Porous photonic crystal external cavity laser biosensor for drug screening

We report a photonic crystal (PC) biosensor that incorporates a porous TiO
₂
film to boost sensitivity by enlarged surface area and enhanced interaction with the resonant electromagnetic fields. In the context of sensing small molecule interactions with proteins, the porous PC achieves 3.7x larger resonant wavelength shifts than an equivalent nonporous structure. Utilizing the porous PC as the wavelength selective element in an external cavity laser, the system provides narrow resonant linewidth via stimulated emission, and therefore establishes sub-picometer accuracy, representing a record high figure of merit for label free optical biosensors.