Supercontinuum generation in bromotrichloromethane-filled core photonic crystal fibers

Abstract

Liquids have the advantages of a wide transparency window and high nonlinearity, which makes them a good medium for super-continuum (SC) generation. In this work, we designed and numerically investigated for the first time two photonic crystal fiber (PCF) structures with CBrCl₃ as the core and fused silica as the cladding material for broadband SC generation. The propagation of the ultrashort pulse in the proposed fibers is modeled using the generalized nonlinear Schrodinger equation (GNLSE). The first fiber #F1 with a lattice constant (Λ) of 1.5 μm and filling factor (f) of 0.35, operates with a completely normal dispersion region. By pumping a pulse source with a wavelength of 1.56 μm, an input energy of 2.5 nJ, and a pulse duration of 90 fs in a 10 cm long fiber, an ultra-broadband, and highly coherent SC spectrum is produced, covering the wavelength range from 885.3 nm to 1953.8 nm (bandwidth of 1068.5 nm) with less than 10 dB spectral dynamic range. The second proposed fiber #F2 with a lattice constant of 2.0 μm and a filling factor of 0.3, exhibits an anomalous dispersion for wavelengths longer than 1350 nm. We obtained high coherence of the SC pulses in the range of anomalous dispersion over wavelengths from 912.2 nm to 3714.8 nm (bandwidth of 2802.6 nm) within a level of 45 dB. The pump pulse here has the same wavelength as the first fiber case, but its input energy is only 1.0 nJ. Our proposed fibers open up new avenues for the development of high-brightness SC sources from the near- to mid-IR regions.