LIEKKI™ passive fibers are available as large mode area (LMA) fibers and  multi-mode fibers. LIEKKI™ LMA passive fibers match the standard LIEKKI active fibers, which have matching passive double cladding (DC) fiber.  Most of the standard active fibers also have the matching passive non-DC fiber.  Passive fibers are matched to the fiber core diameter and numerical aperture of the active counterparts so that excellent beam quality is maintained throughout the fiber laser or amplifier. Polarization maintaining (PM) fibers are also available for the range of standard PM active fibers. Many of the LMA passive fibers are suitable for Fiber Bragg Grating manufacturing, and are all suitable for combiner manufacturing.