Thermo-optic plasmo-photonic mode interference switches based on dielectric loaded waveguides

Abstract

We demonstrate an efficient thermo-optic dielectric loaded surface plasmon polariton waveguide (DLSPPW) 2 × 2 switch using a high thermo-optic coefficient polymer and a dual mode interference configuration. Unlike previous configurations relying on single-mode waveguide circuitry, the switch we consider is based on the interference between a plasmonic and a low-damping photonic mode of the DLSPPW, thus leading to the minimization of insertion losses of the device. Switching extinction ratios of 7 dB are measured for a compact 119 μm-long device. The overall device performances are in good agreement with numerical simulations performed using the beam propagation method.

Merging Plasmonics and Silicon Photonics Towards Greener and Faster “Network-on-Chip” Solutions for Data Centers and High-Performance Computing Systems

“…The principle of operation regarding the TO switching is the following: In the 500×600 nm 2 PMMA ridge, the DLSPP mode fills practically the whole ridge, while the largest fraction of the mode is concentrated at the metal-dielectric interface. The strong confinement at the metal-dielectric interface renders the mode very sensitive to any temperature variation induced through current injection in the metal; in this way the underlying gold film acts as a heating electrode for the dielectric ridge, modifying in a very efficient way the DLSPP mode effective index via changing the PMMA refractive index [32]- [34], [52] and requiring only a small amount of consumed power. At the same time, the inherent instantaneous heating of the metal is immediately transferred to the propagating SPP mode, again due to its strong confinement at the metal-dielectric interface, leading to small response times of the TO effect in the DLSPP waveguide.…”

“…Another approach for bringing down the consumed power is the utilization of polymer materials with higher TOC value instead of PMMA loadings. For example, Cycloaliphatic acrylate (Cyclomer) exhibits almost three times higher TOC than PMMA and has been already successfully applied as the polymer loading in DLSPP switching structures [34], [38]. Though yet not optimized for lowenergy switching operation, this route is expected to significantly decrease the required energy levels without compromising the switching performance.…”

“…These dimensions ensure the existence of a single TM mode inside the polymer at telecom wavelengths, both for the nominal and the widened DLSPP waveguides, as depicted in Figure 7 Taking advantage of the default π/2 phase asymmetry introduced at the lower plasmonic branch, this asymmetric interferometric configuration is capable of performing switching with only a π/2 phase shift compared to all-plasmonic symmetric MZI switches [52]- [54]. The injection of electric current to a MZI arm yields a temperature rise that alters the effective index of the mode propagating on the heated arm, leading to a phase shift via this TO effect [32], [34], [52]. By electrically controlling the upper A-MZI arm, a negative phase shift is experienced by the propagating DLSPP waveguide mode as a result of the PMMA's TOC.…”

“…Regarding the TO effect, the underlying metallic layer, which is in direct contact with the polymer and therefore with the largest part of the DLSPP mode field, serves as an energyefficient electrode that yields immediate change of the effective index of the propagating mode at the presence of electric current, leading to fast TO responses. These advantages render the DLSPP waveguides ideal for TO manipulation of the plasmonic waves in various functional circuitry implementations like modulation [32], [33], ON/OFF gating [25] and switching [34], [35]. The progress made so far on active DLSPP-based circuits renders the TO effect as the most mature mechanism for bringing low-energy active plasmonics in true data traffic environments [25], [31].…”

Indium-Tin-Oxide for High-performance Electro-optic Modulation

“…electro-optic polymers), and fatigue and solvent sensitivity. Although polymer-based thermo-optic modulators (and switches) have several drawbacks such as significant power consumption, slow transition time (usually > 1 µs), the mechanism shows operational devices and sub-systems onchip [34,35]. Phase transition and thermal-optic effect based modulators can provide significant response, however the time frame is high and allows for an operation speed on the order of MHz [36].…”