Nanofocusing of light into semiconducting fin photonic crystals

• Published in: Applied physics letters 2016-02, Vol.108 (8)
• Main Authors: Bogdanowicz, J., Nuytten, T., Gawlik, A., Schulze, A., De Wolf, I., Vandervorst, W.
• Format: Article
• Language: English
• Subjects: Applied physics; Electromagnetic fields; Fins; Incident light; Periodic structures; Photonic crystals; Raman spectroscopy; Semiconductor devices
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4942603

This letter demonstrates experimentally and investigates theoretically the possibility for enhanced light coupling into periodic arrays of nanoscale semiconducting fins. Using Raman spectroscopy, we show that an electromagnetic field impinging upon such periodic structures can be confined into the semiconducting regions when the ratio W/λ0 of the fin width to the incident wavelength is sufficiently small and when the incident light polarization is parallel to the fin edges. As we demonstrate based on band structure calculations and finite-element simulations, this corresponds to the availability and excitation of a dielectric-band mode of the constituted photonic crystal waveguide, i.e., a mode guided inside the semiconducting fins. The understanding of this nanofocusing behavior opens the way to a plethora of applications including the optical metrology of deep-subwavelength non-planar semiconductor devices.