Extreme polarization-dependent supercontinuum generation in an uncladded silicon nitride waveguide

Abstract

We experimentally demonstrate the generation of a short-wave infrared supercontinuum in an uncladded silicon nitride (Si3N4) waveguide with extreme polarization sensitivity at the pumping wavelength of 2.1 µm. The air-clad waveguide is specifically designed to yield anomalous dispersion regime for transverse electric (TE) mode excitation and all-normal-dispersion (ANDi) at near-infrared wavelengths for the transverse magnetic (TM) mode. Dispersion engineering of the polarization modes allows for switching via simple adjustment of the input polarization state from an octave-spanning soliton fission-driven supercontinuum with fine spectral structure to a flat and smooth ANDi supercontinuum dominated by a self-phase modulation mechanism (SPM). Such a polarization sensitive supercontinuum source offers versatile applications such as broadband on-chip sensing to pulse compression and few-cycle pulse generation. Our experimental results are in very good agreement with numerical simulations.

Supercontinuum in integrated photonics: generation, applications, challenges, and perspectives

“…Unlike the work on Si reviewed in the previous section which was restricted to exploiting anomalous dispersion waveguides, Si 3 N 4 also shows excellent performance in terms of ANDi SCG, a less studied approach in waveguides since a low and flat all-normal dispersion at telecom wavelengths is typically more challenging to achieve in integrated designs. In [ 80 ], ANDi SCG was demonstrated by engineering the dispersion of the polarization modes in an air-clad Si 3 N 4 waveguide ( Figure 10(c) ). The ANDi SC obtained from pumping the TM mode showed the expected smooth spectrum without the fine spectral structure or large dips that are seen when pumping the TE mode in the anomalous dispersion regime, a typical signature of SCG driven by soliton dynamics, as shown in Figure 10(d) .…”

Recent Progress of Supercontinuum Generation in Nanophotonic Waveguides

“…[287] Copyright 2020, Optica Publishing Group. b) Experimental SCG in Si 3 N 4 waveguide for TM mode as increasing incident peak power from E. Tagkoudid et al [288] Reproduced with permission. [288] Copyright 2021, Optica Publishing Group.…”

“…[ 288 ] Reproduced with permission. [ 288 ] Copyright 2021, Optica Publishing Group. c) Experimental SC spectra of different peak powers for the TE mode in the As 2 S 3 rib waveguide from M. R. E. Lamont et al.…”

“…b) Experimental SCG in Si 3 N 4 waveguide for TM mode as increasing incident peak power from E. Tagkoudid et al [288] Reproduced with permission. [288] Copyright 2021, Optica Publishing Group. c) Experimental SC spectra of different peak powers for the TE mode in the As 2 S 3 rib waveguide from M. R. E. Lamont et al [227] Reproduced with permission.…”

“…Tagkoudid et al demonstrated the extreme polarization‐sensitive dynamics of SCG experimentally, and the corresponding bandwidth of SC with all‐normal dispersion is 700 nm. [ 288 ] L. Zhang et al showed the simulated SCG based on Si 3 N 4 slot waveguide. [ 240 ] The obtained dispersion was normal at all wavelengths, and the SC was from 630 to 2650 nm at −30 dB, covering a two‐octave bandwidth.…”