Highly nonlinear chalcogenide optical fibers with flattened chromatic dispersion invariant to the core fluctuation and their performances of parametric amplification

Abstract

We report here the potential of fiber optical parametric amplification (FOPA) by using highly nonlinear chalcogenide double-cladding fibers. The fibers are designed with an AsSe 2 -based core layer surrounded by two cladding layers. The size and the refractive index differences (dn) between the core and cladding are investigated to obtain flattened chromatic dispersion spectra over a wide wavelength range up to the mid-infrared window. The inner cladding with dn 2 is added to suppress the variation of the chromatic dispersion caused by the fluctuation of the core diameter. Our numerical calculations shows that very broad anomalous dispersion ranges from 5.0 μm up to 11.0 μm where the chromatic dispersion is less than 10 ps/km-nm can be obtained when the core diameter varies from 2.0 to 9.0 μm and the inner cladding diameter is kept at 9.0 μm. The dn 1 and dn 2 are 0.30 and 0.02, respectively. The FOPA calculation is carried out using a 3-cm-long fiber whose core diameter is 3 μm. When the pump power is 3 W at 5320 nm, a very broad gain bandwidth is obtained from 3.3 up to 11 μm. Moreover, the gain spectrum is flattened (about 32 ± 1 dB) in the ranges from 3.3 to 4.1 μm and from 7.5 up to 11.0 μm. When the core diameter fluctuates from 2.0 to 5.0 μm, the FOPA gain spectra can be maintained.