R. Hollinger,
D. Gupta,
M. Zapf,
M. Karst,
R. Röder,
I. Uschmann,
U. Reislöhner,
D. Kartashov,
C. Ronning,
and C. Spielmann
Polarization dependent multiphoton absorption in ZnO thin films
J. Phys. D, 53 :055102 ( 2020)
Polarization dependent multiphoton absorption in ZnO thin films
J. Phys. D, 53 :055102 ( 2020)
Abstract:
We present a simple non-destructive approach for studying the polarization dependence of nonlinear absorption processes in semiconductors. The method is based on measuring the yield of the near UV photoluminescence as a function of polarization and intensity of femtosecond laser pulses. In particular, we investigated the polarization dependence of three photon laser absorption in intrinsic and Al-doped ZnO thin films. Both specimen show stronger emission for linearly polarized excitation compared to circular polarization. The ratios for the three-photon absorption coefficients are about 1.8 and independent of the doping. It is shown that Al-doped films have lower threshold for stimulated emission in comparison to the intrinsic films.