Silicon optical modulators

  • A Corrigendum to this article was published on 01 September 2010

Abstract

Optical technology is poised to revolutionize short-reach interconnects. The leading candidate technology is silicon photonics, and the workhorse of such an interconnect is the optical modulator. Modulators have been improved dramatically in recent years, with a notable increase in bandwidth from the megahertz to the multigigahertz regime in just over half a decade. However, the demands of optical interconnects are significant, and many questions remain unanswered as to whether silicon can meet the required performance metrics. Minimizing metrics such as the device footprint and energy requirement per bit, while also maximizing bandwidth and modulation depth, is non-trivial. All of this must be achieved within an acceptable thermal tolerance and optical spectral width using CMOS-compatible fabrication processes. This Review discusses the techniques that have been (and will continue to be) used to implement silicon optical modulators, as well as providing an outlook for these devices and the candidate solutions of the future.

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Figure 1: Cross-sections of typical device structures implementing the three different mechanisms commonly used to electrically manipulate the free-carrier concentrations in plasma-dispersion-based silicon optical modulators.
Figure 2: The first devices to propose and realize modulation at gigahertz frequencies in silicon, together with the best present carrier-accumulation-type device.
Figure 3: Carrier-depletion-based silicon optical modulators, showing both the first proposed and present fastest devices.
Figure 4: The first silicon optical modulator to use a ring resonator structure to translate phase variations into intensity variations.
Figure 5: A possible future alternative to plasma-dispersion-based silicon optical modulators is the SiGe QCSE modulator.

Change history

  • 12 August 2010

    Ref. 86 was incorrectly cited in both the title and the last data row of Table 1. The correct citation is ref. 24, and this has been corrected for all versions of the article.

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Reed, G., Mashanovich, G., Gardes, F. et al. Silicon optical modulators. Nature Photon 4, 518–526 (2010). https://doi.org/10.1038/nphoton.2010.179

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