Optical phased array beam steering in the mid-infrared on an InP-based platform
Jason Midkiff, Kyoung Min Yoo, Jong‐Dug Shin, Hamed Dalir, Mohammad Hosain Teimourpour, Ray T. Chen
Abstract
Compact, lightweight, high-power beam-steering devices operating in the mid-infrared atmospheric window <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>3</mml:mn> <mml:mspace width="negativethinmathspace"/> <mml:mo>−</mml:mo> <mml:mspace width="negativethinmathspace"/> <mml:mn>5</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mtext>µ</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>4.6</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mtext>µ</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> , 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>2.5</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mi>λ</mml:mi> </mml:math> , we steer the beam to the maximum uninfringed field of view at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mo>±</mml:mo> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>11.5</mml:mn> </mml:mrow> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> .