DC and AC Electro‐Optic Responses of Efficient and Thermally Stable Guest–Host Polymers by Attenuated Total Reflection Technique

Recent advances in push–pull heptamethine chromophores (PPH‐phores) featuring large first hyperpolarizabilities, combined with chemical stability and scalable synthesis, mark a milestone in the development of organic electro‐optic (EO) materials. However, incorporating these PPH‐phores into optical polymers with high glass transition temperatures ( T g ) remains challenging. Major obstacles include designing compatible guest‐host systems, controlling high‐field poling process, and establishing reliable methods to quantify EO performance in poled polymer films. This study formulates and compares two benchmark push‐pull chromophores: M1a‐FP‐ON , a representative PPH‐phore, and AJLZ53 , a push‐pull tetraene chromophore, incorporated individually or jointly into poly(bisphenol A carbonate) ( PC ) to create high‐ T g guest‐host polymers. EO properties were systematically characterized in slab waveguides using a lock‐in‐free attenuated total reflection (ATR) technique, enabling precise determination of EO coefficients under DC and AC voltages. The results demonstrated large r 33 values, up to 125 pm/V at 1306 nm, among the highest ATR‐verified activity reported for guest‐host EO polymers with modest chromophore loading, along with excellent thermal stability for both single‐ and binary‐chromophore systems. These findings highlight the critical role of chromophore structure and ATR technique in determining EO responses of poled polymers, offering valuable insights into designing new high‐ T g EO polymers for photonic applications.