Rectangular-core large-mode-area photonic crystal fiber for high power applications: design and analysis

A rectangular-core large-mode-area photonic crystal fiber structure has been designed based on the principle of higher order mode filtering by introducing fluorine-doped material rods in the cladding region. The proposed structure has an effective-mode area of fundamental mode (FM) as large as 2147  μm2 at 1.064 μm with nominal loss of 1.36×10−2  dB/m and 9.34  dB/m at first higher order mode (FHOM), which confirms effective single-mode operation after ∼2.14  m propagation length. The same structure offers effective-mode area of 5688  μm2 at λ=1.55  μm with confinement loss of ∼6.3×10−2  dB/m for FM and ∼20.23  dB/m for FHOM. The loss of FHOM is above 8  dB/m from λ=1  μm to λ=1.6  μm with very small loss in FM, which offers extended single-mode operation within a broad spectral range.