Modes are selectively excited by launching light through the cladding from the side into a hollow-core photonic crystal fiber. Measuring the total output power at the end of the fiber as a function of the angle of incidence of the exciting laser beam provides a powerful diagnostic for characterizing the cladding bandgap. Furthermore, various types of modes on either side of the bandgap are excited individually, and their near-field images are obtained.
© 2005 Optical Society of America
A. D. Galea, F. Couny, S. Coupland, P. J. Roberts, H. Sabert, J. C. Knight, T. A. Birks, and P. St. J. Russell, "Selective mode excitation in hollow-core photonic crystal fiber," Opt. Lett. 30, 717-719 (2005)