Dispersion-engineered segmented core rib waveguide for coherent and broadband supercontinuum generation in both all-normal and anomalous regimes

Abstract

We present a novel, dispersion engineered, segmented core rib waveguide for broadband, highly coherent and flat supercontinuum generation in both all-normal and anomalous dispersion regime. The waveguide uses Aluminum Gallium Arsenide, known as “silicon of non-linear optics”, as the core material. To achieve a flat and low dispersion profile, we employed dispersion engineering by optimizing the geometrical parameters of the waveguide. The optimized design features an all normal, flat top dispersion profile with values below—4.43 ps/nm/km across the spectral range of 4.8–7 µm achieving a dispersion value of − 1.71 ps/nm/km at the pump wavelength of 5 µm. Our simulation study, employing the split step Fourier transform method results in coherent supercontinuum spectrum broadening from 2 to 12 µm (40 dB level) and 2.1 to 9.8 µm (20 dB level) in 3 mm long waveguide when pumped with 5 µm secant hyperbolic pulses having pulse width 50 fs and peak power 6 kW. To the best of our knowledge, such broadband supercontinuum spectrum in mid-infrared region at the 20 dB level using waveguide geometry has been reported for the first time. Additionally, when pumped in anomalous dispersion region at 6 µm, our simulations result in supercontinuum broadening from 2.6 to 16 µm (40 dB level) in mid-infrared region under identical laser operating conditions. The proposed waveguide can serve as a promising candidate for on-chip supercontinuum sources and for diverse applications like frequency comb generation, early cancer diagnostic, chemical sensing and food-quality control.