Structure-dependent anisotropy of the photoinduced optical nonlinearity in calcium doped ZnO nanorods grown by low cost hydrothermal method for photonic device applications

• Photoinduced optical nonlinearity was measured in Calcium doped ZnO nanorods.
• Lorentz local field effect in lesser diameter rod has higher nonlinearity.
• Variation in diameter of the rod is a stress-driven process.
• Higher the absorption coefficient, higher the nonlinearity.

Calcium doped zinc oxide nanorods on ZnO seed layers were grown by hydrothermal method. Photoinduced bicolour laser treatment was done on the samples and the effective second order nonlinear coefficient (deff) has been measured. The morphology of the samples was investigated by the field emission scanning electron microscope (FESEM) images. The structural parameters acquired from X-ray diffraction (XRD) patterns have been correlated with the measured deff. The results have revealed that 15 mol% Ca doped ZnO nanorod showed maximum deff because of the Lorentz local field established along the length of the nanorod. The aspect ratio and stress play a significant role in enhancement of deff. The nonlinearity has been correlated with the absorption cross sections.