We report on the development of 850-nm high-speed VCSELs optimized for low-power data transmission at cryogenic
temperatures near 100 K. These VCSELs operate on the n=1 quantum well transition at cryogenic temperatures (near
100 K) and on the n=2 transition at room temperature (near 300 K) such that cryogenic cooling is not required for initial
testing of the optical interconnects at room temperature. Relative to previous work at 950 nm, the shorter 850-nm
wavelength of these VCSELs makes them compatible with high-speed receivers that employ GaAs photodiodes.
Proc. SPIE. 8014, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXII
KEYWORDS: Target detection, Staring arrays, Signal to noise ratio, Short wave infrared radiation, Imaging systems, Sensors, Interference (communication), Time metrology, Signal detection, Systems modeling
We investigate a dim-target-detection approach for pixellated focal-plane-arrays based on differential correlation
detection. The change in the temporal correlation of the output signals between an illuminated pixel and a dark reference
pixel is measured in real time over some number of samples and may enable more sensitive detection of dim targets
whose signal amplitudes are on the order of the noise levels of the sensor. If successful, target detection may be possible
with target signal-to-noise-ratios of less than 1 under practical conditions where dark drift may occur.
Fiber-optic sensors for sensing electrical current are attractive due to their inherent immunity to electromagnetic interference. Several groups have shown the use of Faraday rotation in magneto-optical materials as a function of current-induced magnetic field. In this work, fiber-optic sensors based on different mechanisms such as magnetic-fielddependent polarization coherence and power scattering effects in magneto-optical materials are demonstrated. These
novel sensor configurations can have advantages in that they exhibit power-independent or polarization-independent operation which can ultimately lead to fewer components and relaxed light source requirements compared to fiber-optic current sensor systems based on Faraday rotation.
This paper describes technologies developed at Sandia National Laboratories to support a joint DoD/DoE initiative to create a compact, robust, and affordable photonic proximity sensor for munitions fuzing. The proximity fuze employs high-power vertical-cavity surface-emitting laser (VCSEL) arrays, resonant-cavity photodetectors (RCPDs), and refractive micro-optics that are integrated within a microsensor whose volume is approximately 0.01 cm<sup>3</sup>. Successful development and integration of these custom photonic components should enable a g-hard photonic proximity fuze that replaces costly assemblies of discrete lasers, photodetectors, and bulk optics. Additional applications of this technology include void sensing, ladar and short-range 3-D imaging.
Monolithically-integrated optical gain-competition inverters are demonstrated at 1.55 μm in the InGaAsP/InP material system. The optical inverters consist of etched-facet slave lasers that are side-injected with tapered etchedfacet master lasers. Single-input optical inverters show improved quenching contrast for devices with larger taper width with respect to the slave laser length. Inverter performance also shows a dependence on the ridge width and lasing modes of the slave laser. Two-input optical inverters are characterized which demonstrate NAND and NOR logic operation at different slave laser currents.