US 5,393,561 AGranted

Segmented waveguides having selected bragg reflection characteristics

AssigneeE. I. Du Pont de Nemours and Company

InventorsJohn D. Bierlein, William Bindloss, Fredrik Laurell, Jerald D. Lee

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Abstract

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.

Claims20

Dependent claims

A process for preparing a channel waveguide for a wavelength conversion system wherein (1) the z-cut surface of a z-cut substrate of single crystal material having the formula K.sub.1-x Rb.sub.x TiOMO.sub.4 wherein x is from 0 to 1 and M is P or As is provided with an optically smooth surface, (2) a molten salt containing cations is provided in an amount effective to provide upon exposure to said optically smooth surface sufficient cation replacement to change the index of refraction with respect to the index of refraction of said substrate, (3) a masking material is applied on said substrate to provide a pattern of aligned areas along a portion of said optically smooth surface which are alternately masked with a material resistant to said molten salt and unmasked, (4) said masked substrate is immersed in said molten salt, thereby providing cation replacement in said unmasked areas;

and (5) the masking material is removed from said substrate, characterized by:
said molten salt containing cations selected from the group consisting of Rb.sup.+, Cs.sup.+ and Tl.sup.+, with the proviso that when the channel waveguide is prepared for a wavelength conversion system which uses quasi-phase matching, (a) the molten salt also contains cations selected from the group consisting of Ba.sup.++, Sr.sup.++ and Ca.sup.++ and when x is greater than 0.8, cations selected from Tl.sup.+ and Cs.sup.+, and (b) the molten salt contains said cations in an amount effective to provide upon said exposure to said unmasked areas of the optically smooth surface, a nonlinear optical coefficient which is changed with respect to the nonliner optical coefficient of the substrate;
and
the lengths of said masked and unmasked areas being sized such that after said cation replacement in the unmasked areas, a channel waveguide is provided at said portion of the optically smooth surface which comprises a series of aligned sections of optical materials having a periodic structure suitable to provide wavelength conversion for incident waves at an incident wavelength and a Bragg reflection for said incident wavelength which has a wavelength essentially equal to the wavelength of said incident waves.

1 more element

and (5) the masking material is removed from said substrate, characterized by:
said molten salt containing Ba.sup.++ and cations selected from the group consisting of Rb.sup.+ and Tl.sup.+, with the proviso that when the channel waveguide is prepared for a wavelength conversion system which uses quasi-phase matching, (a) the molten salt contains Tl.sup.+ when x is greater than 0.8, and (b) the molten salt contains said cations in an amount effective to provide upon said exposure to said unmasked areas of the optically smooth surface, a nonlinear optical coefficient which is changed with respect to the nonliner optical coefficient of the substrate;
and
the lengths of said masked and unmasked areas being sized such that after said cation replacement in the unmasked areas, a channel waveguide is provided at said portion of the optically smooth surface which comprises a series of aligned sections of optical materials having a periodic structure suitable to provide wavelength conversion for incident waves at an incident wavelength and a Bragg reflection for said incident wavelength which has a wavelength essentially equal to the wavelength of said incident waves.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 08/036,376Filed 24 Mar 1993 · division
Priority: 19 Sep 1991
Granted: 28 Feb 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G02F 1/3775
In an optical waveguide structure: with a periodic structure, e.g. domain inversion, for quasi-phase-matching [QPM]
G02F 1/3548
Particular phase matching techniques: quasi phase matching [QPM], e.g. using a periodic domain inverted structure
G02F 1/3553
Crystals: having the formula MTiOYO4, where M=K, Rb, TI, NH4 or Cs and Y=P or As, e.g. KTP
G02F 2201/307
Grating: reflective grating, i.e. Bragg grating