Polarized optical absorption and photoluminescence measurements in single-crystal thin films of 4(')-dimethylamino-N-methyl-4-stilbazolium tosylate

Single-crystal thin films of the anhydrous (red) and the hydrated (orange) phases of the organic salt 4'-dimethylamino-N-methyl-4-stilbazolium tosylat e were grown by a modification of the shear method. The optical absorption coefficients of the films were measured with light polarized along and norm al to the dipole/molecular axis at both resonant and off-resonant wavelengt hs, and a strong dichroism was observed at the resonant wavelengths. The ab sorption measurements are important considering potential applications of t hese films (red phase) in high-speed single-pass thin-film electro-optic mo dulators [M. Thakur, J. Xu, A. Bhowmik, and L. Zhou, Appl. Phys. Lett. 74, 635 (1999)] and other photonic devices. Highly polarized photoluminescence (PL) has been observed in these films. The PL efficiencies of the red- and orange-phase single-crystal films were measured to be about 12% and 14%, re spectively, which are significantly higher than the maximum PL efficiency m easured in solution (3%). (C) 1999 American Institute of Physics. [S0003-69 51(99)01447-3].