Silica segmented cladding fiber design and its fabrication using a powder-in-tube technique

A new design of segmented cladding fiber (SCF) was proposed and fabricated in silica glass. The silica glass SCF had a central core and hexagonal wings with higher refractive indices than silica cladding. The proposed SCF was analyzed numerically in terms of the confinement loss and the effective mode area using finite element method (FEM). In experiments, SCF preform was prepared by a stack-and-draw method using two types of pre-drawn rods: silica rods for the cladding and Al-doped silica rods for the higher refractive index segments and the central core. The latter was fabricated in the powder in tube (PIT) process by optimizing the heating cycles and the bubble removal during the sintering process. Light guidance along the SCF was experimentally confirmed and its intensity patterns in the near-field at the wavelengths 0.980 m and 1.550 m were characterized. With the proposed SCF, all silica SCF fabrication feasibility was confirmed, which can open a new alternative for large mode area fibers.