Dynamics of electron-trapping materials for use in optoelectronic neurocomputing

Optical realization of bioinspired spiking neurons in the electron trapping material thin film

A thin film of electron-trapping material (ETM), when combined with suitable optical bistability, is considered as a medium for optical implementation of bioinspired neural nets. The optical mechanism of ETM under blue light and near-infrared exposure has the inherent ability at the material level to mimic the crucial components of the stylized Hodgkin-Huxley model of biological neurons. Combining this unique property with the high-resolution capability of ETM, a dense network of bioinspired neurons can be realized in a thin film of this infrared stimulable storage phosphor. When combined with suitable optical bistability and optical interconnectivity, it has the potential of producing an artificial nonlinear excitable medium analog to cortical tissue.

Electron-trapping materials and electron-beam-addressed electron-trapping material devices: an improved model

An improved model governing the dynamics of electron-trapping materials (ETM's) under simultaneous illumination of blue and IR light is developed. The new model takes into account previously neglected effects, such as electron-trap-density saturation and dependence of electron-trapping efficiency on the existing level of trapped-electron density. Inclusion of both effects in a model is vitally important for effective use of ETM's in optoelectronic neurocomputing with pulsating neurons. Experimental verification of the new model is given. General issues of addressing ETM's with an electron beam are also studied, and a general design equation for electron-beam-addressed ETM devices is developed. In particular, two electron-beam-addressed ETM devices that are of special interest, the field-emission microcathode ETM spatial light modulator and the ETM-based image intensifier, are presented.

Optoelectronic neural dendritic tree processing with electron-trapping materials

We show that under simultaneous illumination of pulsed blue light and constant IR light the dynamic responses of electron-trapping materials could be employed to implement optically controlled neural dendritic responses. The importance of neurocomputing with biology-oriented spiking neurons and the role played by dendritic trees are discussed. Computer simulations of dendritic responses in biological neuron and experimental results of electron-trapping material dynamics are presented. These results show that electron-trapping materials are well suited for implementing optically controlled dendritic responses for use in large-scale biology-oriented optoelectronic spiking neural networks.

Pulsating neuron produced by electron-trapping materials

We report our results from the study of the dynamics of electron-trapping materials (ETM's) under simultaneous illumination of pulsed blue light and constant IR light. By combining the dynamic property of ETM with the S-shaped nonlinear I-V characteristic of a programmable unijunction transistor, we produce an optoelectronic pulsating neuron. A proof-of-concept experiment successfully produces oscillations and demonstrates the great potential of using ETM's to implement dense arrays of pulsating neurons.