Device for optically receiving a signal coming from a phased antenna array and associated antenna system
The invention relates to an optical reception device for receiving a signal from an antenna array comprising: a light source generating an optical carrier and M phased optical beams which are frequency-shifted relative to the optical carrier; a collection circuit comprising N paths connected to an antenna, and comprising a modulator of an incident signal; a beam-forming network connecting (M+1) first ports to N second ports connected to one path, M first ports being connected to the optical beams and a control port connected to the other ports so that a maximum optical intensity on the control port corresponds to phased signals on the N second ports.
1. An optical reception device, the optical reception device receiving a signal from a phased antenna array, the phased antenna array including N elementary antennas, each elementary antenna emitting a signal, each signal having a phase and an amplitude, N being an integer greater than 1, the reception device including:
a light source generating an optical carrier at a reference frequency and M phased optical beams relative to a replica of the optical carrier and which are frequency-shifted relative to the reference frequency, M being an integer greater than 1,
a collection circuit for the signals from the N elementary antennas, the collection circuit including N paths each connected to a respective elementary antenna, each path including a modulator modulating at least one of the phase and the amplitude of an incident signal according to a modulation,
a beam-forming network connecting M+1 first ports to N second ports, each second ports being connected to a respective path of the N paths, the M+1 first ports comprising:
M first ports being connected respectively to one of the M phased optical beams, and
a first port not connected to one of the M phased optical beams, the first port being a control port, the control port being connected to the M first ports so that a maximum optical intensity on the control port corresponds to phased signals on the N second ports,
a photodiode connected to the control port and measuring an optical intensity of a signal of the control port at the reference frequency, and
a controller controlling the modulation of each modulator as a function of the optical intensity measured by the photodiode.
2. The optical reception device according to claim 1 , wherein the collection circuit includes two additional paths in addition to the N paths, one of the additional paths being supplied by the optical carrier and the other path of the additional paths supplying the light source with a replica of the optical carrier.
3. The optical reception device according to claim 1 , wherein the controller controls the modulation of each modulator as a function of the optical intensity measured by the photodiode using a technique chosen from a group made up of a gradient descent algorithm, a Nelder-Mead algorithm, and a frequency marking technique.
4. The optical reception device according to claim 1 , wherein the beam-forming network is a Blass, or Butler, or Nolen matrix.
5. The optical reception device according to claim 1 , wherein the collection circuit includes multi-core fibers.
6. The optical reception device according to claim 1 , wherein each path of the collection circuit includes an optical filter eliminating a sideband.
7. The optical reception device according to claim 1 , wherein the light source includes two phase-locked lasers.
8. The optical reception device according to claim 1 , wherein the optical reception device includes a first part including the light source and the photodiode and a second part including the beam-forming network, the first part being made from Indium Phosphide (InP) and the second part being made from Silicon Nitride (SiN) or sub strate-on-insulator.
9. An antenna system including:
an optical reception device according to claim 1 , and
a phased antenna array, the phased antenna array including the N elementary antennas.
10. The antenna system according to claim 9 , the antenna system further including an optical emission device for controlling the phased antenna array, the emission device including:
a light source generating an optical carrier at a reference frequency and M phased optical beams relative to a replica of the optical carrier and which are frequency-shifted relative to the reference frequency, and
a beam-forming network connecting M first ports to the N second ports, each first port respectively being connected to one of the M optical beams generated by the light source and each second port generating a control signal of one of the N elementary antennas.
11. The antenna system according to claim 10 , wherein the light source of the emission device comprises two emission sub-sources each emitting a light wave with a first frequency gap, the light source of the reception device comprising two reception sub-sources each emitting a light wave with a second frequency gap, the first and the second frequency gaps being identical.