A study on polarization dependence of quadratic photocurrent in light emitting diodes using real time cross-polarized autocorrelation signals

An experimental study on the polarization dependence of the quadratic photocurrent in commercial light emitting diodes (LEDs) has been carried out using 200 fs laser pulses from a cw mode-locked Nd:glass oscillator. The variation of induced quadratic current with respect to orientation of polarization of the laser beam is measured using single and double beams. Cross-polarized autocorrelation measurements have been performed in real time at different orientations of the LEDs to differentiate the contributions to the quadratic photocurrent of two-photon absorption and second harmonic generation. The theoretical analysis of cross-polarized signals under different orientations is presented. PACS 42.65.Re; 42.65.ky; 42.50.Hz; 85.60.Jb