This page groups material roles that already appear in public documents. A role can be absent or swapped in a given assembly, so the columns are not a list to be purchased together.
01
Semiconductors and sourcesSilicon photonic circuits, germanium detection, lasers. A design usually takes one source path.
02
Substrate and attachFirst-level substrate, redistribution, socket or solder. The NPO name sits on the socket side.
03
Fiber and exitSingle-mode or multimode; pigtail or connector. Another connector adds loss.
Three material roles. A specific design usually uses only some of them.
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Silicon photonic circuits and germanium detection
The ELSFP implementation agreement, comparing temperature limits, groups silicon photonic circuit elements and germanium photodetectors with silicon die, and states that lasers have historically had a much lower reliable junction temperature. Silicon photonic wafers and germanium detection are material classes named in that public text.
What changes between designs The framework also discusses integrated lasers, external continuous-wave light, and VCSEL engines for short-reach multimode fiber. Silicon photonics is one path, not a required NPO substrate.
The framework says the source may be several lasers at several wavelengths, for FR-class applications, or one or more lasers at one wavelength, for DR, VR, and SR-class applications. In a silicon photonic engine the lasers may sit inside the engine or outside it, with continuous-wave light used together with modulators.
What changes between designs An external laser takes extra insertion loss and may need higher optical power to compensate; an integrated laser has fewer losses to overcome. That is a tradeoff in the document, not a fixed recipe. VCSEL plus multimode fiber is described as a possible lower-power option for short reach, not as the default.
The framework defines co-packaging as attaching optical or electrical communications devices on the same first-level substrate as the host ASIC. It then names another arrangement: a packaged ASIC (die plus ASIC substrate or redistribution layer) and an engine, attached to a common substrate with sockets so they can be fitted and removed during assembly and rework. The document calls that arrangement socketed near-package optics.
What changes between designs The same section also describes solder attach with a ball grid or copper pillars. A socket needs a retention mechanism and uses area, while allowing rework; solder can reach a higher density, with a different rework and yield cost when many engines are integrated. The document sets the two side by side and does not declare either one the only method outside NPO. The 2018 XSR project note also says multiple chips would sit on a common organic package substrate. That is a statement about that project, not a claim that every near-package build uses the same organic substrate.
Single-mode and multimode fiber, pigtail or connector
The framework says optical engines, like their pluggable counterparts, connect switches and servers over single-mode or multimode fiber. An engine can be pigtailed or built with a connector. The pigtail can be a high-density ribbon; if it is long enough, another connector to the front panel may be unnecessary.
What changes between designs An extra connector raises insertion loss relative to an equivalent front-panel pluggable. The document also says the high-density fiber connectors of the time, MPO among them, may not meet the size and density limits, and that a new connector technology may be required. That is a problem statement, not a connector design from NPOTEC.
If an engine is socketed on the co-packaged assembly, it needs mechanical compression. The usual sketch is bolts at the four corners of the socket; several sockets can share that hardware and trade a little overhead for density. One published reason for an external laser is to separate the laser’s thermal environment from the ASIC.
What changes between designs The framework’s application table lists air cooling and liquid cooling, and internal and external lasers, as parallel attributes. It does not assign one cell to near-package optics. ELSFP places a replaceable source at the faceplate for systems that choose an external laser. It is not a part in every assembly.