Proposal of on-chip ultrabroad supercontinuum generation ranging from visible to mid-infrared spectrum

Mid-infrared (MIR) supercontinuum generation (SCG) is essential for many MIR spectral applications. However, most MIR SCG methods require expensive, bulky, and difficult-to-integrate MIR femtosecond laser pumps. In this study, we propose an approach of MIR SCG with a C-band pump by introducing a cascade structure with uniform and chirped nanophotonic periodic-poling lithium niobate (PPLN) waveguides. Here the uniform PPLN is used for realizing SCG in the near-infrared (NIR), while the phase-matched difference frequency generation occurs in the chirped PPLN waveguide to convey the spectrum to MIR. The simulated result indicates a broad SCG ranging from visible (640 nm) to MIR (5.3 μm) is achieved under 1550 nm 50-fs pulses with a pulse energy of 50 pJ. The present on-chip MIR SCG with a C-band-pump is realistic and finds many potential applications in environmental monitoring, medical imaging, and sensing.