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A thermally activated variable attenuator for long-range (low-loss) surface plasmon-polariton (LRSPP) waves is discussed in this paper. The surface plasmon waveguide consists of a thin Au stripe on a thick layer of SiO2, which is covered by a thick layer of index-matched polymer. The structure is optically symmetric near room temperature, supporting an LRSPP. Increased attenuation of the mode occurs upon heating of the Au stripe via the passage of current therein. Heating substantially changes the refractive index of the polymer near the stripe, rendering the structure highly optically asymmetric and cutting off the mode. Thermal modeling results that link the injected current density to the refractive-index perturbation are presented and discussed. Experimental results validate the thermal modeling and demonstrate the operation of the device at a free-space optical wavelength near 1550 nm. The resistivity of the stripe is also measured as a function of the drive current, and the simultaneous use of the stripe as a thermal monitor is discussed and demonstrated [ABSTRACT FROM PUBLISHER]

GaAs traveling-wave electrooptic modulators based on the planar microstrip structure (PMS) have been thoroughly characterized theoretically and a near-optimal design is proposed. The optical, microwave, and modulator performance are investigated in detail. The structure is simple to fabricate and so should provide cost advantages. An electrical 3-dB bandwidth of about 15 GHz (optical 3-dB bandwidth of about 40 GHz) is obtained for our best design. [ABSTRACT FROM PUBLISHER]

GaAs traveling-wave electrooptic (EO) modulators based on capacitively loaded coplanar strips (CPSs) have been extensively modeled, and near-optimal designs are presented. The modulator operates in a push-pull mode, and the electrodes are coupled capacitively in series via the doped under layer. The best design reported herein has asymmetric CPSs 2 cm long and generated a figure of merit of about 9.36 GHz/V. This figure of merit is an improvement by a factor of about 2.5 over the best design reported to date for this modulator architecture. Modulator bandwidths in the range of 40-70 GHz (3 dB electrical) are predicted for various designs; the corresponding optical bandwidths are in the range of 75-110 GHz (3 dB optical). [ABSTRACT FROM PUBLISHER]