Abstract
Next‐generation inter‐chip communication requires ultrafast ultra‐compact interconnects. Designer plasmonics offers a possible route towards this goal. Further development of the plasmonic technique to circuit applications requires the direct amplification of plasmonic signals on a compact platform. However, significant signal distortions and limited operational speeds prevent the application of traditional MOS‐based amplifiers to plasmonics. Up to day, the amplification of surface plasmons without phase distortion has remained a scientific challenge. In this work, the concept of parametric amplification (PA) is transplanted to the plasmonics and is realized experimentally an ultrathin reconfigurable PA using a spoof surface plasmon polariton (SSPP) waveguide integrated with tunable and nonlinear varactors. The measured parametric gain in the experiment can reach up to 9.14 dB within a short nonlinear propagation length, for example, six SSPP wavelengths, in excellent agreement with the theoretical prediction. By tuning the bias voltage of varactors, the phase‐matching condition can be precisely controlled over a broad frequency band, enabling the authors to realize the multi‐frequency PA of plasmonic signals. Measured phase responses confirm that the plasmonic parametric amplifier can significantly suppress the signal distortions as compared with the traditional MOS‐based amplifier, which is a property highly desired for ultrafast wireless communication systems and integrated circuits.
Highlights
Next-generation inter-chip communication requires ultrafast ultra-compact of Tbps, but the inherent Abbe diffraction limit prevents high-density photonic device interconnects
Under the incident pump intensity of 1 × 105 W m−2 (correspondnonlinear propagation length (10λ). These results indicate that the Spoof surface plasmon polariton (SSPP) parametric amplification can realize a high gain in an ultra-compact device, opening up the possibilities for on-chip integration in the integrated circuits
In terms of the phase-matching condition of the second harmonic generation,[38,42] when nonlinear mixing occurs in a waveguide instead of a bulk medium, the phase-matching condition for three-wave mixing is possible to be satisfied by designing the dispersion characteristics of different SSPP modes in the waveguide
Summary
We investigate the key factors that will affect the parametric gain. Assuming that the light is propagating along the z-direction, i.e., Ep(z) = Ap(z)eikpz, Es(z) = As(z)eiksz, and Ei(z) = Ai(z)eikiz, corresponding to the electric fields at the pump, signal, and idler frequencies, respectively, where Ap, As, and Ai are the electric field amplitudes of the pump (ωp), signal (ωs), and idler (ωi) waves, respectively. The presence of finite dissipation losses always sets an ultimate limit of the maximum signal gain we can achieve To illustrate this point and demonstrate the unique properties of spoof surface plasom polaritons (SSPPs) in parametric amplification, we compare the signal gains of two different platforms (i.e., metal SPPs at visible, and SSPPs at microwave) using the theoretical model above. Since the optical SPPs (Au/Porous silicon) suffer from high Drude losses, the corresponding signal wave cannot be amplified unless the pump light intensity reaches as high as 3 × 1019 W m−2, which has to be generated by a femtosecond laser To circumvent this limitation, an SSPP parametric amplifier with small loss and high field confinement simultaneously is investigated. These results indicate that the SSPP parametric amplification can realize a high gain in an ultra-compact device, opening up the possibilities for on-chip integration in the integrated circuits
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
