Near-infrared transparent electrodes for precision Teng-Man electro-optic measurements: In ₂ O ₃ thin-film electrodes with tunable near-infrared transparency

Highly near-infrared (NIR) transparent In2 O3 thin films have been grown by ion-assisted deposition at room temperature, and the optical and electrical properties characterized. NIR transparency and the plasma edge frequency can be engineered by control of the film deposition conditions. As-deposited In2 O3 thin films were employed as transparent electrodes for direct thin film electro-optic (EO) characterization measurements via the Teng-Man technique. Using LiNbO3 as the standard, the relationship between electrode NIR transparency and Teng-Man EO measurement accuracy was evaluated. It is found that In2 O3 electrodes can be tailored to be highly NIR transparent, thus providing far more accurate Teng-Man EO coefficient quantification than tin-doped indium oxide. In addition, the EO coefficients of stilbazolium-based self-assembled superlattice thin films were directly determined for the first time using an optimized In2 O3 electrode. EO coefficients r33 of 42.2, 13.1, and 6.4 pmV are obtained at 633, 1064, and 1310 nm, respectively.