Optical second harmonic generation in radio-frequency sputter-deposited AlN thin films has been studied for harmonic wavelengths from ultraviolet to near infrared. The effective second-order nonlinearity χ(2)(ω) was determined to have a nonresonant background value of ∼5×10 -9 esu for second harmonic wavelengths longer than 400 nm, and it increases dramatically as the second harmonic frequency approaches the bandgap of 6.2 eV. This is likely due to resonance of the second harmonic frequency with the critical point transition associated with the direct bandgap of AlN.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)