Optical pulse-width modulation used in an optical-stimulation cochlear implant

An apparatus for optically stimulating neurons of a cochlea of a person to provide sound-perception auditory sensations for the person, the apparatus comprising:

• an audio sensor configured to sense an audio signal in real time;
• an audio processor configured to extract real time audio signal strength from the audio signal;
• an optical generator configured to output a plurality of pulsed light signals having a pulse repetition rate, a peak power, and a pulse width, the plurality of pulsed light signals further having one or more successive pulses, each capable of stimulating a nerve action potential (NAP) in the neuron of the person;
• an optical guide configured to deliver the plurality of light signals to a plurality of locations in the cochlea of the person;
• and
• a controller configured to control the plurality of light signals output by the optical generator to optically stimulate one or more neurons in the cochlea in order to trigger NAPs in the one or more neurons of the cochlea, wherein the controller is further configured to hold constant the pulse repetition rate and the peak power of the plurality of pulsed light signals and, concurrently, to modulate the pulse width of the plurality of pulsed light signals in response to the real time audio signal strength so as to encode a dynamic range of sound loudness for the person in real time.