To keep pace with the demands in optical communications, electro-optic modulators should feature large bandwidths, operate across all telecommunication windows, offer a small footprint, and allow for CMOS-compatible fabrication to keep costs low(1). Here, we demonstrate a new ultra-compact plasmonic phase modulator based on the Pockels effect in a nonlinear polymer. The device has a length of only 29 mu m and operates at 40 Gbit s(-1). Its modulation frequency response is flat up to 65 GHz and beyond. The modulator has been tested to work across a 120-nm-wide wavelength range centred at 1,550 nm, and is expected to work beyond this range. Its operation has been verified for temperatures up to 85 degrees C and it is easy to fabricate. To the best of our knowledge, this is the most compact high-speed phase modulator demonstrated to date

Optical modulators encode electrical signals to the optical domain and thus constitute a key element in high-capacity communication links 1,2 . Ideally, they should feature operation at the highest speed with the least power consumption on the smallest footprint, and at low cost 3 . Unfortunately, current technologies fall short of these criteria 4 . Recently, plasmonics has emerged as a solution offering compact and fast devices 5-7 . Yet, practical implementations have turned out to be rather elusive.Here, we introduce a 70 GHz all-plasmonic Mach-Zehnder modulator that fits into a silicon waveguide of 10 μm length. This dramatic reduction in size by more than two orders of magnitude compared with photonic Mach-Zehnder modulators results in a low energy consumption of 25 fJ per bit up to the highest speeds. The technology suggests a cheap co-integration with electronics.Mach-Zehnder modulators (MZMs) are the most versatile electro-optical converters in high-end communication systems. MZMs are unique, as they can be used to encode multiple bits within one symbol with the highest quality. They are thus instrumental in increasing the capacity of modern communication links 1 . Until now, MZMs have mostly been based on the lithium niobate material system, which requires footprints on the order of cm 2 . Recently, more compact silicon-based modulators have emerged. These devices have already shown operation at bandwidths up to 55 GHz (ref. 8), they are cost-effective, and they feature lengths on the order of hundreds of micrometres to millimetres 2,3,8-12 . Yet, complementary metal-oxide semiconductor electronics (CMOS) house hundreds of transistors on a single μm 2 , making a co-integration of today's silicon MZMs with CMOS electronics impractical 4 . In pursuit of more compact silicon modulators, various approaches have been demonstrated, such as resonant silicon ring modulators 13,14 or germanium-based electro-absorption modulators 15,16 . However, encoding advanced modulation formats is challenging 17 , and high-capacity transmission has, so far, only been achieved with MZMs 2,12 . Instead, plasmonics has drawn significant interest as an alternative solution 6,7 . In plasmonics, optical signals are converted to surface plasmon polaritons (SPPs) propagating at metal-dielectric interfaces, where they can be confined below the diffraction limit of optics 18 . This means that plasmonic devices require only a few µm 2 of footprint 19,20 . With such reduced dimensions, the technology is much closer to bridging the size gap with respect to CMOS electronics. Furthermore, there are various theoretical studies indicating that plasmonic MZMs should offer hundreds of gigahertz of bandwidth 5,21 . To date, however, there is very little experimental evidence to support this claim. Recently, a plasmonic phase modulator demonstrated operation at 40 Gbit s −1 (ref. 22). One could now envision integrating such plasmonic phase modulators into a silicon waveguide MZM configuration. However, by combining plasmonics and silicon photoni...

This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.

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Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, neither silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonicorganic hybrid (POH) integration, which combine silicon-oninsulator (SOI) waveguides and plasmonic nanostructures with organic electro-optic cladding materials.