Silicon photonics
Beginner
Making the parts that steer and switch light on silicon chips, using the same factories that make computer chips.
Novice
Building optical waveguides, modulators and detectors on silicon wafers with chip-making tools. Silicon does not emit light well, so the laser usually comes from a separate chip.
Expert
Waveguides, Mach-Zehnder or micro-ring modulators and germanium photodiodes in a CMOS-like process. Ring modulators are small and efficient but must be thermally tuned; MZMs are larger but more tolerant. Light is supplied by III-V lasers, integrated or external.