Terahertz (THz) radiation characteristics have been investigated for voltage-biased photoswitching devices (PSDs) coupled with dipole antennas made on magnetoresistive Pr0.7Ca0.3MnO3 thin films. Even under a fixed illumination of femtosecond laser pulses with a power of 14 µJ/cm2, we find the high electric strength in PSDs made on Pr0.7Ca0.3MnO3 thin films in the charge-ordered (CO) state at 10 K. THz radiation linearly enhances with an increase of the biased electric field up to 400 kV/cm without any change of the waveform of the radiated THz pulse. On the other hand, the static time-averaged photoconductance is nearly constant below 200 kV/cm but deviates from it above 200 kV/cm. Such behavior can be ascribed to an increase in the change of the fraction of photogenerated metallic patches within the CO insulating phase. Therefore our findings show that not only Pr0.7Ca0.3MnO3 but also other manganites having a CO state above room temperature may act as efficient THz radiation sources.
© 2006 Optical Society of America
(310.6860) Thin films : Thin films, optical properties
(320.7080) Ultrafast optics : Ultrafast devices
(320.7130) Ultrafast optics : Ultrafast processes in condensed matter, including semiconductors
Vol. 1, Iss. 2 Virtual Journal for Biomedical Optics
Noriaki Kida and Masayoshi Tonouchi, "Terahertz radiation from magnetoresistive Pr0.7Ca0.3MnO3 thin films under strong electric fields," J. Opt. Soc. Am. B 23, 179-182 (2006)