Photonic crystal-enhanced fluorescence through the extraction of dually polarized modes

In this Letter, we demonstrate that fluorescence detection by using surface-bound fluorescent molecules can be enhanced by coupling the fluorescence emission with dually polarized resonant modes of a photonic crystal (PC) substrate. The PC was fabricated through nanoreplica molding by using a plastic substrate. It was designed such that the transverse magnetic (TM)- and transverse electric (TE)-polarized resonance coincided at a specific combination of the incident angle and the illumination wavelength. During excitation, the nonpolarized emission from cyanine-5 was simultaneously coupled with the TE and TM resonant modes and reradiated into the detection instrument, increasing the fluorescence collection efficiency and thus, enhancing the fluorescence detection.