Group array photodetector combiner
High-performance ultra-wideband Phased Array Sensors (PAS) are disclosed, which have unique capabilities, enabled through photonic integrated circuits and novel optical architectures. Unique capabilities for a Receive PAS are provided by wafer scale photonic integration including heterogeneous integration of III-V materials and ultra-low-loss silicon nitride waveguides, combining key component technologies into complex PIC devices. Novel aspects include optical multiplexing combining wavelength division multiplexing and/or a novel extension to array photodetectors providing the capability to combine many RF photonic signals with very low loss. The architecture also includes optical down-conversion, as well as digital signal processing to improve the linearity of the system. Simultaneous multi-channel beamforming is achieved through optical power splitting of optical signals to create multiple exact replicas of the signals that are then processed independently.
1. A Group Array Photodetector Combiner (GAPC) device, comprising:
an array of N photodetectors, where N≥4, that receive a series of N optical signals, one optical signal to each of the N photodetectors;
wherein the array of N photodetectors forms a set of X groups of photodetectors, where X≥2; wherein each group of the set of X groups includes Y photodetectors directly electrically connected to each other, where Y≥2 and where N=X*Y;
wherein each group of the X groups of photodetectors is electrically connected to a next group of the X groups of photodetectors via an inductor, each said inductor having an inductance value L; and
wherein the inductance values L of each of the inductors are chosen to match a capacitance C of a corresponding group of the set of X groups of photodetectors to produce an artificial transmission line having an impedance Z, using the inductance values L within the artificial transmission line and inductance values L/2 at ends of the artificial transmission line, where Z=sqrt(L/C).
2. The device of claim 1 , wherein all of the N photodetectors are waveguide photodetectors having individual waveguide inputs.
3. The device of claim 1 , wherein an electrical output from the GAPC is the voltage across a load resistor at the end of the artificial transmission line.
4. The device of claim 1 , wherein each of the optical signals is comprised of multiple individual optical signals of different wavelengths, wherein there is an absence of any optical wavelength overlap between each of the multiple individual optical signals.
5. The device of claim 1 , wherein each of the array of N photodetectors is physically separate.
6. The device of claim 5 , wherein the optical signal input to each of the N photodetectors is comprised of multiple optical signals of different wavelengths, wherein there is an absence of any wavelength overlap between each of the multiple optical signals.
7. Two connected GAPC devices according to claim 1 , wherein each of said two GAPC devices are arranged as a differential pair through wiring.