Time-Resolved Investigation of Photoinduced Birefringence in Azobenzene Side-Chain Polyester Films

Abstract

We present time-resolved measurements of photoinduced birefringence in liquid crystalline polyester films. After excitation with a single nanosecond pulse, the induced birefringence is monitored on time scales ranging from nanoseconds up to minutes. The maximum birefringence is attained in a dark reaction after excitation. Subsequently, most of the induced birefringence is lost due to relaxation processes involving up to four different time constants. We observed that at high pulse energies the relaxation characteristics are strongly influenced by thermal effects.