Linear and nonlinear optical characteristics of PbMoO₄ single crystal for optoelectronic applications

Abstract

In the present paper, we studied linear and nonlinear optical properties of lead molybdate (PbMoO4) single crystals grown by Czochralski method. Raman measurement was performed in the range of 50-1000 cm(-1) and 11 active vibration modes were defined in the spectrum. The nature of the observed modes was discussed in detail. Optical absorption of the material was investigated utilizing room temperature transmission and reflection experiments in the spectral range of 360-1000 nm. Spectral changes of absorption coefficient, skin depth, refractive index, optical conductivity, and complex dielectric function of PbMoO4 crystals were studied. Absorption coefficient and optical conductivity exhibited strong increment around 3.0 eV with increasing photon energy. Cut-off wavelength was determined to be 390 nm from the skin depth spectrum. Tauc and derivative spectral analyses revealed the presence of direct bandgap with the energy of 3.05 eV. The static refractive index and dielectric constant were estimated as 2.25 and 5.08, respectively, using Wemple-DiDomenico single oscillator model. Urbach energy was calculated to be 0.071 eV from the exponential dependence of absorption coefficient to photon energy. Dielectric constant increased to 5.42 with energy up to 2.60 eV and then it exhibited decreasing behavior. Second energy derivative analysis of imaginary dielectric function resulted in existence of a critical point at 3.19 eV. First- and third-order nonlinear susceptibilities and nonlinear refractive index were found to be 0.32, 1.9 x 10(-12) and 31.7 x 10(-12) esu, respectively. These results show that the material may be used in UV filter and sensor applications.