Nonlinear absorption in InN under resonant- and non-resonant excitation

Hyeyoung Ahn*, M. T. Lee, Y. M. Chang, J. L. Peng, S. Gwo

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


We report the wavelength-dependent nonlinear absorption (NLA) of InN film grown on anr-plane sapphire by molecular beam epitaxy technique. In order to understand the nonlinear optical properties of InN, the Z-scan measurement was performed at two different wavelengths, the photon energies of which are near (resonant excitation) and much higher (non-resonant excitation) than the bandgap of InN, respectively. Under non-resonant excitation, band-filling effect leads the dominant saturable absorption, while under resonant excitation, reverse saturable absorption dominates the nonlinear absorption. From the open-aperture Z-scan measurement under resonant excitation, we found that InN exhibits more than one nonlinear absorption process simultaneously. Particularly, under relatively weak resonant excitation, the transformation from saturable absorption to 2PA through the intermediate excitation state absorption was observed as the sample approaches the beam focus. The close-aperture Z-scan signals of InN show valley-peak response, implying that the nonlinear refraction in InN is caused by the self-focusing of the Gaussian laser beam. Using the Z-scan theory, the corresponding nonlinear parameters, such as saturation intensity, 2PA coefficient, and nonlinear refractive index, of InN were estimated.

Original languageEnglish
Title of host publicationGallium Nitride Materials and Devices VIII
StatePublished - 12 Jun 2013
EventSPIE Symposium on Gallium Nitride Materials and Devices VIII - San Francisco, CA, United States
Duration: 4 Feb 20137 Feb 2013

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceSPIE Symposium on Gallium Nitride Materials and Devices VIII
CountryUnited States
CitySan Francisco, CA


  • Indium nitride
  • Nonlinear absorption
  • Z-scan technology

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