Large Mode Area Passive Fibers LIEKKI® passive fibers are especially designed and manufactured to match the optical guiding properties of LIEKKI ® large mode area Ytterbium doped fibers. This enables optimal mode coupling with minimal splice loss for maintaining the power and excellent beam quality between all elements of a fiber laser or amplifier. High-quality Fiber Bragg Gratings can be written into all LIEKKI® passive fibers. LIEKKI® passive fibers are available in single cladding, double cladding (DC), single cladding polarization maintaining (PM) and double cladding polarization maintaining configurations. • realNA — most accurate fiber core NA to enable superior predictability of fiber performance and minimal splice loss • Pigtails for fiber lasers and amplifiers • Matching with industry standard active fiber geometries 125, 250, 400 μm • All-fiber subassemblies • Glass cladding diameter is designed to “fit-in” octagonal active fibers • High brightness power delivery • Low signal and pump coupling losses from passive to active fiber • Fiber based components for fiber lasers (e.g. pump combiners; FBGs) • Single cladding fibers feature a dual coated high-index acrylate coating • Double cladding fibers feature a NA ≥0.48 low-index fluoroacrylate coating, which is proven to operate up to 120˚C and in extreme humidity. • Fiber Bragg Gratings can be written into all large mode area passive fibers

Large Mode Area Passive Fibers Core, cladding and coating diameters specified in m. realNA 3 Proof test level specified in kpsi. 4 Core diameter specification refers to the far-field mode field diameter at 1060 nm. 2 Matching Active Fiber

Large Mode Area Passive Fibers Core, cladding and coating diameters specified in m. realNA 3 Proof test level specified in kpsi. 4 Core diameter specification refers to the far-field mode field diameter at 1060 nm. 2 Matching Active Fiber