Optical interconnects using microLEDs
MicroLEDs may be used in providing intra-chip optical communications and/or inter-chip optical communications, for example within a multi-chip module or semiconductor package containing multiple integrated circuit semiconductor chips. In some embodiments the integrated circuit semiconductor chips may be distributed across different shelves in a rack. The optical interconnections may make use of optical couplings, for example in the form of lens(es) and/or mirrors. In some embodiments arrays of microLEDs and arrays of photodetectors are used in providing parallel links, which in some embodiments are duplex links.
1. An inter- or intra-chip optical communication system, comprising:
a waveguide having a waveguide core longitudinally bounded by waveguide cladding between a first endface and a second endface of the waveguide;
a first silicon photodetector monolithically integrated with a first integrated circuit chip, the first silicon photodetector being optically coupled to the first endface of the waveguide;
a first microLED made from gallium nitride and having one or more indium gallium nitride quantum wells, the first microLED being on a portion of the first silicon photodetector, and the first microLED electrically coupled to and on a portion of the first integrated circuit chip and optically coupled to the first endface of the waveguide, with an area of the first microLED being smaller compared to an area of the first silicon photodetector;
a second silicon photodetector monolithically integrated with a second integrated circuit chip, the second silicon photodetector being optically coupled to the second endface of the waveguide; and
a second microLED made from gallium nitride and having one or more indium gallium nitride quantum wells, the second microLED being on a portion of the second silicon photodetector, and the second microLED electrically coupled to and on a portion of the second integrated circuit chip and optically coupled to the second endface of the waveguide, with an area of the second microLED being smaller compared to an area of the second silicon photodetector.
2. The system of claim 1 , wherein the first integrated circuit chip, the second integrated circuit chip, the first silicon photodetector, the first microLED, the second silicon photodetector, and the second microLED are all within a same semiconductor package.
3. The system of claim 2 , wherein the first integrated circuit chip and the second integrated circuit chip are on a same substrate.
4. The system of claim 1 , wherein the first integrated circuit chip, the first silicon photodetector, and the first microLED are in a first package, and the second integrated circuit chip, the second silicon photodetector, and the second microLED are in a second package.
5. The system of claim 1 , wherein the first integrated circuit chip, the first silicon photodetector, and the first microLED are on a first shelf of a rack, and the second integrated circuit chip, the second silicon photodetector, and the second microLED are on a second shelf of a rack.
6. The system of claim 1 , wherein the waveguide comprises a multimode waveguide.
7. The system of claim 1 , wherein the first and second microLEDs are configured to emit light with a wavelength less than 500 nm.
8. The system of claim 1 , wherein the first silicon photodetector and the first microLED are optically coupled to the waveguide by an optical coupling assembly.
9. The system of claim 1 , wherein the first silicon photodetector and the first microLED are optically coupled to the waveguide by lenses and a turning mirror.
10. The system of claim 1 , wherein the area of the first microLED is 11% or less than the area of the first silicon photodetector, and wherein the area of the second microLED is 11% or less than the area of the second silicon photodetector.
11. The system of claim 1 , wherein the area of the first microLED and the area of the first silicon photodetector is such that, for light uniformly distributed across the first silicon photodetector, a loss of 0.5 dB or less will result due to presence of the first microLED, and wherein the area of the second microLED and the area of the second silicon photodetector is such that, for light uniformly distributed across the second silicon photodetector, a loss of 0.5 dB or less will result due to presence of the second microLED.