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Analyzing the propagation dynamics of a light beam of arbitrary linear input polarization in an electro-activated photorefractive soliton we are able to experimentally find the conditions that separate its linear polarization components, mapping them into spatially distinct regions at the crystal output. Extending experiments to the switching scheme based on two oppositely biased solitons, we are able to transform this spatial separation into a separation of two distinct guided modes. The result is a miniaturized electro-optic polarization separator.

We report a novel design of a compact wavelength add-drop multiplexer utilizing dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs). The DLSPPW-based configuration exploits routing properties of directional couplers and filtering abilities of Bragg gratings. We present practical realization of a 20-µm-long device operating at telecom wavelengths that can reroute optical signals separated by approximately 70 nm in the wavelength band. We characterize the performance of the fabricated structures using scanning near-field optical microscopy as well as leakage-radiation microscopy and support our findings with numerical simulations. Surface-plasmon circuitry1 numbers a large variety of waveguiding configurations, ranging from tightly confined and very lossy surface plasmon-polariton (SPP) modes in metal nanowires 2 and chains of nanospheres 3 to moderate and long-travelling plasmonic modes, such as channel plasmon polaritons 4 , dielectric-loaded SPP waveguide (DLSPPW) modes 5 , long-range SPPs 6 , and long-range DLSPPW modes 7 . Considering only propagation loss and confinement characteristics, there is a technology superior to plasmonics, viz., silicon photonics. However, metal stripes as an inherent part of plasmonic waveguides provide easy access to the external electrodes. Moreover, the fact that the SPP fields reach their maximum at the metaldielectric interface makes electro-and thermo-optic modulation substantially more energetically efficient than in the case of silicon photonics 8-10 , since controlling electrodes can be placed right in the center of the SPP mode.Among all plasmonic configurations, DLSPPWs are so far the only waveguides that have been exploited for realization of complex circuit elements 11,12 , active control 13 , and partial loss compensation using optical pumping 14,15 . Furthermore, a low-energy thermo-optical tuning and fast error-free 10-Gb/s transmission through DLSPPW-based components has been recently demonstrated 10 , paving the way towards practical telecom applications. Importantly, DLSPPWs are naturally compatible with industrial fabrication using large-scale ultraviolet (UV) lithography 11 . While a great deal of DLSPPW-based passive and active photonic components has already been demonstrated, the task of spatial separation of telecom channels at different wavelengths appeared to be rather challenging due to considerable propagation losses in DLSPPWs 5 . Thus, configurations based on waveguide ring or racetrack resonators that have to employ sufficiently long resonators to minimize bend losses feature typically low transmission levels 10 . In this work, we present a very compact design of a wavelength add-drop multiplexer (WADM) based on DLSPPWs, which exploits filtering abilities of Bragg gratings 11 and routing properties of directional couplers 12 . The proposed configuration involves thereby only straight (coupled) waveguides that should be long enough to facilitate efficient Bragg reflection and power transfer -the requirements that can, in principle, be me...