An optical neural network is constructed based on photonic integrated circuits to perform neuromorphic computing. In the optical neural network, matrix multiplication is implemented using one or more optical interference units, which can apply an arbitrary weighting matrix multiplication to an array of input optical signals. Nonlinear activation is realized by an optical nonlinearity unit, which can be based on nonlinear optical effects, such as saturable absorption. These calculations are implemented optically, thereby resulting in high calculation speeds and low power consumption in the optical neural network.

An optically computed optical coherence tomography (OC-OCT) technology is disclosed. The OC-OCT system performs depth resolved imaging by computing the Fourier transform of the interferometric spectra optically. The OC-OCT system modulates the interferometric spectra with Fourier basis function projected to a spatial light modulator and detects the modulated signal without spectral discrimination. The optical computation strategy enables volumetric OCT imaging without performing mechanical scanning and without the need for Fourier transform in a computer. OC-OCT performs Fourier transform signal processing optically, without the need of mechanical scanning, and before data acquisition unlike traditional OCT methods and systems. The scan-less OCT imaging is achieved through the use of spatial light modulator (SLM) that precisely manipulates light wave to generate output with desired amplitude and phase.

An optical neural network is constructed based on photonic integrated circuits to perform neuromorphic computing. In the optical neural network, matrix multiplication is implemented using one or more optical interference units, which can apply an arbitrary weighting matrix multiplication to an array of input optical signals. Nonlinear activation is realized by an optical nonlinearity unit, which can be based on nonlinear optical effects, such as saturable absorption. These calculations are implemented optically, thereby resulting in high calculation speeds and low power consumption in the optical neural network.

The present invention provides optical computing by means of fast Fourier transform Integration on Silicon On Insulator chip technology with implementation in the analog and temporal domain. This is done by cascading (N2) stages of delayed interferometers (couplers and phase shifters) where a parallel set of N time samples are taken and using the delay lines and phase of the optical components (constructive/deconstructive interference) the DFT is computed. The Optical Fast Fourier Transform (OFFT) design was built on passive components (22 couplers: cascaded Mach Zehnder Interferometer) used for addition and subtraction through optical interference, waveguides with short path differences are used for phase shifting and waveguides with long path differences are used for signal delay based on the needed number of outputs. Since the OFFT is a system of imbalanced interferometers, there are additional bends designed to compensate for the difference in power ratios of the arms.

A method of performing a complex Fourier transform of an input function including amplitude and phase information, including decomposing the input function into a plurality of sub-functions, wherein the Fourier transform of each sub-function includes an amplitude function and a phase function in which the phase is constrained to a plurality of possible phase values. The phase function of the Fourier transform of each sub-function is determined with an optical system that measures the amplitude function of an optical Fourier transform of the sub-function and changes in the amplitude function of the optical Fourier transform caused by applying a perturbation function to the sub-function. The determined phase functions and the measured amplitude functions are combined for each of the sub-functions to form the complex Fourier transform of the input function.

An optical processing system comprises an optical input; one or more spatial light modulator arrays; and a detector array; wherein at least of said spatial light modulator arrays incorporates a plurality of data elements focusing elements; said data elements and/or said focussing elements having multiple degrees of freedom.

An optical processing system comprises an optical input; one or more spatial light modulator arrays; and a detector array; wherein at least of said spatial light modulator arrays incorporates a plurality of data elements focusing elements; said data elements and/or said focussing elements having multiple degrees of freedom.

A wideband device for measuring the cross-correlation of a first signal and a second signal, includes a first frequency-shifting optical cavity comprising a first frequency shifter designed to shift the optical frequency of the first signal by a first frequency f1 per round trip in the first cavity, the first cavity having a first trip time 1; a second frequency-shifting optical cavity comprising a second frequency shifter designed to shift the optical frequency of the second signal by a second frequency f2 per round trip in the second cavity, the second cavity having a second trip time 2; the first and the second optical cavity being designed such that a maximum number of round trips of the first and the second signal in the first and the second cavity is equal to predetermined N, a detector designed to coherently detect the first signal transmitted by the first cavity and the second signal transmitted by the second cavity and generate a photocurrent (Tr) proportional to a luminous intensity detected by the detector, a low-pass filter designed to filter frequencies of the photocurrent that are lower than min (I), a processor configured to compute a Fourier transform of the photocurrent, so as to generate an output signal that is representative (II).