TEMPERATURE DEPENDENCE OF FARADAY ROTATION FOR Bi-SUBSTITUTED Tb IRON GARNET FILMS

Abstract

Temperature dependence of Faraday rotation, which causes degradation of isolation at high or low temperature for an optical isolator, was rreasured at 1. 3,um and 0.78,um wavelength together with saturation magnetization and optical transparency for epitaxially grown (TbBi)3FeS012 and ('!bLaBi) 3FeS012 films. Tenperature dependence of faraday rotation for these films w=re smaller than those for (GdBi)3(FeAlGa)S012 films and (GdBi)3FeS012 bulk single crystals.Particularly, thick '!b2.2LaO.2BiO 6FeS012 films show=d less than O.S% sift in Faraday rotation in the temperature range from 0 to ~OoC. Additionally '!b 2 2LaO.2BiO 6FeS012 films had a small saturation magnetization, carpared with Y3FeS012 and sufficient optical transparency in 1.3 ~ 1.S ,urn wavelength for an optical isolator. INI'RODUCTIONBi-substituted rare-earth iron garnets, (RBi)3FeS012' with large Faraday rotation grown by liquid-phase epitaxial (LPE) and flux rrethods have been utilized to replace the conventional YIG (Y3FeS012) single crystals for an optical isolator used in near infrared region. (1),[21 Especially the LPE grown thick films, e.g. (GdBi)3(FeAlGa)S012, excel in productivitity and have realized supply of materials for an optical isolator at low prices. [3] How=ver the temperature dependence of Faraday rotation 9 F of Bi-substituted iron garnet utilizing Gd as a host rare-earth is larger than that of YIG and caused a problem of isolation degradation at higher or low=r temperature when applied to an optical isolator.By employing (DyBi)3FeS012 the temperature dependence of 9 F was improved up to the level of YIG. How=ver r since (DyBi) 1FeS012 has optical absorption peaks around 1. 3 ,urn wavelength, this material is practical for optical isolator used in the 1. S f.i.m band but not in the 1.3 f.i.m band.(4] Although double-layered LPE garnet films or combination of two LPE films with different temperature dependence of 9 F w=re proposed to obtain a flat temperature dependence of 8 F for Bi-sbstituted iron garnet. a single layer LPE film with flat temperature dependence of 8 F has not yet been reported.[SJ, [6] Here w= report the temperature dependence of 9 F for (TbBi)3FeS012' that is a solid solution of hypothetical BiIG and '!bIG which has no optical absorption peaks by rare-earth in the wavelength range from O. B to 1. S f.i.m , and for (TbLaBi) 3FeS012' that is prepared by La OOping to the above solid solution. we will show that (TbBi)3FeS012 and ('!bLaBi)3FeS012 films are exllent in temperature charactaristics for an optical isolator at both 1.3 f.i.m and 0.8 f.i.m wavelength regions.(7), [8] In addition w= report the results of rreasurerrents of their saturation magnetization and optical transparency which are important characteristics for an optical isolator. LPE GRCWI'HTb3-XBiXFes012 (X ~ 0.68-vl.18), Tb2.2LaO.2BiO.6FeS012 and TbIG (Tb 3 Fe S o 12 )films w=re grown by iso-thermal horizontal dipping rrethod on non-magnetic garnet substrates, as snown in Table 1. In order to get further impro~errent of temperature dlipend...

Temperature Dependence Free Magneto-Optical (Tb,Bi)Fe Garnet Films Grown By LPE Method

“…In experimental, several authors reported the TDF Faraday rotator (FR) made by (Tb,Bi)3Fe5O12 for practical applications [1][2][3][4][5]. In experimental, several authors reported the TDF Faraday rotator (FR) made by (Tb,Bi)3Fe5O12 for practical applications [1][2][3][4][5].…”

“…They indicated that a relatively low Bi content suppressed the FR and required a critical thick LPE-grown film over 1500 m for optical isolator applications wavelength at 1550nm for example, which induced the degradation of the crystal uniformity and the optical transparency [1]. They indicated that a relatively low Bi content suppressed the FR and required a critical thick LPE-grown film over 1500 m for optical isolator applications wavelength at 1550nm for example, which induced the degradation of the crystal uniformity and the optical transparency [1].…”

High Figure of Merit Magneto‐Optical Ce‐ and Bi‐Substituted Terbium Iron Garnet Films Integrated on Si

“…TbIG has a Faraday rotation in 1100-1550 nm wavelength range of ≈ +270 to +1000° cm −1 . [23][24][25] Bi-substituted TbIG has been grown by liquidphase epitaxy and flux methods [23][24][25][26][27] or sol-gel methods, [28] and more recently thin films of Ce-and Bi-substituted TbIG (CeTbIG, BiTbIG) were grown on Si by sputtering. [29][30][31][32][33][34] Sputtered BiTbIG with Bi substitution of 14% of the Tb sites has a Faraday rotation of ≈−500° cm −1 at 1550 nm, [29] the same sign as that of CeYIG, which at 1550 nm wavelength had a Faraday rotation of at least −3700° cm −1 .…”