Molecular Fingerprint Sensing Using Ge-on-Si Waveguides

Germanium-on-silicon, mid-infrared waveguides are used to demonstrate molecular fingerprint sensing of poly(methyl methacrylate) between 7.5 and 10 μm wavelength. The results are compared to Fourier transform infrared spectroscopy measurements, highlighting the potential of the platform for the identification of analytes

Ge-on-Si Mid-Infrared Waveguides Operating up to 11 μm Wavelength

Germanium-on-silicon, mid-infrared waveguides operating up to 11 micron wavelength are demonstrated for the first time, with propagation losses below 5.5 dB/cm. The results indicate that the platform could be suitable for sensing applications in the 8–13 micron atmospheric window of the molecular fingerprint region

Ultra-broadband mid-infrared Ge-on-Si waveguide polarization rotator

The design, modeling, micro-fabrication, and characterization of an ultra-broadband Ge-on-Si waveguide polarization rotator are presented. The polarization rotator is based on the mode evolution approach where adiabatic symmetric and anti-symmetric tapers are utilized to convert from the fundamental transverse magnetic to electric mode. The device is shown to be extremely fabrication tolerant and simple to fabricate. The fabricated devices demonstrate a polarization extinction ratio of ≥15 dB over a 2 μm bandwidth (9-11 μm wavelength) with an average insertion loss of <1 dB, which is an order of magnitude improvement compared to previously demonstrated devices. This device will provide polarization flexibility when integrating quantum cascade lasers on-chip for mid-infrared waveguide molecular spectroscopy