  Nonlinear optical processing of ambient natural light is highly desired in
computational imaging and sensing applications. A strong optical nonlinear
response that can work under weak broadband incoherent light is essential for
this purpose. Here we introduce an optoelectronic nonlinear filter array that
can address this emerging need. By merging 2D transparent phototransistors
(TPTs) with liquid crystal (LC) modulators, we create an optoelectronic neuron
array that allows self-amplitude modulation of spatially incoherent light,
achieving a large nonlinear contrast over a broad spectrum at
orders-of-magnitude lower intensity than what is achievable in most optical
nonlinear materials. For a proof-of-concept demonstration, we fabricated a
10,000-pixel array of optoelectronic neurons, each serving as a nonlinear
filter, and experimentally demonstrated an intelligent imaging system that uses
the nonlinear response to instantly reduce input glares while retaining the
weaker-intensity objects within the field of view of a cellphone camera. This
intelligent glare-reduction capability is important for various imaging
applications, including autonomous driving, machine vision, and security
cameras. Beyond imaging and sensing, this optoelectronic neuron array, with its
rapid nonlinear modulation for processing incoherent broadband light, might
also find applications in optical computing, where nonlinear activation
functions that can work under ambient light conditions are highly sought.
