Hashimoto, Tadanori

Kozuka, Hiromitsu

Yoko, Toshinobu

Kyoto University Research Information Repository

TitleInorganic Photonic Materials - Preparation and Third OrderNon-Linear Optical Properties (SOLID STATE CHEMISTRY- Amorphous Materials)Author(s)Yoko, Toshinobu; Kozuka, Hiromitsu; Hashimoto, TadanoriCitationICR annual report (1995), 1: 22-23Issue Date1995-03URL http://hdl.handle.net/2433/65670RightType ArticleTextversionpublisherKyoto University22 /CR Annual Report, Vol. /, /994Inorganic Photonic Materials - Preparation and ThirdOrder Non-Linear Optical PropertiesToshinobu Yoko, Hiromitsu Kozuka and Tadanori HashimotoThird order nonlinear optical properties of various non-conventional glasses such as TeOz-, GaZ03-, Sbz0 3-basedglasses have been examined in relation to glass structure which was studied by using a number of experimentaltechniques (X-ray, neutron diffraction, MAS-NMR, IR, Raman Spectroscopy etc.). In addition, coating filmsof transition metal oxides and metal oxides containing metal fine particles have been prepared by the sol-gelmethod and subjected to various optical characterizations by focusing especially on the third order nonlinearoptical susceptibility, X(3). It is found that a-FeZ03 exhibits the highest i 3 ) value of 5.8xlO- ll esu among theinorganic materials studied so far.Keywords: Inorganic photonic materials! Glasses! Thin films! Sol-gel method! Glass Structure!Third order nonlinear optical susceptibility X(3)The advent of optical glass fibers has made high-speedand long-distance telecommunication possible, leading tothe present highly sophisticated modern media. Thepresent optical telecommunication system is, however,limited by the processing speed of electronics currentlyused. Nonlinear optical (NLO) devices will overcomethis problem because they can switch and process signal ina time scale of 10- 15 s inaccessible to electronics (10- 12 s)without converting it into electronic form. Moreover, itis anticipated that the ultrahigh-speed "opticalcomputer," in which optical switching devices areutilized, will replace the conventional, semiconductor-driven computer in the near future. Therefore, it isurgently necessary to develop nonlinear optical materialswhich can be used as NLO devices. In our laboratory,two types of inorganic NLO materials are studied: (1)non-conventional glasses by melting method, (2) coatingfilms formed on a glass substrate by the sol-gel method.We will present several representative results currentlyobtained in the following.A thin plate of Te02 glass of 5.0X4.0XO.25mm3 insize, which was large enough for various opticalmeasurements, was obtained by a rapid quenchingmethod. The linear refractive index was measured as afunction of wavelength from 486.1 to 1000 nm. Therefractive index at 486.1 nm was as high as 2.239. Theoptical energy band gap was estimated as 3.37 eV fromthe optical absorption spectrum. The third-ordernonlinear optical susceptibility, X(3), was determined bythe third-harmonic generation (THG) method. The X(3)value was as high as lAX 10- 12 esu, about 50 times aslarge as that of Si02 glass. The results are discussedbased on Lines' model in which an influence of cationicempty d-orbital on the nonlinear properties is taken intoSOLID STATE CHEMISTRY -Amorphous Materials-InstructorHASHIMOTO, Tadanori(D Eng)Associate ProfessorKOZUKA, Hiromitsu(D Eng)ProfessorYOKO, Toshinobu(D Eng)Scope of researchTwo main subjects have been studied in this laboratory. The first is to develop a new family of glasses which do notcontain so-called glass formers such as Si02> P20S, B20 3 and so on. Relationships between glass formation andstructure, and then relationships between structure and properties, especially nonlinear optical properties, are tried tobe established. The second is to synthesize new functional inorganic thin films by the sol-gel method which is knownas one of the most advantageous low temperature synthesis processes. Our attention is focused especially on thenonlinear optical properties of these films. Guest ResearchAssociates:INNOCENZI, PlinioJIN, lisunKIM, Sae-HoonKITAOKA, KenjiZHAO, GaolingStudents:FUJIHARA, Shinobu (DC)TERASHIMA, Kentaro (DC)ISHIBASHI, Keiji (MC)OKUNO, Masahiro (MC)UTSUMI, Shigeru (MC)SAKAI, Hideo (MC)SAKIDA, Shinichi (MC)YAMADA, Tetsuya (MC)HATTORI, Takeshi (UG)NAKATA, Kunihiko (UG)account.Rutile and anatase thin films have been prepared bysol-gel method using Ti(OC3H7i)4. Third-order non-linear optical properties of both Ti02 thin films have beeninvestigated by the third-harmonic generation (THG)method and the effect of the polymorph of Ti02 on thethird-order nonlinear optical susceptibility, X(3), has beenexamined. The measured i 3) values of rutile andanatase thin films were 1.4X10- 12 and 9.7X10- 13 esu,respectively. The i 3) values corrected for the porosityof the film were 4.0XlO- 12 (rutile) and 2.4X10- 12 esu(anatase), which are about 100 times as high as that ofSi02 glass used as standard sample (2.8X 10- 14 esu).The measured and corrected i 3) values were discussed incomparison with those calculated on the basis of severalmodels.The third-order nonlinear optical properties of sol-gelderived transition metal oxide, V20 S , Nb20 s and Ta20s,thin films have been investigated by the third-harmonicgeneration method and the effect of the metal-oxygenbond length on the third-order nonlinear opticalsusceptibility, X(3), has been examined. The i 3 )values of V20 S , Nb20 s and Ta20s thin films were1.1X10- 11 , 1.3XlO- 12 and 6.1X10- 13 esu, respectively,which corresponds to an increase of the average bondlength, h, in the order of v-o (h=0.183 nm), Nb-O(h=0.200nm) and Ta-O (h=0.204nm). The presentand previous results indicate that X(3) of these transitionmetal oxides with the empty d orbitals is dominatedmainly by the metal-oxygen bond length rather than thevalence of metal cation. It is predicted on the basis ofLines' model that transition metal oxides with the shortesth exhibit the highest i 3) while non-transition metaloxides with the longest h do the highest i 3).The third-order nonlinear optical properties of sol-gela-Fe203, y-Fe203 and Fe304 thin films have beeninvestigated by the third-harmonic generation (THG)method. Especially, the effects of the valence andcoordination number of Fe ions on the third-ordernonlinear optical susceptibility, i 3 ), have beenexamined. The i 3) values of a-Fe203, y-Fe203 andFe304 thin films were 5.8XlO- 11 , 2.1XlO- 11 and4.0 X10- 10 esu, respectively, which are the highest valuesamong inorganic oxides reported so far. It wasconsidered that X(3) of a-Fe203 and y-Fe203 wasenhanced by the pair excitation process involving thesimulation of magnetically coupled two neighboringFe3+ ions while i 3) of Fe304 by both one- and three-photon resonances. The higher second-hyperpolari-zability, y (Fex/yO) , was obtained when the valence of Feions is 3+ rather than 2+ and octahedrally rather thantetrahedrally coordinated by oxygens.Third-order nonlinear optical properties of sol-gelderived FeTi03 thin films have been investigated by the23third-harmonic generation (THG) method, and the effectof valence of Fe ions on the third-order nonlinear opticalsusceptibility, i 3) , has been examined. The i 3 ) value ofFeTi03 thin film was 3.3 X 10- 12 esu, which is comparableto those or Ti02 polymorphs (rutile and anatase) but oneorder of magnitude lower than of a-Fe203. Second-hyperpolarizability per Fe2+0 formula unit, y (Fe2+0),was one fourth to one third of y (Fe2133+0) and aboutfour times as large as y (Til/24+ 0), indicating that the X(3)value of FeTi03 may be dominated by the y (Fe2+0)rather than y (Til/24+ 0).The preparation process of single phase Pb(Fel/2Nbl/2)03 (PFN) perovskite films on glass substratesby sol-gel method has been investigated and severaloptical properties of the resultant transparent PFN filmshave been examined. The refractive index at 633 nm ofPFN perovskite films is as large as 2.409, which is largerthan Pb3Nb40 13 pyrochlore films by 0.14-0.16 at anywavelength. The i 3) of PFN films is estimated as7.5 X 10- 12 esu, which is the second highest value amongoxides so far obtained. The X(3) of pyrochlore films isestimated as 2.8 X 10- 12 esu, which is one-third as smallas that of PFN films.Silica coating films of 0.5-0.7 mm thickness doped bygold metal particles were prepared by heating gel coatingfilms obtained from solutions of acid-catalyzedmethyltriethoxysilane (MTES) and tetraethoxysilane(TEOS) mixture containing chlorauric acid tetrahydrate.Transparent coating films with deep blue, red, and purplecolors were obtained. Changes in size and shape of thegold particles with the MTES content were observed.Lower MTES contents gave bigger and non-sphericalparticles, while higher MTES contents produced smallerand more spherical particles with a more uniforw sizedistribution. The effect of heat-treatment temperatureon the shape, size, and size distribution of the metallicgold particles was also studied.References1. Yoko T, Hashimoto T and Ishibashi K, NEW GLASS,9, 16-22 (1994) [in Japanese].2. Hashimoto T, Yoko T and Sakka S, Bull. Inst. Chern.Res., Kyoto Univ., 71, 420-429 (1994).3. Hashimoto T, Yoko T and Sakka S, Bull. Chern. Soc.lpn., 67, 653-660 (1994).4. Kim S H, Yoko T and Sakka S, 1. Am. Cerarn. Soc.,76, 2486-90 (1993).5. Hashimoto T, Yoko T and Sakka S, l. Cerarn. Soc.lpn., 101, 52-56 (1993).6. Hashimoto T and Yoko T, Applied Optics, in press.7. Hashimoto T, Yamada T and Yoko T, submitted toPhys. Rev. B.8. Innocenzi P, Kozuka Hand Sakka S, 1. Sol-Gel Sci.Techn., 1, 305-318 (1994).

Inorganic Photonic Materials - Preparation and Third Order Non-Linear Optical Properties (SOLID STATE CHEMISTRY - Amorphous Materials)

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Inorganic Photonic Materials - Preparation and Third Order Non-Linear Optical Properties (SOLID STATE CHEMISTRY - Amorphous Materials)

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