Ultrafast emulation of retinal neuronal circuits with artificial VCSEL optical neurons

Biological retinal neuronal circuits are emulated using a system of connected 1550 nm Vertical-Cavity Surface-Emitting Laser (VCSEL)-neurons. Spiking and non-spiking neuronal responses are reproduced at ultrafast speed (>7 orders of magnitude faster than neurons) with prospects for novel brain-inspired computing platforms and Artificial Intelligence

Neuromorphic photonics with laser dynamics

We report on the activation, inhibition and propagation of controllable neuron-like spiking signals at sub-nanosecond speeds (>7 orders of magnitude faster than neurons) in artificial optical neurons based upon Vertical-Cavity Surface-Emitting Lasers. These results offer great prospects for future ultrafast photon-enabled neuromorphic computing platforms

Automated precision alignment of optical components for hydroxide catalysis bonding

We describe an interferometric system that can measure the alignment and separation of a polished face of a optical component and an adjacent polished surface. Accuracies achieved are ∼ 1μrad for the relative angles in two orthogonal directions and ∼ 30μm in separation. We describe the use of this readout system to automate the process of hydroxide catalysis bonding of a fused-silica component to a fused-silica baseplate. The complete alignment and bonding sequence was typically achieved in a timescale of a few minutes, followed by an initial cure of 10 minutes. A series of bonds were performed using two fluids - a simple sodium hydroxide solution and a sodium hydroxide solution with some sodium silicate solution added. In each case we achieved final bonded component angular alignment within 10 μrad and position in the critical direction within 4 μm of the planned targets. The small movements of the component during the initial bonding and curing phases were monitored. The bonds made using the sodium silicate mixture achieved their final bonded alignment over a period of ∼ 15 hours. Bonds using the simple sodium hydroxide solution achieved their final alignment in a much shorter time of a few minutes. The automated system promises to speed the manufacture of precision-aligned assemblies using hydroxide catalysis bonding by more than an order of magnitude over the more manual approach used to build the optical interferometer at the heart of the recent ESA LISA Pathfinder technology demonstrator mission. This novel approach will be key to the time-efficient and low-risk manufacture of the complex optical systems needed for the forthcoming ESA spaceborne gravitational waves observatory mission, provisionally named LISA

Construction of rugged, ultrastable optical assemblies with optical component alignment at the few microradian level

A method for constructing quasimonolithic, precision-aligned optical assemblies is presented. Hydroxide-catalysis bonding is used, adapted to allow optimization of component fine alignment prior to the bond setting. We demonstrate the technique by bonding a fused silica mirror substrate to a fused silica baseplate. In-plane component placement at the submicrometer level is achieved, resulting in angular control of a reflected laser beam at the sub-10-μrad level. Within the context of the LISA Pathfinder mission, the technique has been demonstrated as suitable for use in space-flight applications. It is expected that there will also be applications in a wide range of areas where accuracy, stability, and strength of optical assemblies are important

Putting Towns on the Policy Map: Understanding Scottish Places (USP)

Studies of places have been dichotomised as rural or urban. Towns, however, are neither rural nor urban. Towns have been neglected in research and policy agendas. In England the recent focus has been on high streets whereas in Scotland it has been on places and towns. Understanding Scottish Places (USP) is a web based platform that has become a key tool for evidence gathering, town comparison, knowledge exchange, regeneration planning and informed decision making for Scottish towns. USP is novel and contemporary and is engaging new ways of looking at, and planning in, and for, towns. This paper places USP in the research context and considers its development and use

Electrically-controlled spiking regimes in vertical-cavity surface emitting lasers

Electrically-controlled, tuneable and repeatable neuron-like spiking regimes are generated in an optically-injected 1300 nm Vertical-Cavity Surface-Emitting Laser at sub-nanosecond speeds (>7 orders of magnitude faster than neurons). These results offer great prospects for compact and ultrafast photonic neuronal models for future neuromorphic computing platforms

Electrically-controlled neuron-like spiking regimes in vertical-cavity surface-emitting lasers at ultrafast rates

We report experimentally on the electrically-controlled, tunable and repeatable neuron-like spiking regimes generated in an optically-injected vertical-cavity surface-emitting laser (VCSEL) operating at the telecom wavelength of 1300 nm. These fast spiking dynamics (obtained at sub-nanosecond speed rates) demonstrate different behaviours observed in biological neurons such as thresholding, phasic and tonic spiking and spike rate and spike latency coding. The spiking regimes are activated in response to external stimuli (with controlled strengths and temporal duration) encoded in the bias current applied to a VCSEL subject to continuous wave (CW) optical injection (OI). These results reveal the prospect for fast (>7 orders of magnitude faster than neurons), novel, electrically-controlled spiking photonic modules for future neuromorphic computing platforms