Widely Tunable Mid-Wave Infrared Surface Emitting Lasers for Wide Angle Beam Steering
Navy SBIR FY2015.1


Sol No.: Navy SBIR FY2015.1
Topic No.: N151-023
Topic Title: Widely Tunable Mid-Wave Infrared Surface Emitting Lasers for Wide Angle Beam Steering
Proposal No.: N151-023-0739
Firm: Omega Optics, Inc.
8500 Shoal Creek Blvd.
Bldg. 4, Suite 200
Austin, Texas 78757
Contact: Swapnajit Chakravarty
Phone: (512) 996-8833
Abstract: This Small Business Innovation Research Phase I project aims at monolithically integrating high power edge emitting continuous wave (cw) quantum cascade lasers (QCLs) with waveguides and surface emitting sub-wavelength gratings in silicon-on-sapphire (SoS) enabling 70 percent surface emission of emitted QCL light and narrow beam wide angle 55 degrees by 20 degrees two-dimensional (2D) beam steering between 4-5micron wavelength range. Conventional surface emission with second order metallized gratings, photonic crystal gratings, buried gratings, and ring cavities have complexities in design and fabrication that need to be overcome to achieve high cw surface emission. Furthermore, wide angle 2D beam steering needs minimum element spacing of the order of wavelength which will be challenging to achieve when combined simultaneously with high power requirement. In our method, an edge emitting QCL is bonded to a SoS wafer. High intensity cw emission from demonstrated cw edge-emitting QCLs is completely evanescently coupled to demonstrated silicon waveguides in SoS and emitted from the surface using demonstrated mid-infrared sub-wavelength gratings in SoS. 2D wide angle beam steering can be achieved by wavelength tuning the multiple evanescently coupled DFB QCLs to silicon integrated waveguides, and phase shifting via thermal tuning, as demonstrated.
Benefits: This program seeks to develop a low-cost surface emitting QCL between 4-5 micron wavelength range via monolithic integration with sub-wavelength gratings in SoS substrates. QCLs have been demonstrated from the mid- to far-infrared wavelengths. The generalized approach with demonstrated cw edge emitting QCLs and passive integrated photonic components makes the proposed strategy suitable over the entire wavelength range from 3 to 14 micron with suitable choice of passive waveguiding semiconductor material. Wide angle 2D beam steering is made feasible by the small wavelength scale spacing between surface emitters, easily achievable with passive photonic components on-chip. The obvious application is in 2D beam steering in a multi-billion dollar optical phased array (OPA) market. OPAs in mid- and far-infrared make possible simple, affordable, and lightweight laser beam steering with very precise stabilization, random access pointing, and programmable multiple simultaneous beams. In applications such as LADAR/LIDAR, free-space optical wireless communication, inter-satellites links (LASERCOM), mid- and far-infrared OPAs can enable a low volume, narrow beam steering device in the atmospheric transmission windows, with the ability to quickly reconfigure the scan direction with good resolution and precision. New imaging and analysis paradigms are envisioned in optical microscopy for chemical and biological field and lab applications.

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