Optical phased array beam steering in the mid-infrared on an InP-based platform

Compact, lightweight, high-power beam-steering devices operating in the mid-infrared atmospheric window λ=3−5µm are attractive for aerial-based applications such as long-range lidar and countermeasures. In the near-infrared spectral region, optical phased arrays (OPAs) have emerged as the dominant nonmechanical on-chip beam-steering technology, with a preponderance in silicon-based platforms. Extensions to the mid-infrared spectral region are scarce. Further, considering that the requirements for high performance in this region will likely demand monolithic integration with quantum cascade lasers, development of the photonic technology on a native III–V platform is advantageous. To this end, at λ=4.6µm, on an InGaAs/InP platform, we experimentally demonstrate the operation of a 32-channel OPA with thermo-optic tuning for azimuthal (lateral) steering. With a waveguide spacing of 2.5λ, we steer the beam to the maximum uninfringed field of view at ±11.5∘.