E.i. Dupont De Nemours and Company

E. I. Du Pont De Nemours

John D Bierlein

August Ferretti

Mark Gerrit Roelofs

Jerald D Lee

Lothar H Brixner

Thurman E Gier

William Bindloss, Jr

Fredrik Laurell

William Yang-Hsing Hsu

Lap-Tak Andrew Cheng

Daniel B Laubacher

Lap K Cheng

Carolus J Van Der Poel

Patricia A Morris

Albert A Ballman

Joseph B Brown, Iii

Segmented waveguides for wavelength conversion (e.g., waveguides comprising alternating sections of crystalline substrate having the formula K.sub.1-x Rb.sub.x TiOMO.sub.4 where x is from 0 to 1 and M is P or As and sections of substrate material in which cations of said substrate have been partially replaced) and devices and processes employing segmented waveguides for wavelength conversion are disclosed wherein a periodic structure along the waveguide provides a Bragg reflection having a wavelength essentially equal to the wavelength of the input wave used for wavelength conversion. Also disclosed is a process for preparing a channel waveguide for a wavelength conversion system wherein areas along a portion of a crystal substrate surface used for forming the desired channel are alternately masked and unmasked during cation replacement by immersion in a molten salt.

Segmented waveguides having selected bragg reflection characteristics

Method and device for wavelength conversion using type II phase matching are characterized by employing a crystal consisting essentially of doped MTiOXO.sub.4 (wherein M is K, Rb and/or Tl and X is P and/or As) containing Fe, Nb and/or Ta dopant in an amount, totalling at least about 100 ppm, effective to increase the n.sub.z -n.sub.x optical birefringence of the doped crystal at least about 0.001 compared to a crystal without the dopant. Generation of output waves of an optical birefringence higher than the highest corresponding optical birefringence of a crystal without the dopant is disclosed. Among the useful crystals are crystals consisting essentially of doped MTiOXO.sub.4 containing at least about 100 ppm Ta.

Increasing the birefringence of KTP and its isomorphs for type II phase

There is disclosed an optical waveguide comprising a K.sub.1-x Rb.sub.x TiOmO.sub.4 single crystal substrate, wherein x is from 0 to 1 and M is P or As, having at least one optically smooth surface wherein sufficient K.sup.+ and/or Rb.sup.+ have been replaced by ions selected from at least one of H.sup.+ and NH.sub.4.sup.+ and, optionally, at least one monovalent ion selected from Rb.sup.+, Cs.sup.+, Tl.sup.+, and/or at least one divalent ion selected from Ba.sup.+2, Sr.sup.+2, Ca.sup.+2 and Pb.sup.+2 to chance the surface index of refraction at least a 0.00025 with respect to the index of refraction of the single crystal substrate. One process disclosed for producing an optical waveguide comprises the steps of contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOmO.sub.4 with an ion exchange medium capable of supplying said replacement ions, at a temperature of from about 100.degree. C. to about 600.degree. C. for a time sufficient to increase the surface index of refraction at least about 0.00025 with respect to the index of refraction of the single crystal by replacing K.sup.+ and/or Rb.sup.+ of said single crystal with said ions supplied by the exchange medium, and cooling the resulting crystal. Another process disclosed for producing an optical waveguide comprises the step of applying a DC voltage of from about 20 V per cm of crystal thickness to about 2000 V per cm of crystal thickness across the z-surfaces of a z-cut K.sub.1-x Rb.sub.x TiOmO.sub.4 single crystal, in the presence of a proton source at a temperature of from about -40.degree. C. to 400.degree. C. for a time sufficient to raise the index of refraction underneath the anode by at least 0.00025 with respect to the index of refraction of the single crystal by replacing K.sup.+ and/or Rb.sup.+ of said single crystal with H.sup.+. A nonlinear optic device using the optical waveguide of the invention is also disclosed.

Processes for preparation of ion exchanged crystalline waveguides

Segmented waveguides having selected Bragg reflection characteristics

Articles and process for wavelength conversion are disclosed which use a series of aligned sections of optical materials for wavelength conversion selected from materials having the formula K.sub.1-x Rb.sub.x TiOMO.sub.4 where x is from 0 to 1 and M is selected from P and As and materials of said formula wherein the cations of said formula have been partially replaced by at least one of Rb.sup.+, Tl.sup.+ and Cs.sup.+, and at least one of Ba.sup.++, Sr.sup.++ and Ca.sup.++. The series of sections is characterized with regard to a change in nonlinear optical coefficient, section length, and section .DELTA.k (i.e., the difference between the sum of the propagation constants for the incident waves and the sum of the propagation constants for the waves generated). The sections are selected such that the sum for the series of the product of the length of each section with the .DELTA.k is equal to about 2.pi.N (where N is an integer other than zero) and the nonlinear optical coefficient for at least one section is changed relative to the nonlinear optical coefficient for at least one adjacent section. Also disclosed is a process for preparing a channel waveguide for wavelength conversion systems wherein areas along a portion of a crystal substrate surface used for forming the desired channel are alternately masked and unmasked during cation replacement by immersion in a molten salt.

Wavelength conversion by quasi phase matching and the manufacture and

There is disclosed an optical waveguide comprising a K.sub.1-x Rb.sub.x TiOMO.sub.4 single crystal substrate, wherein x is from 0 to 1 and M is P or As, having at least one optically smooth surface wherein sufficient K.sup.+ and/or Rb.sup.+ have been replaced by ions selected from at least one of H.sup.+ and NH.sub.4.sup.+ and, optionally, at least one monovalent ion selected from Rb.sup.+, Cs.sup.+, Tl.sup.+, and/or at least one divalent ion selected from Ba.sup.+2, Sr.sup.+2, Ca.sup.+2 and Pb.sup.+2 change the surface index of refraction at least about 0.00025 with respect to the index of refraction of the single crystal substrate. One process disclosed for producing an optical waveguide comprises the steps of contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOMO.sub.4 with an ion exchange medium capable of supplying said replacement ions for sufficient time at a temperature of from about 100.degree. C. to about 600.degree. C., and cooling the resulting crystal. Another process disclosed for producing an optical waveguide comprises the step of applying a DC voltage of from about 20 V per cm of crystal thickness to about 2000 V per cam of crystal thickness across the z-surfaces of a z-cut K.sub.1-x Rb.sub.x TiOMO.sub.4 single crystal, in the presence of a proton source for sufficient time at a temperature of from about -40.degree. C. to 400.degree. C. A nonlinear optic device using the optical waveguide of the invention is also disclosed.

Ion exchanged crystalline waveguides and processes for their preparation

A composition is disclosed which consists essentially of doped crystalline MTiOXO.sub.4 (wherein M is selected from the group consisting of K, Rb and Tl, X is selected from the group consisting of P and As) which contain at least about 100 ppm total of at least one dopant selected from the group consisting of Ga, Al and Si. The compositions generally have low ionic conductivity, and may be prepared using an improved flux process wherein Ga, Al and/or Si dopant is added to the flux in a total amount of at least about 0.5 mole % and the crystallization temperature is controlled to provide a crystalline composition containing the desired amount of dopant.

Doped crystalline compositions and a method for preparation thereof

Articles and process for wavelength conversion are disclosed which use a series of aligned sections of optical materials which are suitably balanced over the series with regard to the section length and the section .DELTA.k (i.e. the difference between the sum of the propagation constants for the incident waves and the sum of the propagation constants for the waves generated). The sections are selected such that the sum for the series of the product of the length of each section with the .DELTA.k is equal to about zero, and the length of each section is less than its coherence length. Embodiments are disclosed wherein at least one of the optical materials is optically nonlinear and/or wherein a layer of nonlinear optical material is provided adjacent to the series of sections. Also disclosed is a process for preparing a channel waveguide for wavelength conversion systems wherein areas along a portion of a crystal substrate surface used for forming the desired channel are alternately masked and unmasked during cation replacement by immersion in a molten salt.

Optical articles for wavelength conversion and their manufacture and use

There is disclosed a process for producing an optical waveguide comprising contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOMO.sub.4 wherein x is from 0 to 1 and M is P or As with a specified molten salt of at least one of Rb, Cs and Tl at a temperature of from about 200.degree. C. to about 600.degree. C. for a time sufficient to increase the surface index of refraction at least about 0.00025 with respect to the index of refraction of the starting crystal, and cooling the resulting crystal. The product made thereby and a waveguide device using the same are also disclosed.

Process for producing an optical waveguide

Process for producing an optical waveguide and the product therefrom

Crystals of compounds of the type (K, Rb, Tl, NH.sub.4)TiO(P, As)O.sub.4 with the proviso that when NH.sub.4 is present, As is absent, can be grown by hydrothermal methods. The crystals are optically biaxially positive, and piezoelectric and are useful in parametric amplifiers, oscillators, second harmonic generators, modulators and the like.

Growing community of inventors

Wilmington, DE, United States of America

John D Bierlein