Single-modeness of short large mode area fibers: an experimental study

We experimentally investigated the limits to the endlessly single-modeness of large mode area photonic crystal fibers. We analyzed two versions of a commercial large mode area fiber with equal structural parameters but five or seven confining rings, and in both cases we found that the single mode regime becomes critical for short (1 m) fibers. The same results were observed in large mode area fibers with different core sizes