Optical bistability in colloidal solution of Er-Yb doped LaF3 nanocrystals

In this paper, we report the investigation of the optical bistability and hysteresis in the device based on phase conjugated mirror in colloidal solution of LaF₃: Er,Yb nanocrystals. Oleic acid (OA)-modified LaF₃: Er,Yb nanocrystals have been prepared by a phase transfer and separation mechanism occurring at the interfaces of the liquid, solid and solution phases present during the synthesis [1]. We chose 20% (molar ratio) Yb³⁺ ions as codoping concentration in the preparation of the nanocrystals. The obtained nanocrystals was redistributed in carbon tetrachloride (CCl₄) which was used as the solvent based on following three factors: (1) it does not exhibit absorption bands in NIR region because of its low fundamental vibration energy, (2) it eliminates any residual H₂O that serves as an effective quencher for NIR emission, and (3) it has a relatively high refractive index compared with other non-polar solvents and therefore minimizes loss of light due to Rayleigh scattering.