optical switch array 100.
  • the first signal Si and the second signal S 2 to each of the optical switches 10 will be generated and applied by a supervisory control module 140 which controls the operation of optical switch 100.
  • a supervisory control module 140 which controls the operation of optical switch 100.
  • the supervisory control module 140 will determine to which optical switch 10 the first signal S x and the second signal S 2 should be applied based on either an address header or a frequency modulation identification of the light signal L s indicating which input/output port I 0 A' , IoB', IoC, I 0 D' of the optical switch array 100 the light signal L s should be switched to.
  • optical switch arrays larger than the 4x4 optical switch array 100 are also possible.
  • optical switch arrays of 16x16 and 256x256 have been used.
  • 2048x2048 optical switch arrays comprising a plurality of optical switches 10 are possible without significant light loss.
  • the light signal L s can include any type of light signal carrying any type of information.
  • the light signal L s can include information such as uncompressed video signals, either high definition or broadcast quality format, and switched mass data services up to OC 192 (10 gigabits per second) per input I A or I B .

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)
  • Liquid Crystal (AREA)

Abstract

L'invention se rapporte à un commutateur optique conçu pour acheminer des signaux lumineux et comportant une cellule de répartition et une cellule de recombinaison. Les signaux lumineux pénétrant dans le commutateur optique sont initialement divisés en deux signaux optiques polarisés de polarisation différente. Les deux signaux lumineux polarisés sont alors recombinés par la cellule de recombinaison et acheminés vers l'un des deux ports de sortie. Ce commutateur optique comporte également un dispositif de modification de la polarisation qui modifie la polarisation des deux signaux lumineux polarisés en fonction d'un signal de commande. Le signal lumineux recombiné sortant de la cellule de recombinaison se propage dans un sens correspondant à l'un des deux signaux lumineux polarisés en fonction de la polarisation de ces signaux lumineux polarisés. Lorsque le signal de commande destiné à modifier la polarisation de ces signaux lumineux polarisés est appliqué, le signal lumineux recombiné se propage vers l'un des deux ports de sortie. Ce commutateur optique peut fonctionner avec deux ports d'entrée et deux ports de sortie et il peut commuter des signaux lumineux entrant simultanément par les deux ports d'entrée, jouant ainsi le rôle de commutateur optique à bascule. Ce commutateur optique est également bidirectionnel de sorte que les ports de sortie peuvent jouer le rôle de ports d'entrée et que les ports d'entrée peuvent jouer le rôle de ports de sortie. Ce commutateur optique est un commutateur 2x2 mais il est possible de le combiner à d'autres commutateurs optiques similaires pour fabriquer des commutateurs optiques de dimension supérieure tels que des commutateurs optiques 4x4.
PCT/CA2001/000134 2000-02-08 2001-02-08 Commutateur optique WO2001059515A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU33520/01A AU3352001A (en) 2000-02-08 2001-02-08 Optical switch

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US50002600A 2000-02-08 2000-02-08
US09/500,026 2000-02-08

Publications (2)

Publication Number Publication Date
WO2001059515A2 true WO2001059515A2 (fr) 2001-08-16
WO2001059515A3 WO2001059515A3 (fr) 2002-05-10

Family

ID=23987725

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2001/000134 WO2001059515A2 (fr) 2000-02-08 2001-02-08 Commutateur optique

Country Status (2)

Country Link
AU (1) AU3352001A (fr)
WO (1) WO2001059515A2 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4335939A (en) * 1979-04-09 1982-06-22 Crosfield Electronics Limited Optical modulators and apparatus including such modulators
US4702557A (en) * 1983-07-29 1987-10-27 U.S. Philips Corporation Optical branching device using a liquid crystal
US4792212A (en) * 1986-09-30 1988-12-20 Itt Defense Communications, A Division Of Itt Corporation Liquid crystal switching device
EP0624812A1 (fr) * 1993-05-11 1994-11-17 Mitsui Petrochemical Industries, Ltd. Dispositif de modulation de la lumière à cristal liquide

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4335939A (en) * 1979-04-09 1982-06-22 Crosfield Electronics Limited Optical modulators and apparatus including such modulators
US4702557A (en) * 1983-07-29 1987-10-27 U.S. Philips Corporation Optical branching device using a liquid crystal
US4792212A (en) * 1986-09-30 1988-12-20 Itt Defense Communications, A Division Of Itt Corporation Liquid crystal switching device
EP0624812A1 (fr) * 1993-05-11 1994-11-17 Mitsui Petrochemical Industries, Ltd. Dispositif de modulation de la lumière à cristal liquide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
R.E.WAGNER ET AL.: "Electrically controlled optical switch for multimode fiber applications" APPLIED OPTICS, vol. 19, no. 17, 1 September 1980 (1980-09-01), pages 2921-2925, XP002187676 *

Also Published As

Publication number Publication date
WO2001059515A3 (fr) 2002-05-10
AU3352001A (en) 2001-08-20

Similar Documents

Publication Publication Date Title
US6539142B2 (en) System and method for actively aligning mirrors in an optical switch
CA2394936C (fr) Dispositif d'interconnexion en fonction de la longueur d'onde
CA2253752C (fr) Arrangement de commutation de signaux optiques en espace libre
US7088882B2 (en) Wavelength cross-connect
NL1005263C2 (nl) Optisch pakket-geschakeld transmissie-netwerk.
US7826697B2 (en) System and method for asymmetrical fiber spacing for wavelength selective switches
US5168535A (en) Integrated optic switch
JPH10511777A (ja) 導波型光クロスポイントスイッチ
US11516562B2 (en) Core selective switch and optical node device
US6618517B2 (en) Cascadable large optical cross-connect
US6947629B2 (en) 3D image feedback optical beam alignment
US6816296B2 (en) Optical switching network and network node and method of optical switching
US6418247B1 (en) Fiber optic switch and associated methods
EP1348988A2 (fr) Matrice de commutateurs optiques comprenant des séries de guides d'ondes planaires arrangées perpendiculairement
KR20020031353A (ko) 편광 게이트들을 이용하는 모든 광학 상호접속
US7057716B2 (en) White cell antenna beamformers
Kato et al. 10Gb/s photonic cell switching with hybrid 4× 4 optical matrix switch module on silica based planar waveguide platform
US6867920B2 (en) Optical beam-steering switching system having beam coupling control
WO2001059515A2 (fr) Commutateur optique
US20010033707A1 (en) System and method for optically switching/routing optical channels of any wavelength to any fiber
EP1096826A2 (fr) Méthode et dispositif de commutation optique
US20030185495A1 (en) Optical switching system
Himeno et al. Recent progress on silica-based optical switches and free-space optical switches
CA2363607A1 (fr) Commutateur optique

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase in:

Ref country code: JP