Supercontinuum generation in ultra-flattened near-zero dispersion PCF with C7H8 infiltration

摘要

A novel design study of ultra-flattened near-zero dispersion PCF with toluene (C7H8) infiltration is proposed. The near-zero ultra-flattened dispersion is achieved by appropriately reducing the diameter of the first ring air-holes in the cladding and increasing the distance from the core to these air-holes. An ultra-flattened chromatic dispersion as small as 0.947 ps/(nm.km) has been obtained over a broadband of 500 nm with a high nonlinear coefficient and very low attenuation of the fundamental modes (about 10(-14) dB/m at the pump wavelength). Two optimized PCFs have been selected for broad-spectrum supercontinuum (SC) generation with low peak power. The first fiber with a lattice constant (lambda) 0.9 mu m and filling factor (d(1)/lambda) 0.45 has an anomalous dispersion regime. The SC spectrum broadens from 800 to 2800 nm with a full width at half maximum (FWHM) of 1897.3 nm generated by pump pulses centered at a wavelength of 1.55 mu m, with input pulse energy of 0.05 nJ and 90 fs duration, corresponding to the peak power of about 0.556 kW. The second proposed fiber (lambda = 1.0 mu m, d(1)/lambda = 0.5) enables SC generation in an all-normal dispersion regime with an FWHM of 1163.7 nm at the same pump pulses as the first fiber with input pulse energy of 0.015 nJ (the peak power of 0.375 kW) in a 5 dB dynamic range. These fibers can be a new class for the next generation of broadband laser sources with a low peak power as cost-effective alternatives to glass core fibers.