Figure 3.

Optical properties of porous silicon colloids. Measured optical transmittance of a 1.910-μm-diameter porous silicon sphere (black curve). The Mie theory fit (red curve) gives a refractive index of 1.8 in all the measured range. The resonant modes are indicated under their corresponding deeps by letters ‘a’ (for transversal magnetic modes) and ‘b’ (for transversal electric modes) and two sub-indexes that account for the different electric field intensity distributions.