We demonstrate low-loss anamorphic transitions between circular and rectangular fiber cores with aspect ratios up to 5:1, and hence improved coupling from a diode laser by using only a spherical lens. Differential hole pressurization and localized heating of a stock photonic crystal fiber inflates the holes at different rates. Some holes are plugged in the fiber end face where pressure is applied, so they remain at ambient pressure. Alternatively, holes of different sizes expand at different rates because the effective pressure due to surface tension differs.
© 2006 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: June 13, 2006
Manuscript Accepted: June 24, 2006
Published: August 25, 2006
A. Witkowska, K. Lai, S. G. Leon-Saval, W. J. Wadsworth, and T. A. Birks, "All-fiber anamorphic core-shape transitions," Opt. Lett. 31, 2672-2674 (2006)