Efficient Free-Space Coupling to LMA-PCF by Aberration Correction

A scheme is presented here to lower the free-space coupling loss to large mode area (LMA) photonic crystal fiber (PCF). A numerical study (using optics software for layout and optimization/beam propagation method) has been performed which demonstrates that the major source of coupling loss is due to the aberrations present in the optical system (using bulk optics) creating a source beam with appropriate size to couple into the LMA-35. We show that by carefully choosing a single or multiple aspheric lenses the wavefront aberrations can be minimized and the coupling loss into the LMA-PCF can be reduced to only 0.5 dB.