Progress on low loss photonic crystal fibers

Photonic crystal fibers (PCF) with a silica-air microstructure have received increasing attention in recent years. In this paper, we analyze the loss properties of PCF and report our progress on low loss PCF. We show that the loss performance of PCF is dominated by scattering loss and OH− absorption loss. We show that the PCF scattering loss depends on both the roughness of the hole interior surface and the power distribution in the fiber cross-section. By employing appropriate polishing, etching and dehydration processes, we succeeded in obtaining a PCF with an OH− absorption loss as low as 0.4 dB/km at 1.38 μm and another PCF with a loss of 0.28 dB/km at a wavelength of 1.55 μm, which are the lowest values to the best of our knowledge.