Haffner, C., Heni, W., Fedoryshyn, Y. et al. All-plasmonic Mach–Zehnder modulator enabling optical high-speed communication at the microscale. Nature Photon 9, 525–528 (2015). https://doi.org/10.1038/nphoton.2015.127
Optical modulators encode electrical signals to the optical domain and thus constitute a key element in high-capacity communication links1,2. Ideally, they should feature operation at the highest speed with the least power consumption on the smallest footprint, and at low cost3. Unfortunately, current technologies fall short of these criteria4. Recently, plasmonics has emerged as a solution offering compact and fast devices5,6,7. 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.