Figure 3.(a) EDFL output power versus diode pump current and (b) the EDFL optical spectrum.3.?Results and Discussion3.1. Synaptic Transfer FunctionBefore connecting the pre-synaptic neuron to the post-synaptic neuron, we measure a transfer function of the laser synapse. The transfer function is a frequency response of the synapse to an input signal. This important characteristic provides us with information about the frequency resolution of the synaptic sensor, i.e., its sensitivity to input frequency. Figure 4 shows the frequency resolution of the laser synapse (blue traces) and the post-synaptic neuron (red traces) to a harmonic signal applied to the laser pump current. The input frequency is indicated on the left-hand side of each time series.Figure 4.

Laser (blue traces) and post-synaptic neuron (red traces) responses to harmonic modulation at (a) low, (b) middle and (c) high frequencies. The amplitude of the input signal applied to the laser pump current from a signal generator A = 1 V, and I = 125 …For very low input frequencies (Figure 4a), a train of the laser and post-synaptic neuron spikes emerges at every period of the input signal. Inside each train of pulses, the synapse and post-synaptic neuron respond at different frequencies, and the number of spikes in the train decreases as the input frequency is increased. At higher frequencies (Figure 4b), it can happen that the post-synaptic neuron either stays silent (for f = 23.6 kHz), or there is a spike train (for f = 20.5 kHz and / = 27 kHz) regime while the laser emits a pulse at every period of the input signal.

For high frequencies (Figure 4c), the response of the post-synaptic neuron to a chaotic laser input can be either periodic (for f = 30.4 kHz) or irregular (for f = 55.4 kHz). All these and other regimes can be distinguished in the bifurcation diagrams of the laser peak intensity and the post-synaptic neuron inter-spike-interval (ISI) shown, respectively, in Figure 5a,b.Figure 5.Bifurcation diagrams of (a) laser peak intensity and (b) post-synaptic neuron inter-spike-interval (ISI) using modulation frequency as a control parameter. A = 1 V, and I = 125 mA.While the bifurcation diagram of the laser peak intensity is the transfer function of the laser synaptic sensor, the ISI is the transfer function of the system formed by the laser and the post-synaptic neuron.

The diversity of dynamical regimes obtained in the laser and its high sensitivity to the input frequency indicate a high flexibility of the laser synapse that can be beneficial for controlling signal transmission from one neuron to the other.3.2. Neuron ConnectionWe now consider the artificial neuron system formed by pre- and p
In the electrochemical field, sensors are the primary devices used for data acquisition. If the sensor shows Batimastat performance degradation or fails, it will have a serious effect on the measurement or monitoring process. Tomchenko et al.