Refractive index dispersion and anisotropy in NaGd(WO4)2 single crystal

✍ Scribed by S. Perets; M. Tseitlin; R.Z. Shneck; Z. Burshtein

• Book ID: 104075353
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 176 KB
• Volume: 30
• Category: Article
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2007.06.004

✦ Synopsis

Refractive index characteristics were measured in the tetragonal, scheelite-like, NaGd(WO 4 ) 2 (NGW) single crystal. The room temperature ordinary refractive-index dispersion was measured by the minimum-deviation method between 320 and 1342 nm. The refractiveindex anisotropy was measured between 400 and 1860 nm using a combination of bireflection in an oriented single crystal prism, and birefringence modulation in an oriented plane-parallel plate. The crystal is positive uniaxial, with its optic axis parallel to the crystallographic c-axis. The dispersion was fitted to a simple two-parameter Sellemeier function. The anisotropy dispersion was also fitted to an empiric function. Taking the 632.8 nm wavelength (the He-Ne laser line) as a representative of the visible range, the ordinary refractive index is n o = 1.989(1), and the anisotropy (n e À n o ) = 0.00342(1). The refractive indices' changes with temperature were measured between room temperature and $200 °C at k = 632.8 nm, yielding dn o /dT = À 10.70 • 10 À5 °CÀ1 and dn e /dT = À 4.17 • 10 À5 °CÀ1 .