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HL: Fachverband Halbleiterphysik
HL 58: Photonic Crystals: Experiment
HL 58.7: Vortrag
Donnerstag, 25. März 2010, 17:30–17:45, H13
Strain dependence of second harmonic generation in silicon — •Clemens Schriever1, Christian Bohley1, Jörg Schilling1, and Ralf Wehrspohn2 — 1ZIK "Sili-nano", Martin-Luther-University Halle — 2Martin-Luther-University Halle Wittenberg
In recent years, silicon has become a favored material in photonics, mainly due to its highly optimized CMOS processing technology and its suitable optical properties at telecommunication wavelengths. Here it has proven itself as passive optical component. The difficulty of integrating silicon into active optoelectronics, where electrical and optical functionalities are combined in a monolithic device is due to its limited active optical properties. Generally, second order nonlinear optical effects like second harmonic generation are forbidden in silicon because of its inversion symmetry. However, an induced inhomogeneous strain can reduce the symmetry of the crystal and therefore give rise to a second order nonlinear susceptibility. This opens the possibility to create silicon based active optical devices, e.g. electro-optical modulators and switches. Here we determine experimentally the strain dependence of the second order nonlinear susceptibility on the applied strain by means of second harmonic generation in a reflecting geometry. The components of the second order nonlinear susceptibility are determined and compared to the unstrained case. The results agree well with theoretical predictions that take into account the applied strain. There, an analytical dependence of the second order nonlinear susceptibility on the strain is derived from an sp3-orbital concept.