American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Bell Laboratories

Lucent Technologies Inc.

Bell Telephone Laboratories

George W Berkstresser

Joseph Shmulovich

Charles D Brandle, Jr

Tai-Chan D Huo

Stuart L Blank

Steven J Licht

Vincent Jerome Fratello

Alejandro J Valentino

Robert Ralph Abbott

In an arrangement substantially like an optical isolator, appropriate choice of the composition of the magneto-optic element can result in a variable optical attenuator. The composition is selected to vary in the direction of light propagation, and also is selected such that the magneto-optic element comprises a compensation wall. The compensation wall is movable in response to a change in the temperature of the magneto-optic element, whereby the attenuation of the device is changed.

Article comprising a variable optical attenuator

The invention is a technique for the growth of single crystals of rare earth doped rare-earth orthosilicate crystals which may be used as the laser medium in solid-state non-semiconductor lasers. This type of laser has applications in electronics, communications, aerospace systems, and manufacturing technology where high optical output lasers are utilized. Of particular interest is the Y.sub.2-x Nd.sub.x SiO.sub.5 crystal, with x being up to 0.3, which may be efficiently pumped by a semiconductor laser, solid state non-semiconductor laser, a flashlamp or some other source of light radiation, and has been found to be operable at very high optical output. The rare-earth orthosilicate crystals are grown in accordance with this invention by a Czochralski technique from a molten mixture of constituent oxides in an inert atmosphere containing oxygen. Inclusion of oxygen in the inert atmosphere in concentration of from about 300 to about 9,000 PPM of oxygen resulted in substantial reduction in the density of light scattering defect sites and, thus, in substantial increase in the optical energy which may be applied to the crystal without causing substantial damage to the crystal in comparison to the crystals grown in an inert atmosphere containing less than 300 PPM, such as 200 PPM and less, of oxygen. By application of the growth atmosphere composition control, optical damage thresholds have been increased by more than an order of magnitude.

Method of growing rare earth doped orthosilicates(LN2-XREXSIO5)

Certain yttrium orthosillicate phosphors doped with various rare-earths are particularly suitable for use in various display devices including cathode ray tubes. Included are single crystal phosphors which exhibit high brightness and long life under high energy excitation and conventional powder phosphors with great sensitivity.

Display devices with yttrium orthosilicate phosphors

Light output of single crystal phosphors used on cathode ray tubes can be vastly improved by use of a microfaceted surface structure conveniently produced by use of a single crystal epitaxial layer with lattice constant slightly larger than the single crystal substrate. Such epitaxial layers are conveniently grown using substituents that increase the lattice constant compared to the single crystal substrate.

Cathode ray tube with single crystal target

The luminescent screen of a cathode ray tube includes an array of monocrystalline or amorphous phosphor rod-like elements which are covered with a reflective coating except for one end of each element which serves as an output face. The phenomenon of the light trapping is advantageously exploited to achieve enhanced brightness. The screen is illuminated with an electron beam which has an essentially oblong cross section and which is oriented along the elongated dimension of the elements. In one embodiment the elements comprise epitaxial Lu.sub.3 Al.sub.3 Ga.sub.2 O.sub.12 :Ce on the top of a YAG substrate, and a light absorbing layer of Lu.sub.3 Al.sub.3.5 Fe.sub.1.5 O.sub.12 is formed on the bottom of the substrate. A printer utilizing such a CRT is described. Also described is a configuration in which each of the rod-like elements functions as a laser.

Electron beam pumped laser

A novel epitaxial phosphor having high luminosity at about 540 nm has the composition (Y.sub.3-x-y Tb.sub.x RE.sub.y)(Al.sub.5-w Ga.sub.w)O.sub.12, with RE being one (or more) 4f-type rare earth(s) other than Tb, 0.09&lt;x&lt;0.7, and 1.5&lt;w&lt;2.5. In preferred embodiments, RE is Lu, Yb, or Tm, 0.1&lt;x&lt;0.3, and 1.8&lt;w&lt;2.2. In further preferred embodiments, the phosphor composition is adjusted to yield a material having a lattice constant within 0.002 nm of the lattice constant of the substrate, typically Y.sub.3 Al.sub.5 O.sub.12. The phosphor is typically grown by liquid phase epitaxy and has application in a variety of apparatus, including avionic displays and flight simulators.

Visual display system comprising epitaxial terbium-activated garnet

A phosphor for use in CRTs comprises (Y.sub.3-p-m-n R.sub.p Pr.sub.m Tb.sub.n)(Al.sub.5-q Z.sub.q)O.sub.12, where R is a lanthanide element and Z is a Group III element. One embodiment described is a single crystal of (Y.sub.3-m-n Pr.sub.m Tb.sub.n)Al.sub.5 O.sub.12 in which the trivalent Pr and Tb activators exhibit co-emission and the phosphor emits white light.

Pr:tb activated phosphor for use in CRTS

Electron beam pumped rod-like light emitters

The disclosed display apparatus comprises a novel high intensity broadband-emitting phosphor. The phosphor is single crystal material in which Tb acts as sensitizer of Ce, the activator. The composition of the phosphor is (Y.sub.3-x-y-z Ce.sub.x Tb.sub.y RE.sub.z) Al.sub.5-w X.sub.w O.sub.12, where RE is one or more 4f-type rare earths other than Y, Ce, and Tb, X is Sc, Ga, or In, and 0&lt;x.ltoreq.0.06, 0&lt;y.ltoreq.0.5, 0.ltoreq.z.ltoreq.2, 0.ltoreq.w.ltoreq.3. In preferred embodiments z and w are either zero, or RE is Lu and X is Ga. The phosphor is typically grown epitaxially by LPE on a Y.sub.3 Al.sub.5 O.sub.12 substrate, and has application in a variety of apparatus, including aircraft cockpit head-up displays and flight simulators.

Visual display system utilizing high luminosity single crystal garnet

The manufacture of magnetic bubble devices typically involves a step of epitaxially depositing a layer of a garnet material on a substrate having suitable lattice parameters, e.g., layers of certain rare earth-iron garnets are conveniently deposited on a gallium-gadolinium garnet substrate. Deposition by liquid epitaxy has been preferred and, in particular, deposition from a melt comprising garnet materials in a PbO--B.sub.2 O.sub.3 flux. According to the invention, garnet layers are epitaxially grown from a melt comprising a PbO--V.sub.2 O.sub.5 flux. Growth from such melt has desirably slow kinetics, resulting in slow deposition as is beneficial especially for the growth of layers on an assembly of substrates. Additional benefits are ease of removal of liquid droplets remaining on a grown film upon removal from the melt, both by spinning and by rinsing.

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Bridgewater, NJ, United States of America

George W Berkstresser