Mark Stansberry

Aiming to become the global leader in chip-scale photonic solutions by deploying Optical Interposer technology to enable the seamless integration of electronics and photonics for a broad range of vertical market applications

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Mark Stansberry

posted on Dec 18, 2023 11:52AM

https://www.linkedin.com/feed/update/urn:li:activity:7142395339197591553/

Light Based Computer Architecture ..The Dawn of the Nanophotonics Age ., Mark Stansberry .. Dec 17th, 2023

Light based computer architecture is in many ways similar to electronics based computer architecture. Even at that, you do need to establish an interface between electronics and photonic integrated circuits. That can be done with an optoelectronic interposer (OEI). The sketch below is based on POET Technologies' OEI. On the left hand side is a bank of Instruction Processing Units (IPUs) and Data Processing Units (DPUs). In the center is a bank of POET's OEI units. On the right hand side is a bank of High Bandwidth Memory (HBM) 3D memory stack units.

The IPU and DPU banks exchange electronic data and address information with the OEI units. The electronic data that the OEI units receive can be converted to light data that is transmitted down the light bus. The light data that is received can also be converted to electronic data and sent back to an IPU/DPU or HBM unit in the chains. Which IPU/DPU unit or which HBM unit electronic data is sent to depends whether or not that location is the best location for the processing in terms of data center efficiency.

The value OEI architecture is that it eliminates the need to convert data from the electronic domain to the light domain or vice versa if an intended memory node or processing node is not logistically optimal. In an all-electronic version of the architecture, an electronic switch fabrics would be used instead of the OEI based optoelectronic switch. In an all-electronics version, the most appropriate nodes to use would first be determined and the switch would be configured to make a connection between the selected IPU/DPU and HBM nodes. Then, the data would be transferred between the two units.

This becomes problematic if the only available IPU/DPU and HBM units are located far apart in the data center. The long distance would result in higher power dissipation, voltage transients, noise, thermal dissipation and latency times. With the OEI interposer design, data can be transferred long distances without the power, voltage transients, noise, thermal and latency associated with the electronic design, Power, noise, timing delays and transients are only at the connecting OEI, HBM and IPU/DPU units, where light is converted to electronic signals and electronic signals are converted to light signals. And these are much less than what would be incurred in total when electronic data has to make a long journey down metal wires and cables.

The value of an OEI design in a data center is often during peak times. In this situation large amounts of data can be transferred to far away underused IPU/DPU and HBM units without increasing the power and thermal cooling requirements of the data center, and more so, without the worry that voltage transients and noise would corrupt the data, which would require the data to be reprocessed and retransmiitted, aka a mini-crash.