Highly efficient fluorescence sensing with hollow core photonic crystal fibers

We investigate the potential of microstructured optical fibers ( MOFs) for highly sensitive absorption and fluorescence measurements by infiltrating a dye solution in the holey structure. Generally in a MOF only the evanescent part of the electromagnetic field penetrates into the sample material, providing a weak light-matter interaction. We compare such a MOF with a selectively filled hollow core photonic crystal fiber (HCPCF), in which most of the field energy propagates in the sample material. We show that dye concentrations down to 1 x 10(-10) M can be detected in a HCPCF using only nanoliter sample volumes. Our experiments proof that HCPCFs are well suited for demanding sensing applications, outperforming existing fiber tools that rely on evanescent sensing. (C) 2007 Optical Society of America.