Study of low-peak-power highly coherent broadband supercontinuum generation through a dispersion-engineered Si-rich silicon nitride waveguide

Abstract

Since the first observation by Alfano and Shapiro in the 1970s, supercontinuum generation study has become an attractive research area in the field of broadband light source design for utilizing it in various applications associated with nonlinear optics in recent years. In this work, the numerical demonstration of ultrabroadband supercontinuum generation in the mid-infrared region by using complementary metaloxide-semiconductor compatible Si-rich Silicon Nitride as core in a planar waveguide design employing two different cladding materials either of LiNbO 3 or MgF 2 glass as top and bottom, are explored. A rigorous numerical investigation of broadband source design in the mid-infrared using 2 mm long Si-rich Silicon Nitride Waveguides are studied in depth in terms of waveguide structural parameter variations, input peak power variation, unexpected deformation variation of the waveguide along the core region during fabrication, and spectral coherence analysis. Among the several waveguide models studied, two promising designs are identified for wideband supercontinuum generation up to the mid-infrared using very low input peak power of 50 W. Simulation results from the output of one of the proposed models reveal that the spectral coverage spanning from 0.8 µm to 4.6 µm can be obtained by the LiNbO 3 cladded waveguide and nearly a similar spectral coverage can be predicted by the other design, MgF 2 cladded waveguide. To the best of our knowledge, this can be the widest spectra spanning in the MIR region employing Si-rich Silicon Nitride Waveguide so far. In dispersion tuning as well as in supercontinuum generation, the effect of the occurrence of possible unexpected waveguide deformation around the core region during fabrication is studied. No significant amount of spectral changes of the proposed model for a maximum of 10 degrees inside/outside variation along the width are observed. However, even 1 degree up/down variation along the thickness could occur substantial spectral change at the waveguide output. Finally, the obtained output spectra from the proposed waveguides are found highly coherent and can be applied in various mid-infrared region applications such as optical coherence tomography, spectroscopic measurement, and frequency metrology.

Analysis and design of dispersion-engineered cascaded channel waveguide for mid-infrared supercontinuum generation employing pump source at telecommunication wavelength

“…The GNLSE is solved by our in-house developed MAT-LAB code following split-step Fourier method (SSFM) [21,30,46]. Since Si 3 N 4 has low Raman response [23], therefore, it is ignored during simulation by modifying the GNLSE equation as mentioned in [22]. The detailed simulation procedure, which is described in [21,23], are followed.…”

“…To address this problem, short length low cost planar waveguides can be a promising candidate as a counterpart in the SC source design. Modern well developed integrated waveguides fabrication facilities have accelerated the MIR SC generation in the integrated photonics platforms [19,20,21,22,23,24].…”