Quantum Cascade Lasers: Giant Pulse Occurrences, Laser Responses to Modulation, Frequency Comb Dynamics

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Extreme Events in Quantum Cascade Lasers Enable an Optical Neuron System 10,000× Faster Than Biological Neurons

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Giant pulses, fine tuning.  The team’s optical neuron system demonstrates behaviors like those observed in biological neurons, such as thresholding, phasic spiking, and tonic spiking. Fine tuning of modulation and frequency allows control of time intervals between spikes. Grillot explains, “The neuromorphic system requires a strong, super-threshold stimulus for the system to fire a spiking response, whereas phasic and tonic spiking correspond to single or continuous spike firing following the arrival of a stimulus.” To replicate the various biological neuronal responses, interruption of regular successions of bursts corresponding to neuronal activity is also required.

Recently, extreme events have been observed in quantum cascade lasers, as reported by researchers from Télécom Paris (France) in collaboration with UC Los Angeles (USA) and TU Darmstad (Germany). The giant pulses that characterize these extreme events can contribute the sudden, sharp bursts necessary for communication in neuromorphic systems inspired by the brain’s powerful computational abilities. Based on a quantum cascade laser (QCL) emitting mid-infrared light, the researchers developed a basic optical neuron system operating 10,000× faster than biological neurons.

Quantum cascade laser.  Experimentally demonstrated for the first time in 1994, quantum cascade lasers were originally developed for use under cryogenic temperatures. Their development has advanced rapidly, allowing use at warmer temperatures, up to room temperature. Due to the large number of wavelengths they can achieve (from 3 to 300 microns), QCLs contribute to many industrial applications such as spectroscopy, optical countermeasures, and free-space communications.

+  According to Grillot, the physics involved in QCLs is totally different than that in diode lasers. “The advantage of quantum cascade lasers over diode lasers comes from the sub-picosecond electronic transitions among the conduction-band states (subbands) and a carrier lifetime much shorter than the photon lifetime,” says Grillot. He remarks that QCLs exhibit completely different light emission behaviors under optical feedback, including but not limited to giant pulse occurrences, laser responses to modulation, and frequency comb dynamics.

Source:  SPIE, INTERNATIONAL SOCIETY FOR OPTICS AND PHOTONICS (SciTechDaily).  SPIE, INTERNATIONAL SOCIETY FOR OPTICS AND PHOTONICS (SciTechDaily),  Extreme Events in Quantum Cascade Lasers Enable an Optical Neuron System 10,000× Faster Than Biological Neurons…

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