Supercontinuum generation in photonic crystal fibres with core filled with toluene

Abstract

A photonic crystal fibre with hollow core filled with toluene is considered as a new system for coherent supercontinuum generation. The dispersion characteristics are studied for various geometrical parameters of photonic crystal fibres. Two structures with lattice constant 2 μm, filling factors d/Λ 0.3 and 0.35 and toluene core of diameters of 3.34 and 3.23 μm have flat dispersion in the near infrared range. The structure with d/Λ=0.3 has all-normal dispersion characteristics in whole near-infrared wavelength range, while the second structure (d/Λ=0.35) has anomalous dispersion for wavelengths longer than 1.5 μm. Although confinement losses in the considered structures are as high as 0.4 dB cm −1 , we show that the generation of coherent supercontinuum in the range 1.0-1.7 μm with the pulse energy conversion of 16% is feasible in 4 cm long fibre samples with standard fibre femtosecond lasers.

Feature Properties of Photonic Crystal Fiber with Hollow Core Filled Nitrobenzene

“…3, we presented the effective refractive index n eff of fundamental modes simulated for PCF-N having structures with lattice constants Λ = 2.0 µm and Λ = 2.5 µm and filling factor d/Λ varies from 0.3 to 0.8. The effective refractive index curves are similar to the results obtained for PCF with hollow core infiltrated with Toluene [28].…”

“…The target structures of PCF in this study are similar to those presented in previous work [28], except for the infiltrating liquid Toluene replaced by Nitrobenzene. Its geometrical structure is simulated and presented in Fig.…”

“…Since the lattice constants are unchanged, the appearance of curves of Re[n eff ] is seen to be similar for both cases of PCF-N and PCF-T [28], but their magnitudes at a given wavelength are clearly different, which are listed in Table 2, as an example for a wavelength of 1.55 µm. In all of simulated cases, the effective refractive index of PCF-N is greater than that of PCF-T.…”

“…In recent years, PCFs with air holes have been infiltrated with liquids having different refractive index and higher nonlinearity on the cladding or the core of photonic crystals fiber as designing a dual-core PCF coupler [24], D-glucose sensor using PCF [25], dispersion engineering of photonic crystal fibers by means of fluidic infiltration [26], liquid-filled simplified hollow-core PCF [27]. Infiltration with liquids on the core the PCF has a high loss limitation, but it has an advantage that the nonlinearity is higher, since the fundamental mode is very well confined in the PCF core [28]. This property makes PCF to be the good medium for supercontinuum generation [29][30][31].…”

“…The PCF with hollow-core infiltrated with Toluene (PCF-T) has been proposed and investigated in detail [28]. Two optimal structures with the same lattice constant Λ = 2 µm but diferent filling factors d/Λ = 0.3 and 0.35 are analyzed and discussed for supercontinuum generation.…”