Second- and third-order nonlinearities of novel push-pull azobenzene polymers

Area of Science:

• Nonlinear Optics
• Polymer Science
• Materials Science

Background:

• Push-pull side chain azobenzene polymers are crucial for nonlinear optical (NLO) applications.
• Understanding their NLO response is key to developing advanced photonic materials.
• Previous studies have explored various aspects of azobenzene NLO properties.

Purpose of the Study:

• To investigate the second- and third-order nonlinear optical response of three different push-pull side chain azobenzene polymers.
• To analyze the influence of chromophore alignment and molecular structure on NLO properties.
• To compare experimental findings with existing literature.

Main Methods:

• Spin-deposited thin films of azobenzene polymers were fabricated.
• Second- and third-harmonic Maker fringe techniques were employed.
• Measurements were conducted before and after corona poling alignment, using various polarization configurations with 30 ps laser pulses at 1064 nm.

Main Results:

• A strong dependence of the nonlinear optical response on the polymer's molecular structure was observed.
• Differences in charge transfer within the molecules were identified as the cause for varying responses.
• The alignment of chromophores via corona poling significantly influenced the NLO properties.

Conclusions:

• The molecular structure of push-pull side chain azobenzene polymers critically dictates their second- and third-order nonlinear optical response.
• Charge transfer characteristics are directly linked to the observed optical properties.
• Corona poling is an effective method for tuning the NLO behavior of these polymer films.