One chip corresponds to one optical module

One optical chip does not correspond to one optical module; an optical module is a system that integrates multiple optical chips, electrical chips, and passive components.

Optical Module Structure

An optical module is an optoelectronic device used in fiber-optic communication to convert electrical signals into optical signals and vice versa. It typically includes: Optical chips: such as laser transmitters, photodetectors, or photonic integrated circuits (PICs)Electrical chips: driver circuits, amplifiers, and control electronicsPassive components: lenses, waveguides, and connectors The module functions as a complete system to handle signal transmission and reception, rather than being a single-chip device.

Number of Optical Chips

The number of optical chips in a module depends on the data rate and technology: Low-speed modules: usually 1–3 optical chips, often using discrete components and directly modulated lasers (DML)100G modules with PAM4 modulation: typically 2–5 optical chips, often arranged in arrays for parallel transmission400G modules: 4–10 optical chips, with silicon photonics PICs integrating multiple functions800G modules: 8–15 optical chips, often combining 1 PIC with 3–6 external optical chips Even when a single PIC is used, it internally integrates multiple optical functional units, so it still represents several optical chips in terms of functionality.

Photonic Integrated Circuits (PICs)A PIC is a microchip that integrates multiple photonic components, such as lasers, modulators, and detectors, onto a single substrate. While it can reduce the number of discrete chips in a module, it does not equate to a one-chip-per-module rule, because the PIC itself contains multiple optical functions.

Conclusion

In summary, an optical module is a multi-chip system, and the statement "one chip corresponds to one optical module" is incorrect. The number of optical chips varies with module complexity, data rate, and integration technology, and modern modules often use PICs to consolidate multiple optical functions into a single chip while still performing the roles of several optical chips.