Mid-IR supercontinuum generated in low-dispersion Ge-on-Si waveguides pumped by sub-ps pulses

Area of Science:

• Photonics
• Materials Science
• Integrated Optics

Background:

• Germanium-on-Silicon (Ge-on-Si) is a promising material for on-chip mid-infrared (mid-IR) broadband sources.
• Its wide transparency window, high Kerr nonlinearity, and CMOS compatibility make it attractive for integrated photonic devices.

Purpose of the Study:

• To present a low-loss Ge-on-Si waveguide.
• To achieve flat and low dispersion across a broad mid-IR spectrum (3-11 µm).
• To generate a coherent supercontinuum spanning from 2 to 12 µm.

Main Methods:

• Fabrication of a low-loss Ge-on-Si waveguide.
• Characterization of waveguide dispersion properties from 3 to 11 µm.
• Generation of supercontinuum using a sub-picosecond pulsed pump.

Main Results:

• A Ge-on-Si waveguide with flat and low dispersion was achieved between 3 and 11 µm.
• A coherent supercontinuum extending from 2 to 12 µm was generated.
• The supercontinuum generation required 700-fs pump pulses at a low peak power of 400 W in a 5.35 mm waveguide.

Conclusions:

• Ge-on-Si waveguides offer a viable platform for on-chip mid-IR broadband sources.
• The demonstrated device enables efficient supercontinuum generation with low pump power.
• This technology paves the way for compact and versatile mid-IR light sources.