In this paper, we investigate the beam quality of photonic-crystal fibers (PCFs) with one, three, and seven missing airholes. The beam quality factor mmb M2 of a PCF is generally larger than unity, even if it is single mode. The results are especially important for the design and measurements of single-mode PCF lasers. A comparison between an mmb M2 measurement of the laser beam and the reported numbers can establish whether a PCF laser is operating as single mode or is contaminated by higher order modes.
© 2005 IEEE
Arash Mafi and Jerome V. Moloney, "Beam Quality of Photonic-Crystal Fibers," J. Lightwave Technol. 23, 2267- (2005)