Nonpoled polymeric films doped withblue-window pyrylium salt dyes forsecond-harmonic-generation devices

We have prepared polymer films doped with novel nonlinear organic ionic materials, pyrylium salt dyes, and have investigated the second-order nonlinear optical properties of these guest–host-type polymer films by changing the counterion and alkyl group derivatives. These films have no absorption in the blue-light region and have second-harmonic-generation activity without electric-field poling. The second-order nonlinearity of the nonpoled-polymer film is constant, with no relaxation at room temperature or at high temperatures. We fabricated a second-harmonic-generation device with the nonpoled-polymer film and observed Cerenkov-type phase-matched second-harmonic-generation of a Nd:YAG laser.