High-capacity communications satellite using passive optical beamforming

A method for broadcasting a radio-frequency beam from a satellite in orbit, comprising:

• (a) uplinking a wavelength-division multiplexed composite optical signal comprising optical carrier signals of different wavelengths from a ground station to a telescope onboard the satellite, wherein each optical carrier signal is modulated to carry a respective set of data;
• (b) demultiplexing the wavelength-division multiplexed composite optical signal to form a multiplicity of optical signals having different wavelengths;
• (c) using respective binary tree-based optical beamforming networks comprising optical ring resonators configured with preset time delays for time delaying the multiplicity of optical signals having different wavelengths;
• (d) converting the time-delayed optical signals output by the binary tree-based optical beamforming networks into electrical signals;
• and
• (e) transmitting a radio-frequency beam containing the respective sets of data at a steering angle in response to receipt of the electrical signals by a transmit antenna array, the steering angle being a function of the preset time delays in the binary tree-based optical beamforming networks.

A method for broadcasting a radio-frequency beam from a satellite in orbit, comprising:

• (a) uplinking a wavelength-division multiplexed composite optical signal comprising optical carrier signals of different wavelengths from a ground station to a telescope onboard the satellite, wherein each optical carrier signal is modulated to carry a respective set of data;
• (b) demultiplexing the wavelength-division multiplexed composite optical signal to form a multiplicity of optical signals having different wavelengths;
• (c) using passive optical beamforming networks configured with preset time delays for time delaying the multiplicity of optical signals having different wavelengths;
• (d) multiplexing the multiplicity of time-delayed optical signals having different wavelengths using a multiplicity of multiplexers to form composite optical beams that have the respective time delays;
• (e) converting the time-delayed composite optical beams into electrical signals;
• and
• (f) transmitting a radio-frequency beam containing the respective sets of data at a steering angle in response to receipt of the electrical signals by a transmit antenna array, the steering angle being a function of the preset time delays in the passive optical beamforming networks.

A method for broadcasting a radio-frequency beam from a satellite in orbit, comprising:

• uplinking a wavelength-division multiplexed composite optical signal to the satellite, the components of the wavelength-division multiplexed optical beam comprising respective optical carrier signals having different wavelengths which are modulated to carry data;
• demultiplexing the wavelength-division multiplexed composite optical signal to form a multiplicity of optical signals having different wavelengths;
• time delaying the multiplicity of optical signals having different wavelengths using respective binary tree-based optical beamforming networks comprising optical ring resonators configured with time delays and optical splitters optically coupled by waveguides;
• converting the time-delayed optical signals into electrical signals;
• and
• transmitting radio-frequency signals at a steering angle in response to receipt of the electrical signals by a transmit antenna array, the steering angle being a function of the time delays, the radio-frequency signals being modulated to carry the data contained in the wavelength-division multiplexed optical beam.

A communications satellite system comprising:

• an optical gateway configured to transmit a wavelength-division multiplexed optical beam, the components of the wavelength-division multiplexed optical beam comprising respective optical carrier signals having different wavelengths which are modulated to carry data;
• a receive antenna configured to receive radio-frequency signals;
• and
• a communications satellite in orbit, wherein the communications satellite comprises:
• a telescope configured to receive the wavelength-division multiplexed optical beam from the optical gateway;
• a multiplicity of optical beamforming networks optically coupled to the telescope, each optical beamforming network being a respective binary tree-based optical beamforming network comprising optical ring resonators and optical splitters optically coupled by waveguides and configured to split modulated optical carrier signals carrying data which pass through the telescope into a multiplicity of optical signals, make time delay adjustments to those optical signals, and output time-delayed optical signals;
• a multiplicity of photonic sensors for converting the time-delayed optical signals output by the multiplicity of optical beamforming networks into electrical signals;
• and
• a transmit antenna array comprising a multiplicity of antenna elements electrically coupled to the photonic sensors and configured to convert the electrical signals from the photonic sensors into data-carrying radio-frequency signals which are broadcast in a direction which is a function of the time delay adjustments made by the multiplicity of optical beamforming networks,
• wherein the time delay adjustments are selected so that the broadcast data-carrying radio-frequency signals will be received by the receive antenna.