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
  • G02F1/01—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 
  • G02F1/11—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 acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves
• • 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 
  • G02F1/09—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 magneto-optical elements, e.g. exhibiting Faraday effect
  • G02F1/092—Operation of the cell; Circuit arrangements
• • 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 
  • G02F1/0136—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  for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation

Definitions

• the invention relates to a method for changing the polarization state of light with a magnetically uniaxial crystal which changes into a single-domain state under the action of an external magnetic field pulse, light passing through predetermined regions of the crystal, and to a device for carrying out such a method.
• the subject of the invention is therefore methods and devices for changing the polarization of light beams and subsequently for changing the direction, the intensity and the like. More of these light beams, as are used in optical communication systems, information processing, displays etc.
• MEMS microelectromechanical systems
• acoustic-optical liquid crystalline
• electronically switchable Bragg gmtings Bragg grids
• bubblejets bubblejets
• thermo-optical interferometric
• thermo-capillary thermo-capillary
• electro-holographic and magneto-optical systems Numerous types of optical switches have been developed, including microelectromechanical systems (MEMS), acoustic-optical, liquid crystalline, electronically switchable Bragg gmtings (Bragg grids), bubblejets (bubble systems), thermo-optical, interferometric, thermo-capillary, electro-holographic and magneto-optical systems.
• MEMS microelectromechanical systems
• acoustic-optical liquid crystalline
• electronically switchable Bragg gmtings Bragg grids
• bubblejets bubblejets
• thermo-optical interferometric
• thermo-capillary thermo-capillary
• electro-holographic and magneto-optical systems thermo-opti
• Electro-optical systems have comparatively much shorter switching times; for example, the switching time of the new electro-holographic switches is only approx. 10 ns. But these circuits need permanent energy supply, at least in one state. In addition, the insertion loss of electroholographic switches is quite high, namely around 4-5 dB.
• Magneto-optical systems open up the possibility of combining short switching times and low insertion loss with the so-called “latching” mode of operation (see above).
• a multistable polarization rotator is described. Stable states in this Rotators are predetermined by inhomogeneities on the surfaces of orthoferritic platelets that cover the domain walls (DWs) Hold layers, guaranteed. Transitions between these stable states result from the shifting of the domain walls between these positions and take place without the creation of new domains. The time required for these transitions is approximately 100 ns, which means that they are several thousand times faster than for other optical switches of the "latching" type. However, the aperture of the switch is considerably restricted. The amplitude of the driver magnetic field is fairly small, which is why DWs can only travel at comparatively small distances.
• the object of the invention is to reduce the restrictions on the aperture of the switch.
• this is achieved in that a magnetic field pulse with a magnetic field strength (H) is applied to the crystal, in which the crystal does not remain in the signal domain state after the end of the pulse, but in a defined, from the direction of the applied Magnetic field returns certain multi-domain state.
• H magnetic field strength
• This increases the aperture of the switch by using higher amplitude magnetic field pulses.
• the aperture is defined by the zone in which magnetic pulses alternate. In the present invention, this zone represents the domain structure that occurs after the magnetic pulse is turned off. In orthoferrites, relatively large domains occur, which means that large switch apertures can also be reached.
• Orthoferrites have a rectangular hysteresis function.
• the coercive force of the Orthoferrite is quite high, it is a few kilo-oersted (kOe).
• the force required to overcome the coercive force generation 'high magnetic fields requires large energy input (this factor is particularly important for construction of densely packed switch matrices of importance) and can also increase the inductance of the scheme lead to, which increases the switching times.
• inhomogeneities on the crystal surface are used, which fix the domain walls in predetermined positions. If the distance between the inhomogeneities is small, or if thin orthoferrite flakes are used, the DW's move continuously from one dissimilarity to another.
• the last refers to the thickness »100 ⁇ m, used for polarization rotation in the visible and near infrared spectrum range. It was found that with thicker patterns, namely at> 1.2 mm thick yttrium orthoferrite crystals, which are responsible for 45 ° polarization rotation on the wavelengths> 1.3 ⁇ m are used, other situation is.
• the magnetization directions in certain crystal areas are changed to opposite:
• the DWs are oriented perpendicular to the direction of the crystallographic ⁇ -axis, see Fig. 1.
• the magnetizations are positive in the upper and lower domains and negative in the middle domains (Fig. La).
• a magnetic field pulse of negative polarity now acts on the crystal. If the amplitude of the pulse is approximately H s , the crystal is magnetized to the single domain state, Fig. Ib. After the end of the pulse, the crystal is divided into the domains, Fig. Lc.
• the polarization of the rays that pass through area 1 is “+” (that is, the direction of polarization has rotated clockwise) and the polarization of the rays that pass through area 2 is “-” "(the direction of polarization has rotated counterclockwise).
• a magnetic field pulse of negative polarity is applied, the polarization of the two beams will be “minus” during the pulse.
• the polarization of beams 1 and 2 will accordingly become “-” (for 1) and "+” (for 2
• the application of a magnetic field pulse of positive polarity leads to the new distribution: "+” and “+” and after the termination of this pulse the state "+” and "-” is created again.
• the polarity and the duration achieve a desired polarization distribution or combination at selected time intervals.
• Patent No. 408,700 uses irregularities (such as scratches) on the crystal surface through which the light rays pass to fix the DWs. These inhomogeneities on the surface cause light scattering, which is particularly troublesome when such crystals are used in attenuators.
• the inhomogeneities are applied to the side surface or the crystal.
• Fig. 2 shows such inhomogeneities in the form of scratches or scratches on the side surface of a rotator. The direction of the scratches or scratches is perpendicular to the crystallographic ⁇ -axis and parallel to the planes of the DWs.

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• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

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• 2002
  • 2002-02-12 AT AT0021602A patent/AT411852B/de not_active IP Right Cessation
• 2003
  • 2003-02-12 KR KR10-2004-7012476A patent/KR20040089623A/ko not_active Withdrawn
  • 2003-02-12 CA CA002475203A patent/CA2475203A1/en not_active Abandoned
  • 2003-02-12 CN CNB038037858A patent/CN100397148C/zh not_active Expired - Fee Related
  • 2003-02-12 WO PCT/AT2003/000042 patent/WO2003069395A2/de not_active Ceased
  • 2003-02-12 AU AU2003206487A patent/AU2003206487A1/en not_active Abandoned
  • 2003-02-12 RU RU2004127230/28A patent/RU2303801C2/ru not_active IP Right Cessation
  • 2003-02-12 EP EP03704088A patent/EP1474722A2/de not_active Withdrawn
  • 2003-02-12 PL PL03370581A patent/PL370581A1/pl not_active Application Discontinuation
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  • 2003-02-12 JP JP2003568460A patent/JP2005517977A/ja active Pending
  • 2003-02-12 US US10/504,130 patent/US7158301B2/en not_active Expired - Fee Related
• 2004
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Non-Patent Citations (1)

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