Mid-infrared GaAs/AlGaAs micro-ring resonators characterized via thermal tuning

Micro-ring resonators with a decoupling waveguide have been manufactured from GaAs/Al_0.2Ga_0.8As, accommodating mid-infrared wavelengths, and were characterized via thermal tuning. A Q-factor of 1900, a thermal full width at half maximum of 8 °C, and a thermal free spectral range of 18 °C have been achieved. The low Q-factor indicates comparatively high coupling efficiency from the input waveguide into the decoupling waveguide. The micro-ring resonators shown herein are suitable structures for advanced mid-infrared chem/bio sensing strategies via resonant-cavity enhancement. In addition, they offer high spectral resolution for evanescent field sensing strategies via effective wavelength de-multiplexing waveguide structures.