Optical nonlinearity material and production method therefor

Glass manufacturing – Processes – Devitrifying glass or vitrifying crystalline glass

Reexamination Certificate

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C065S033100

Reexamination Certificate

active

06581414

ABSTRACT:

TECHNICAL FIELD
The present invention relates to optical non-linear material made of glass, and in particular to optical non-linear material containing micro crystal particles and a method for manufacturing the same.
BACKGROUND ART
Conventionally, information transmission using light, such as with the use of optical fibers, has found increasingly wider use for large-volume information transmission. Such information transmission systems require various optical functional elements. To manufacture such optical functional elements, materials having second-order optical non-linearity are important. As materials having second-order optical non-linearity, crystalline materials such as LiNbO
3
are widely utilized. Meanwhile, it is desirable to use glass material in terms of a stable connection with an optical fiber, low loss of the transmitted light, low cost, and a wide rage of transmitting wavelength.
For example, Japanese Patent Laid-open Application No. Hei 10-111526 proposes that UV-excited poling is applied to Ge-doped SiO
2
-based glass to impart thereto a second-order optical non-linearity in which a d-constant, or an optical non-linearity constant, is 2.5 pm/V or larger.
As such, it has conventionally been proposed that UV-excited poling is applied to glass materials to impart remarkably large second-order optical non-linearity thereto. However, there has still been a desire to manufacture glass materials having larger second-order optical non-linearity more easily.
The present invention has been conceived in view of the above, and aims to provide a material having improved optical non-linearity and a manufacturing method therefor.
DISCLOSURE OF INVENTION
Non-linear material according to the present invention is characterized by the fact that micro-crystal particles, obtained by partially crystallizing a glass phase, are dispersed in the glass phase. Presence of micro-crystal particles enables development of large second-order optical non-linearity.
Preferably, the micro-crystal particles each have a diameter of 10 to 20 &mgr;m.
Preferably, glass materials are subjected to UV-excited poling, in which UV strength is 10 mJ/cm
2
or more and an electric field strength is 3×10
4
V/cm or more, so that a non-linear optical constant, or a d-constant, becomes 1 pm/v or more.
A method for manufacturing an optical non-linear material according to the present invention is characterized by the fact that glass material is subjected to partial crystallization. Generation of micro-crystal particles as above enables development of large second-order optical non-linearity in the glass material.
Preferably, glass materials are subjected to UV-excited poling, in which UV strength is 10 mJ/cm
2
or more and an electric field strength is 3×10
4
V/cm or more, so that a non-linearity optical constant, a d-constant, becomes 1 pm/V or more.
A method for manufacturing non-linear material according to the present invention is characterized by the fact that glass material is subjected to partial crystallization to disperse micro-crystal particles, or partially crystallized glass phase, and then to UV optical poling. That is, when glass material is subjected to partial crystallization in advance, second-order optical non-linearity can be developed in the glass material through UV-excited poling using a relatively low electric field.
Preferably, the partial crystallization is UV-excited poling in which UV strength is 10 mJ/cm
2
or more and an electric field strength is 3×10
4
V/cm or more, and UV-excited poling at a subsequent step is applied using a lower voltage than that which is used in the UV-excited poling for partial crystallization.


REFERENCES:
patent: 6246815 (2001-06-01), Fujiwara et al.
patent: 6374026 (2002-04-01), Fujiwara et al.
patent: 5-119362 (1993-05-01), None
patent: 8-146475 (1996-06-01), None
patent: 8328061 (1996-12-01), None
patent: 9090447 (1997-04-01), None
patent: 9-166798 (1997-06-01), None
patent: 10-161164 (1998-06-01), None
patent: WO 96/16344 (1996-05-01), None
Optical Fiber Communication '95 Technical Digest vol. 8 PostconferenceEdition, (Mar. 1995), T. Fujiwara et al., “UV-excited poling and electrically tunable bragg gratings in a germanosilicate fiber” pp. 347-350.
Appl. Phys. Lett., vol. 71, No.8 (Aug. 1997), M. Takahashi et al, “Defect formation in Ge02—Si02glass by poling with ArF excitation”, pp. 993-995.
Appl. Phys. Lett., vol. 71, No. 8 (Aug. 1997), T. Fujiwara et al, “Second-harmonic generation in germanosilicate glass poled with ArF laser irradiation”, pp. 1032-1034.
Appl. Phys. Lett., vol. 70, No. 2 (Jan. 1997), V. Pruneri et al, “Frequency doubling in galliumlanthanum-sulphid optical glass with microcrystals”, pp. 155-157.
Proceedings of SPIE, vol. 3542 (Nov. 1998), Doped Fiber Devices II, t. Fujiwara et al, Second-order nonlinearity and structural change in UV-poled glass, pp. 94-101.
Appll. Phys. Lett., vol. 65, No. 13 (Sep. 1994), H. Hosono et al, “Novel approach for synthesizing Ge fine particles embedded in glass by ion implantation: Formation of Ge manocrystal in SI02—Ge02glasses by proton implantation”, pp. 1632-1634.
Proceedings of Japan Ceramics Society; 11th. Autumn Symposium (Oct.1, 1998 published), A. Narazaki et al, “Nonlinear optical characteristics of the surface-crystallized glass”, p. 241.
Fujiwara et al., “Second-Order Nonlinearity and Structural Change in UV-Pooled Glass,” Proceedings of SPIE, Doped Fiber Devices II, Nov. 1998, vol. 3542, pp. 94-101.

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