Terahertz emission from indium oxide films on MgO substrates excited at a photon energy below the bandgap

Indium oxide (In 2 O 3 ) films grown on MgO substrates by thermal oxidation were excited by femtosecond laser pulses having photon energy lower than the bandgap. The emission of terahertz (THz) pulse was observed using time domain spectroscopy in the reflection-geometry excitation. Results show that...

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Bibliographic Details
Main Authors: Estacio, E., Que, C. T., Awitan, F. C. B., Bugante, J. I., De Vera, C., Azares, J., de Vero, J., Somintac, A. S., Sarmago, R. V., Salvador, A. A., Yamamoto, K., Tani, M.
Format: Conference Proceeding
Language:English
Subjects:
Indium
Optical films
Oxidation
Photonic band gap
Substrates
Ultrafast optics
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Summary:Indium oxide (In 2 O 3 ) films grown on MgO substrates by thermal oxidation were excited by femtosecond laser pulses having photon energy lower than the bandgap. The emission of terahertz (THz) pulse was observed using time domain spectroscopy in the reflection-geometry excitation. Results show that THz generation saturates at an excitation fluence of ~400 nJ/cm 2 . Although two-photon absorption has been ruled out, the actual THz emission mechanism and still has to be verified and is temporarily attributed to carriers from defect level absorption possibly being driven by a strain field due to the lattice mismatch between the In 2 O 3 and the MgO substrate.
DOI:10.1109/IQEC-CLEO.2011.6193807