Experimental and finite-difference time-domain technique characterization of transverse in-line photonic crystal fiber

We characterize a microstructured photonic crystal fiber in the transverse direction, observing photonic bandgap effects in the transmission spectra. This is modeled using band structure and finite-difference time-domain techniques and reasonable agreement is found, confirming the observation of higher order partial photonic bandgaps. A tapered transverse bandgap fiber is used to create a reduced loss device utilizing the fundamental gap. This technique may be used to monitor the draw process for bandgap fibers, or fibers used in this way may be utilized as microphotonic elements.