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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.13: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Electric-field-induced second harmonic generation in amorphous materials for hybrid photonic structures — •Laurids Wardenberg, Benito Bunk, and Jörg Schilling — Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany

We investigate electric-field-induced second harmonic generation (EFISH) on different amorphous materials, e.g a-Si and As₂S₃ films. These materials have sizeable χ⁽³⁾ values but a vanishing χ⁽²⁾ due to their amorphous structure. Applying a dc-voltage we gain the ability to create a quasi-χ⁽²⁾ and perform second order nonlinear optical processes. The possibility to manipulate value and polarity of the created quasi-χ⁽²⁾ allows an unprecedented control over these second order wavelength conversion processes. Introducing a way to electrically modulate and switch this nonlinearity, is of high practical interest for the realization of nonlinear active hybrid photonic structures.

Since EFISH is strongly associated with the χ⁽³⁾, we use the z-scan technique to determine the real and the imaginary parts of the χ⁽³⁾ of the investigated films. Subsequently chromium contacts were deposited on the films and electric fields up to 10⁵ V/m were applied. Our voltage and intensity dependent SHG measurements show a quadratic dependence on input intensity and applied DC field, which is a clear indicator for EFISH. The nonlinear optical measurements are mainly performed at a wavelength of 1030 nm using a femtosecond laser system supplying 200 fs pulses at a repetition rate of 1 kHz. Additional measurements at wavelengths above 1200 nm, which are of interest for silicon photonics, will be demonstrated as well.