Over recent years Silicon photonic crystals have received great attention due to their strong potential applications in the field of integrated optics. Optical resonators formed by defects into 2D photonic crystals are capable of localizing light and can exhibit high-Q modes. The cavity mode frequency of such structures can be tailored by careful design of their structural parameters and is highly sensitive to the refractive index of the environment. An adsorption of biomolecules on the surface changes locally the refractive index and, therefore, affects the resonant wavelength of the cavity. This enables sensing in ultra small volumes. Furthermore, many photonic crystal sensors can be readily integrated onto a chip and combined with optical routing elements making these structures adaptable for lab-on-chip applications. We take advantage of these properties and report label-free biosensing based on photonic crystal nanocavities.
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