Analysis of hollow-core photonic bandgap fibers for evanescent wave biosensing

Hollow-core photonic bandgap fiber (HC-PBGF)-based evanescent wave biosensors are demonstrated and analyzed theoretically and experimentally. With 95% of the guided light power residing in the samples, the measured absorbance for a 30-cm-long fiber filled with a 0.2 microM Alexa Fluor 700-labeled DNA Oligo solution is 1.06. This is in good agreement with the theoretical prediction, which is evaluated by using the refractive index scaling law. The HC-PBGFs thus offer both efficiency and simplicity for the detection of biomolecules in ultra-small sample volumes.