Influence of In Doping on the Refractive Indices of Lithium Niobate

Judd-Ofelt Spectroscopic Study of Er:In:LiNbO3 Crystals For Integrated Optics

“…In case one carries out an unpolarized measurement on a Z ‐cut LiNbO 3 crystal, the X ed and X md are simply given by X ed = X ed ( n o ) and X md = X md ( n o ). In n o and n e are ordinary and extraordinary refractive index, respectively, which can be evaluated according to the SE reported by Kasemir et al 15 Although the Kasemir SE is not sufficiently accurate as demonstrated above, it can be seen from the local field correction factors shown in that an index deviation on the order of 10 −2 cannot significantly affect the J–O results. For the 1530 nm band the measured refractive indices given in Table I were used in the J–O analysis.…”

“…(2) In Doping Level Dependence of Index of Refraction Table I brings together also the measured refractive indices of the studied crystals at the wavelengths of 1536, 633, and 473 nm. For reference purposes, the values calculated using the Sellmeier equation (SE) reported by Kasemir et al 15 for the only In-doped LiNbO 3 crystals are also listed in Table I (the data in the parentheses). As the Kasemir SE is only valid for the wavelength o1.1 mm, the index at the 1536 nm wavelength could not be predicted and is not given in Table I.…”

“…In Eqs. (2) and (3) n o and n e are ordinary and extraordinary refractive index, respectively, which can be evaluated according to the SE reported by Kasemir et al 15 Although the Kasemir SE is not sufficiently accurate as demonstrated above, it can be seen from the local field correction factors shown in Eqs. (2) and (3) that an index deviation on the order of 10 À2 cannot significantly affect the J-O results.…”

“…However, heavy MgO codoping causes difficulty in growing high optical‐quality Er/Mg‐codoped single‐crystal while moderate MgO doping cannot effectively suppress the photorefractive effect. In addition to Mg 2+ , other dopants like Zn 2+ , 11 Sc 3+ , 12 In 3+ , 13–15 Hf 4+ , 16 Zr 4+ , 17,18 and Sn 4+ 19 can also effectively suppress the photorefractive effect, and the optical damage threshold concentration is 7.5, 2.0, 3.0, 4.0, 2.0, and 2.5 mol%, respectively, for a crystal grown from a congruent melt. In comparison with MgO‐, ZnO‐, or HfO 2 ‐doped LiNbO 3 , the indium‐doped crystal needs a lesser amount of dopants to prevent the photorefractive effect, making it possible to improve the optical quality of the crystal when codoped with rare‐earth ion.…”

Emission and absorption cross section spectra of Er3+ in LiNbO3 crystals codoped with indium

“…Although addition of .4.6 mol% MgO into growth melt can effectively suppress the photorefractive effect, 10 heavy MgO codoping causes difficulty in growing high opticalquality Er:Mg:LN single crystal while moderate MgOdoping cannot effectively suppress the photorefractive effect. In addition to the Mg 2+ , the In 3+ dopant can also effectively suppress the photorefractive effect, [11][12][13] and a lesser amount of dopants (.3.0 mol%) is required to prevent the photorefractive effect, making it possible to grow high optical quality Er-In-codoped LN singlecrystal. Therefore, an Er:LN crystal codoped with .1.5 mol% In 2 O 3 would be a promising substrate material for realization of optical-damage-resistant Ti (or Zn vapor)-diffused Er:LN active waveguide device.…”