In-line extinction modulator based on long-range surface plasmon polaritons

We develop thermo-optic in-line extinction modulators (ILEMs) whose operation is based on the guiding of long-range surface plasmon polaritons (LRSPPs) along metal stripes embedded in polymer and heated by electrical signal currents. Several 1 cm long ILEMs, which utilize 15 nm thin and 8 μm wide gold stripes guiding LRSPPs and comprising 3-6 mm long control electrodes, are investigated at telecom wavelengths. The fabricated ILEMs feature low driving powers (∼100 mW) and high extinction ratios (∼30 dB) that depend weakly on the wavelength, moderate response times (∼0.5 ms) and the total (fiber-to-fiber) insertion loss of ∼8 dB when using single-mode fibers.