Abstract: A method of beamforming by which a signal is received by a crossbar array of phase change materials (PCM) operative to be modulated electronically to impart complex Cartesian weighting and to retain transmission parameters for future processing. A PCM crossbar array can receive a signal from carrier waves modulated by an array of antenna elements, and send a complex Cartesian weighed result to a baseband combiner. Alternatively, a PCM crossbar array can receive a signal from carrier waves modulated by a baseband precoder, and send a complex Cartesian weighed result to an array of antenna elements. Either of the baseband combiner and baseband precoder can be digital or optical. Implementations allow optically based beamforming with the retention of long-term stochastics in the PCM cells, and are therefore broadband, fast, and energy efficient, as channel state information is not required to be stored otherwise.

Abstract: A photonic device configured to perform matrix vector multiplication operations at high frequencies is provided. The vector being multiplied by the matrix is defined by vector components at specific wavelengths. The device includes a first waveguide and a second waveguide. A series of tunable microring resonators (MRRs) are coupled to the first waveguide and to a respective series of passive delay rings (PDRs), which are coupled to the second waveguide. Each MRR/PDR pair defines a tunable matrix component (tunable weight) for a respective wavelength component of the vector. A series of controllable delay elements (CDEs) such as all-pass filters are coupled to the first waveguide, upstream from the tunable MRRs. Any tuning dependent group delay caused by the MRR/PDR pairs can be compensated by controlling the CDEs such that each wavelength components has substantially a same delay as the other wavelength components.

Abstract: A waveguide is coupled at both ends to a microring (MRR) modulator in order to form a Mach-Zehnder interferometer out of the resulting unit. The coupled waveguide can be modulated independently from the MRR modulator itself with either an in-resonance photoconductive heater or a geometrically suitable PN junction. During modulation with an applied voltage to the coupler, an independent modulation can be applied to the MRR in order to compensate for wavelength shifting. Ideal lengths for the coupler are identified, as well as a spiral configuration to reduce the coupler's footprint on a photonic integrated circuit. The resulting device has reduced cross-talk between channels of a cascaded MRR system. A second coupler can be coupled to each MRR symmetrically so as to reduce insertion losses, allowing for an increased weight range at the drop and through ports.