Interlayer air-hole photonic crystal fiber with flat dispersion and three zero dispersion wavelengths for supercontinuum generation

Abstract

This paper proposes an Interlayer Air-hole Photonic Crystal Fiber (IA-PCF) consisting of five air-hole layers with a single material, which means compatibility checking between the core and cladding material need not be required. The optical fiber is designed using COMSOL software. Further more, the dispersion, nonlinearity, effective mode area, and confinement loss characteristics of the proposed IA-PCF structure are numerically analyzed using the finite element method (FEM). The results indicate that the proposed IA-PCF has three zero dispersion wavelengths (ZDW) within 800–2400 nm. Through continuous structural optimization, a flat dispersion optimal IA-PCF with a dispersion fluctuation of ± 2.05 (ps/nm·km) in the range of 1509 nm-1955 nm is obtained. The three zero dispersion wavelengths (ZDW) of the optimal IA-PCF are 1061 nm, 1598 nm, and 1904 nm, respectively. Four input 50 fs pulses both in the normal and anomalous dispersion regimes are explored to analyze the spectral evolution process of SC in a 30 cm lenth IA-PCF. The results indicate that the continuous SC exists in the range of 750 nm-2430 nm at the pump wavelength of 1064 nm with power range of −40 dB. While the continuous broadband SC exists in the range of 1235 nm-3470 nm at the pump wavelength of 1550 nm with power range of −43 dB. In addition, a broadband, flat SC spectrum with a power range of −26.8 dB to −18.6 dB is obtained in the wavelength range of 1331 nm-2315 nm at a pump wavelength of 1080 nm. The IA-PCF provides a new structure and approach for generating a broadband, flat and SC spectrum. The supercontinuum belongs to a wide range of applications in optical communication, optical coherence tomography, optical frequency comb etc.