Birefringent optical waveguides of aluminum garnet
First Claim
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1. An optical waveguide structure comprising, in combination, a waveguiding body composed of a first crystalline aluminum garnet, and a cladding comprising an epitaxially deposited layer of a second crystalline aluminum garnet, wherein said second crystalline aluminum garnet has a lower refractive index than said first crystalline aluminum garnet, and wherein the lattice dimensions between said first and said second crystalline aluminum garnet are sufficiently different to impose a strain of at least 0.001% on said first crystalline aluminum garnet waveguiding body, thereby causing a stress with resultant birefingence in said first crystalline aluminum garnet waveguiding body
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Abstract
This invention provides birefringent optical waveguide structures of crystalline aluminum garnet of a high refractive index which are clad with crystalline aluminum garnet of a lower refractive index. Due to predetermined lattice mismatch between garnet substrate and cladding layer, strain is induced which causes a stress with resultant birefringence in the waveguide layer. When linearly polarized light enters such stressed waveguide in certain orientations, the linear polarization will be preserved by the stress-induced birefringence. These birefringent clad waveguides can be in the form of slabs, channels, ribs, or any of the typical optical waveguide structures. They are useful at high temperature.
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Citations
21 Claims
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1. An optical waveguide structure comprising, in combination, a waveguiding body composed of a first crystalline aluminum garnet, and a cladding comprising an epitaxially deposited layer of a second crystalline aluminum garnet, wherein said second crystalline aluminum garnet has a lower refractive index than said first crystalline aluminum garnet, and wherein the lattice dimensions between said first and said second crystalline aluminum garnet are sufficiently different to impose a strain of at least 0.001% on said first crystalline aluminum garnet waveguiding body, thereby causing a stress with resultant birefingence in said first crystalline aluminum garnet waveguiding body
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- 3. The optical waveguide of claim 2 wherein the aluminum garnets for the higher refractive index body of the waveguide and for the epitaxial cladding layer are selected from aluminum garnets of the composition
- space="preserve" listing-type="equation">R.sub.3 (Al,T).sub.5 O.sub.12
wherein R represents one or more of the elements selected from the group consisting of calcium, magnesium, yttrium, lanthanum, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium; and T represents one or more of the 3-valent elements selected from the group consisting of gallium, indium, and scandium; with the provisos that (1) the molar ratio of the combined concentration of indum plus scandium to aluminum does not exceed 2 ;
3; and
that(2) if R is one or both of Ca+2 and Mg+2, then T includes one or both of Ge+4 and Si+4 in equimolar concentration relative to the Ca+2 and/or Mg+2 to achieve an average cation charge of three in the crystal.
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4. The optical waveguide of claim 1 wherein the body of the waveguide is an aluminum garnet selected from the composition (Y,Lu)3 (Al,In)5 O12, (Y,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 (Al,In)5 O12, (Tb,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 Al5 O12, Ho3 (Al,In)5 O12, Ho3 (Al,Sc)5 O12 and Ho3 Al5 O12.
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5. The optical waveguide of claim 4 wherein the epitaxial cladding layer is yttrium aluminum garnet.
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6. The optical waveguide of claim 4 wherein the body of the waveguide has the composition Ho3 Al5 O12 and the epitaxial cladding layer is yttrium aluminum garnet.
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7. The optical waveguide of claim 4 wherein the body of the waveguide has the composition Tb1.75 Lu1.25 Al5 O12 and the epitaxial cladding layer is yttrium aluminum garnet.
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8. The optical waveguide of claim 3 comprising an yttrium aluminum garnet base, having epitaxially deposited thereon an aluminum garnet waveguiding body of the composition R3 (Al,T)5 O12 having a higher refractive index than said yttrium aluminum garnet, and having an epitaxial cladding layer of yttrium aluminum garnet on said aluminum garnet of the composition R3 (Al,T)5 O12.
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9. The optical waveguide of claim 8 wherein said aluminum garnet waveguiding body is in the form of a waveguiding rib.
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10. The optical waveguide of claim 9 wherein said waveguiding rib is located within a channel formed in the yttrium aluminum garnet base.
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11. The optical waveguide of claim 3 having a waveguiding body in the form of an elongated waveguiding member, having deposited thereon an epitaxial cladding layer of an aluminum garnet having a lower refractive index than said waveguiding body.
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12. The optical waveguide of claim 11 wherein said elongated waveguiding member is an optical slab.
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13. The optical waveguide of claim 12 wherein the epitaxial cladding layer is yttrium aluminum garnet.
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14. The optical waveguide of claim 13 wherein the optical slab is an aluminum garnet selected from the composition (Y,Lu)3 (Al,In)5 O12, (Y,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 (Al,In)5 O12, (Tb,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 Al5 O12, Ho3 (Al,In)5 O12, Ho3 (Al,Sc)5 O12 and Ho3 Al5 O12.
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15. The method for forming an optical waveguide according to claim 1 which comprises providing a base of a first aluminum garnet, epitaxially depositing thereon a second aluminum garnet having a higher refractive index than said first aluminum garnet, and epitaxially depositing on said second aluminum garnet a third aluminum garnet cladding layer having a lower refractive index than said second aluminum garnet.
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16. The method of claim 15 wherein said first and said third aluminum garnet have the same composition.
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17. The method of claim 16 wherein said first and said third aluminum garnet are both yttrium aluminum garnet.
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18. The method of claim 17 wherein said second aluminum garnet is selected from the composition (Y,Lu)3 (Al,In)5 O12, (Y,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 (Al,In)5 O12, (Tb,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 Al5 O12, Ho3 (Al,In)5 O12, Ho3 (Al,Sc)5 O12 and Ho3 Al5 O12.
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19. The method for making an elongated optical waveguide according to claim 1 which comprises forming an elongated waveguiding body of a first aluminum garnet, and epitaxially depositing thereon a second aluminum garnet having a lower refractive index than said first aluminum garnet.
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20. The method of claim 19 wherein said elongated waveguiding body is an optical slab, and said second aluminum garnet is yttrium aluminum garnet.
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21. The method of claim 20 wherein said optical fiber is an aluminum garnet having a composition selected from the group consisting of (Y,Lu)3 (Al,In)5 O12, (Y,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 (Al,In)5 O12, (Tb,Lu)3 (Al,Sc)5 O12, (Tb,Lu)3 Al5 O12, Ho3 (Al,In)5 O12, Ho3 (Al,Sc)5 O12 and Ho3 Al5 O12.
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Current AssigneeAlliedsignal Inc. (Honeywell International Inc.)
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Original AssigneeAlliedsignal Inc. (Honeywell International Inc.)
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Inventorsvan de Vaart, Herman, Gualtieri, Devlin M., Hou, Janpu, Morris, Robert C.
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Primary Examiner(s)ULLAH, AKM E
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Application NumberUS07/797,009Time in Patent Office400 DaysField of Search385/130-141US Class Current385/130CPC Class CodesG02B 6/02 Optical fibres with claddin...G02B 6/122 Basic optical elements, e.g...G02B 6/131 by using epitaxial growth e...
