Spatial phase filtering based on the intensity-dependent refractive index of PbS nanocomposite film

Abstract

We demonstrate the use of stable films containing PbS nanocrystals as media for self-adaptive phase filtering in phase contrast imaging of transparent objects by a cost-effective exploitation of nonlinear optical refraction in a simple, all-optical, and self-adjusting 4f imaging system. The optical nonlinearity is characterized by z-scan technique using a continuous wave He-Ne laser as the excitation source. The mechanism of nonlinearity in this case is mainly due to the nonlocal thermo-optical interaction between the laser beam and the sample. The value of nonlinear refractive index coefficient is found to be -3.5x10(-7) cm(2)/W. The nanocomposite material shows a thermal lens effect and is a potential candidate for phase contrast imaging.

Epitaxial Growth of PbS Nanocrystals from PbI2 Nanosheet Templates and Its Application in Fast Near‐Infrared Photodetectors

“…In the same display mode, the color of flake surface changes from cyan to purple, indicating a certain reaction on the surface, which is because the refractive index and absorption spectrum of the PbS NCs are different than those of initial PbI 2 (Figure 1c). [ 23,24 ] Further, the surface of the entire heterojunction is still smooth and flat in the macroscopic view, which can be verified from the scanning electron microscopy (SEM) image. To systematically examine the growth mechanism of heterostructure, the concentration of the Na 2 S solution and reaction time were tuned to control the growth process.…”