SHG Relaxation Behaviour In M-nitroaniline Doped PMMA Guest-host System

R.K Goyal,Y.S Negi,S.R Damkale,J W Dadge,R.C Aiyer,U.P Mulik

doi:10.5185/amlett.2010.8150

Abstract

In present work, we have reported the second harmonic generation (SHG) property on the Guest-Host system based on optical grade poly(methyl methacrylate) (PMMA) and m-Nitroaniline (m-NA) for their use in optoelectronic devices. SHG signal of the m-NA doped PMMA freestanding films was determined using Nd:YAG laser by varying input energy from 6 mJ to 18 mJ. For evaluating SHG, films were poled at various temperatures to align the m-NA guest molecules in PMMA host matrix. Doped films were also characterized isothermally by thermogravimetric analysis (TGA) to get the information about loss of m-NA molecules at poling temperatures. It was found that there is no change in glass transition temperature. SHG intensity increases as the poling temperature increases. However, SHG signal intensity decreases as the decay time of poled films increases. After one week of poling more than half of the original SHG intensity is retained. The decay in SHG intensity might be attributed to the relaxation of m-NA molecules from thermodynamic unstable state to the equilibrium state.

Highlights

Polymeric guest-host systems have been emerged as strong candidates for various futuristic optoelectronic devices in comparison to their inorganic counterparts due to their large optical non-linearity, lower dielectric constant, ultrafast and broadband electronic responses
To the best of our knowledge, first time we report the effect of poling temperature on second harmonic generation (SHG) intensity and relaxation of SHG intensity at room temperature with respect to time
The samples were cooled to room temperature and the poling field was subsequently removed, which results in a system where the dipole moment of m-NA guest molecule is aligned in the electric field direction within the poly(methyl methacrylate) (PMMA) host matrix

Summary

Introduction

Polymeric guest-host systems have been emerged as strong candidates for various futuristic optoelectronic devices in comparison to their inorganic counterparts due to their large optical non-linearity, lower dielectric constant, ultrafast and broadband electronic responses. Negi received Ph.D. in Polymer Science from Indian Institute of Technology Delhi, India in 1983. His main research interests are nonlinear optical properties of nanomaterials and chromophore doped polymers.

Results

Conclusion