Design of a low power optical limiter based on a new nanocomposite material incorporating silica-encapsulated phthalocyanine in Nafion

Abstract

We report on the design of a stable optical limiter in the low laser power regime based on the thermal variation of refractive index in a novel nanocomposite material. The optical material, chloroaluminium-phthalocyanine (ClAlPc), is embedded in SiO2-Nafion nanocomposite membrane (ClSNf) and its thermally induced nonlinear refractive index is characterized by the Z-scan technique with a low power cw He–Ne laser as the source. The value of nonlinear refractive index coefficient, n2, is found to be about 1.11 × 10−11 m2 W−1. The experiment is repeated with the dye doped in pure Nafion membrane (ClNf) and the results are compared with those of ClAlPc doped SiO2–Nafion nanocomposite membrane. The value of n2 is found to be 1.36 × 10−11 m2 W−1 and is larger than that of the ClAlPc embedded SiO2–Nafion nanocomposite membrane. The photostability of the dye-embedded membrane is studied by exposing the sample to cw He–Ne laser and monitoring its fluorescence emission intensity continuously. The samples are found to show large thermal lens effect and demonstrated to be good optical limiters in the low power regime. Whereas the optical properties of dye-doped Nafion appear to be slightly better than those of the dye embedded in silica and incorporated in Nafion, the latter is found to offer excellent photostability.

Nonlinear optical behaviour of indium-phthalocyanine tethered to magnetite or silica nanoparticles

“…[29][30][31][32][33] Sathiyamoorthy et al reported on the improved optical limiting behaviour by nonlinear refraction for chloroaluminium phthalocyanine (ClAlPc)-doped Nafion (without silica) compared to the silica-encapsulated ClAlPc-doped Nafion. 34 However, in a separate study on ClAlPc coated by silica shell via a sol-gel method, 35 an improved optical limiting behaviour was observed for the ClAlPc-doped silica shell compared to ClAlPc alone. 36 This makes us believe that the observed decrease in the nonlinear optical properties of the silica-encapsulated ClAlPc-doped Nafion compared to the ClAlPc-doped Nafion without silica might be due to some interactions (which hinder effective nonlinear refraction) between the silica structures and the Nafion.…”

Nonlinear Refraction and Absorption Phenomena in a Novel Nanocomposite Based on a Dye Stabilized in a Solid Hybrid Matrix

“…However, thermal mechanism could also contribute to some extent in such systems under nanosecond excitation at the pulse repetition rate of 10 Hz as the response time of such samples is expected to be of the order of a few milliseconds. 46,47 E. Photostability. The optical stability of the materials is monitored by recording the optical absorption spectra of the samples as they are kept in the ambient environment for several months.…”

Thermo-optic nonlinear response of silver nanoparticle colloids under a low power laser irradiation at 532 nm

“…This may lead to a large spatial nonlocality on the refractive index changes of the medium. The thermal lens phenomenon has been shown to contribute to significant extent to the nonlinear optical response of composite media containing metal nanoparticles 11–13. Large enhancement factors were observed for thermal nonlinear refractive index and thermo‐optic coefficients of the colloid due to the presence of gold nanoparticles 11, 12.…”