US3580664A - Transmission element for magneto-optical applications, particularly for the modulation of infrared radiation in the wavelength range between 1 and 20 microns - Google Patents

Transmission element for magneto-optical applications, particularly for the modulation of infrared radiation in the wavelength range between 1 and 20 microns Download PDF

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Publication number
US3580664A
US3580664A US789506A US3580664DA US3580664A US 3580664 A US3580664 A US 3580664A US 789506 A US789506 A US 789506A US 3580664D A US3580664D A US 3580664DA US 3580664 A US3580664 A US 3580664A
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microns
transmission element
radiation
wavelength range
exceeding
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US789506A
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English (en)
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Piet Frans Bongers
Giulio Zanmarchi
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US Philips Corp
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US Philips Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/0009—Materials therefor
    • G02F1/0036—Magneto-optical materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/40—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials of magnetic semiconductor materials, e.g. CdCr2S4
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S359/00—Optical: systems and elements
    • Y10S359/90—Methods

Definitions

  • Trifari ABSTRACT A novel magneto-optical transmission element consisting of a substrate transparent to radiation in the wavelength range between 1 and 20 microns having thereon a monocrystalline or polycrystalline layer of a material having a spinel structure, a magnetic permeability, in vacuo, #0 B/H exceeding 1.2 at temperatures lower than the Curie point, i.e. the material is either ferromagnetic or ferrimagnetic, a resistivity at the Curie point exceeding 100 ohm-cm and a chemical composition having the formula A C52,, Z being selenium, sulfur, or telluorium and A being in general a divalent metal or complex, preferrably cadmium.
  • the transmission element may also serve as a memory element in which information therein can be read out by determining the sign of the remanent magnetization thereof by means of polarized infrared radiation.
  • the invention relates to a transmission element for magneto-optical applications, particularly for the modulation of infrared radiation in the wavelength range between l and 20 microns.
  • Transmission elements as meant here consist of one or more single crystals or of a monocrystalline or polycrystalline layer on a substrate transmitting infrared radiation.
  • the above-mentioned application is based on the ability of the substance of which the transmission element in question consists to rotate the plane of polarization of an incident linearly polarized electromagnetic radiation under the influence of a magnetic field which has a component in the direction of propagation of the radiation. The rotation is known as Faraday-rotation.”
  • the value of the Faraday-rotation ((D) is cxpremed here in the number of degrees of rotation of the plane of polarization per cm. of path length of the radiation covered in the transmission element, when the latter is magnetized to saturation in a magnetic field parallel to the direction of radiation.
  • magnetic materials which readily transmit the radiation to be modulated.
  • Said magnetic materials are to be understood to means herein materials which, at temperatures lower than a critical temperature (Curie point), characteristic of the material in question, are ferromagnetic or ferrimagnetic.
  • P D the so-called figure of merit
  • the so far best known materials for transmission elements to be ,used for the modulation of infrared radiation having a wavelength between 1 and 6 microns are yttrium-iron garnet, Y Fe O, and the compounds which can be derived therefrom, inter alia by the partial replacement of iron by gallium. These substances are ferrimagnetic at room temperature. They are preferably used in the form of single crystals. Although the Faraday rotation of these garnets increases when the wavelength decreases below a value of 1 micron, this advantage is undone by a radiation absorption which also increases strongly, so that the figure of merit assumes low values. For wavelengths exceeding 6 microns, both the rotation is small and the absorption coefficient is large so that garnets are useless at those wavelengths for the applications in view.
  • the invention relates to a transmission element for the modulation of infrared radiation in the wavelength range between I and 20 microns.
  • This transmission element must satisfy each of the following conditions:
  • the crystals in question can be obtained, for example, by synthesis.
  • crystals of the compounds cadmium chromium selenide, CdCr Se may be prepared in such a manner that cadmium selenide, CdSe, and chromium selenide, Cr Se are dissolved in anhydrous, molten cadmium chloride and the resulting solution is slowly cooled for example, at a rate of l-5 C. per hour.
  • the cadmium chromium selenide is one of the most important representatives of the group of substances which have the above-defined chemical composition and the crystals of which are suitable for the formation of transmission elements according to the invention. It is ferromagnetic at temperatures lower than approximately FIG.
  • la is a graph which shows the variation of the absorption coefficient, a (in cm"), of a crystal of CdCr,Se as a function of the wavelength A (in microns) in the wavelength range of approximately l2l microns, at a temperature of K. It was found that the absorption coefficient is low throughout the wavelength range of approximately 1 to 21 microns, with a highest value not exceeding approximately 13 cm. in the wavelength range between 6 and 18 microns. From the substantially constant value of a in the last-mentioned wavelength range it may be concluded that the measured absorption is mainly to be ascribed to the presence of chemical and physical inhomogeneities in the crystal so that the absorption measured in a substantially homogenous crystal will be considerably lower than the one actually measured.
  • FIG. lb shows corresponding graphs for a crystal of yttrium-iron garnet, Y Fe O, at 90 K and at 300 K. It may be seen that, although this crystal has a still considerably lower absorption at wavelengths. between approximately LI and 6 microns than the crystal of CdCr Se to which FIG. 1a relates, the absorption of the yttrium-iron garnet crystal at wavelengths exceeding 6 microns increases so strongly as a function of the wavelength that the use of the said material is restricted to wavelengths of 1.1-6 microns.
  • the graph shown in FIG. 3 represents the Faraday-rotation of the CdCr,Se crystal considered, as a function of the wavelength, within the wavelength range of 45-18 microns, at a temperature of 90 K. It is seen from this FIG. that at a wavelength of approximately 7.8 microns, the Faraday-rotation of the CdCr,Se crystal in question (at 90 K.) changes its sign, so that the crystal at that temperature cannot be used for modulating radiation having a wavelength between approximately 7.5 and 8 microns.
  • FIGS. 4 and 5 shown graphs for the figure of merit of the present CdCr,Se crystal as a function of the wavelength, also at a temperature of 90 K.
  • Transmission elements according to the invention may also be used as memory elements which are read by determining the sign of the remanent magnetization thereof by means of polarized infrared radiation.
  • Z is a member of the group consisting of S, Se and Te.
  • a process of storing and retrieving information from a memory element consisting of a substrate transparent to radiation having a wavelength between 1 and 20 microns having a layer thereon of at least one crystal having a spinel structure, having a magnetic permeability, in vacuo, ;t,, B/H exceeding 1.2 at temperatures lower than the Curie point, a resistivity at the Curie point exceeding ohm-cm, and a chemical composition having the formula A Cr Z wherein A is one of the members of the group consisting of Cd, Zn, Hg, Mn, Fe", Co, Mg, Ni, Pb,

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Compounds Of Iron (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Soft Magnetic Materials (AREA)
  • Thin Magnetic Films (AREA)
US789506A 1968-01-11 1969-01-07 Transmission element for magneto-optical applications, particularly for the modulation of infrared radiation in the wavelength range between 1 and 20 microns Expired - Lifetime US3580664A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6800387A NL6800387A (enrdf_load_stackoverflow) 1968-01-11 1968-01-11

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US3580664A true US3580664A (en) 1971-05-25

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US (1) US3580664A (enrdf_load_stackoverflow)
FR (1) FR2005197A1 (enrdf_load_stackoverflow)
GB (1) GB1238831A (enrdf_load_stackoverflow)
NL (1) NL6800387A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0255959A1 (en) * 1986-08-08 1988-02-17 Sumitomo Electric Industries Limited Magnet-electro-optic effect light modulator
EP0361236A1 (en) * 1988-09-16 1990-04-04 Casio Computer Company Limited Magnetic apparatus
US6232763B1 (en) * 1993-03-29 2001-05-15 Matsushita Electric Industrial Co., Ltd. Magneto-optical element and optical magnetic field sensor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491026A (en) * 1967-05-19 1970-01-20 Rca Corp Ferromagnetic-semiconductor composition

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491026A (en) * 1967-05-19 1970-01-20 Rca Corp Ferromagnetic-semiconductor composition

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Baltzer et al., Insulating Ferromagnetic Spinels Phys. Rev. Letters Vol. 15, No. 11 (13 Sept. 1965) pp. 493 495 350/151 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0255959A1 (en) * 1986-08-08 1988-02-17 Sumitomo Electric Industries Limited Magnet-electro-optic effect light modulator
US4806885A (en) * 1986-08-08 1989-02-21 Sumitomo Electric Industries, Ltd. Magnet-electro-optic effect light modulator
EP0361236A1 (en) * 1988-09-16 1990-04-04 Casio Computer Company Limited Magnetic apparatus
US4966445A (en) * 1988-09-16 1990-10-30 Casio Computer Co., Ltd. Optical device using magnetic thin films and electric field means
US6232763B1 (en) * 1993-03-29 2001-05-15 Matsushita Electric Industrial Co., Ltd. Magneto-optical element and optical magnetic field sensor

Also Published As

Publication number Publication date
GB1238831A (enrdf_load_stackoverflow) 1971-07-14
DE1816031A1 (de) 1969-07-31
DE1816031B2 (de) 1976-04-08
FR2005197A1 (enrdf_load_stackoverflow) 1969-12-05
NL6800387A (enrdf_load_stackoverflow) 1969-07-15

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