Silicon micromachined periodic structures for optical applications at 1.55µm

In this letter, the authors report the design, fabrication, and characterization of a silicon micromachined periodic structure for optical applications at λc=1.55 µm. The microstructure, which can be envisioned as a one-dimensional photonic crystal, is composed of a periodic array of 1-µm-thick silicon walls and 2-µm-wide air gaps, each one corresponding to a different odd number of quarter wavelength at λc (hybrid quarter wavelength). The fabrication is based on the electrochemical etching of silicon, yielding parallel trenches with depths up to 100 µm. Preliminary reflectivity measurements show the presence of a band gap at λc=1.55 µm, as theoretically expected.