Low-Loss Buried InGaAs/InP Integrated Waveguides in the Long-Wave Infrared.

In this work, we present a photonic integrated platform based on buried InGaAs waveguides with InP cladding that operates over a large mid-infrared (mid-IR) spectral range. Thanks to wet-etch fabrication patterning and Fe doping, low propagation losses below 1.2 dB/cm (0.3 cm -1 loss coefficient) have been obtained between 4.6 and 11.2 μm wavelengths (890-1960 cm -1 wavenumber), in both transverse electric (TE) and transverse magnetic (TM) polarization modes. The possibility of monolithically integrating such waveguides with mid-IR sources offers promising perspectives for developing broadband, homogeneously integrated systems.