High-Birefringence and Quarter-Wave Plates at 1550 nm Using Azopolymers

Azobenzenes are a class of compounds which allow the writing and erasure of linear birefringence along any desired direction, through their ability to photoisomerize. This property enables applications requiring polarization control, which, despite extensive exploration in the visible spectrum, have yet to be fully capitalized in the infrared region. This study aims to systematically characterize the creation and relaxation of induced linear birefringence dynamics in azopolymers thin films for the 1550 nm region. Maximum birefringence values as high as 6.02 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> were attained during the recording phase with a 445 nm pump laser, that stabilized at 5.40 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> during the relaxation phase, achieved for a 2.4 μ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> sample. In addition, a maximum phase shift of ΔΦ = 0.54π stabilizing at ΔΦ = 0.50π, was observed for a 9.7 μ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> sample with a 532 nm writing laser. Accordingly, this shows the promising potential of azopolymers for many applications.