We present a method of improving the spatial resolution of a single-photon counting light detection and ranging system using a sub-pixel micro-scanning approach. The time-correlated single-photon counting technique was used to measure photon time-of-flight from remote objects. The high-sensitivity and picosecond timing resolution of this approach allows for high-resolution depth and intensity information to be obtained from targets with very low average optical power levels. The system comprised a picosecond pulsed laser source operated at a wavelength of 1550 nm and a 32 × 32 InGaAs/InP single-photon avalanche diode detector array. The detector array was translated along two orthogonal axes in the image plane of the receive channel objective lens using two computer-controlled motorized translation stages. This allowed for sub-pixel scanning, resulting in a composite image of the scene with improved spatial resolution. This paper presents preliminary measurements of depth and intensity profiles taken at stand-off distances of approximately 2.5 meters in laboratory conditions using average optical power levels in the micro-watt regime. A standard test chart was used to evaluate the resolving power of the system for both standard and micro-scanned images to assess performance improvements in spatial resolution. Depth profiles of targets were also obtained to investigate improvements in resolving small details and the quality of target edges.
Photonic techniques emulating the brain’s powerful computational capabilities are attracting considerable research interest as these offer promise for ultrafast operation speeds. In this talk we will review our approaches for ultrafast photonic neuronal models based upon Semiconductor Lasers, the very same devices used to transmit internet data traffic over fiber-optic telecommunication networks. We will show that a wide range of neuronal computational features, including spike activation, spiking inhibition, bursting, etc., can be optically reproduced with these devices in a controllable and reproducible way at sub-nanosecond time scales (up to 9 orders of magnitude faster than the millisecond timescales of biological neurons). Moreover, all our results are obtained using off-the-shelf, inexpensive Vertical-Cavity Surface Emitting Lasers (VCSELs) emitting at 1310 nm and 1550 nm; hence making our approach fully compatible with current optical communication technologies. Further, we will also introduce our recent work demonstrating the successful communication of sub-nanosecond spiking signals between interconnected artificial VCSEL-based photonic neurons and the potential of these systems for the ultrafast emulation of basic cortical neuronal circuits. These early results offer great prospects for novel neuromorphic (brain-like) photonic networks for brain-inspired ultrafast information processing systems going beyond traditional digital computing platforms.