Ambient Air Ageing Effect on Vapour-Chopped Polyaniline Thin Film Optical Waveguide for Integrated Optics

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ABSTRACT

Polyaniline (PANI) was synthesized initially as a powder in an acidic medium by oxidation polymerization and used for vacuum evaporation on an optical flat glass substrate. This paper reports the effect of ambient air ageing (30 days at room temperature) on optical, mechanical and optical waveguide transmission loss properties of PANI thin film. The vapour chopping technique was successfully used for reducing the optical transmission loss, refractive index, intrinsic stress and increasing adhesion of the waveguide film. Both (as-deposited and vapour-chopped) thin films showed oxime-type PANI structure after ageing. The vapour-chopped film (2.45 – 3.69 dB/cm) showed a small optical transmission loss change as compared to the as-deposited thin film waveguide (3.18 – 5.08 dB/cm) after ageing. The air ageing caused to increase in refractive index, optical transmission loss and a decrease in adhesion and intrinsic stress but the effect was found to be lesser in vapour-chopped PANI thin film.

Significance of the study:

The research highlights the effectiveness of the vapour chopping technique in mitigating the adverse effects of ambient air ageing on PANI thin films. This method significantly reduces optical transmission loss and intrinsic stress while enhancing film adhesion and stability. The simple and cost-effective technique offers a promising approach for producing high-quality optical waveguide films, advancing the development of integrated optics.

Summary of the study:

This study investigates the ambient air ageing effects on polyaniline (PANI) thin films, synthesized via oxidation polymerization and deposited on glass substrates through vacuum evaporation. The vapour chopping technique was employed to enhance film properties. After 30 days of air ageing, vapour-chopped films showed reduced optical transmission loss, refractive index, and intrinsic stress compared to as-deposited films, demonstrating improved stability and performance for optical waveguide applications.