Reconfigurable Parametric Amplifications of Spoof Surface Plasmons

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.

Nonmagnetic Spoof Plasmonic Isolator Based on Parametric Amplification

“…Theoretical analysis indicates that when the pump intensity reaches a certain constant, the signal wave will be amplified. [11] As expected, the reciprocal transmissions of the forward and backward signal waves are verified by turning the pump off, as shown in Figure 3b. When the pump wave is switched to an on state, the amplification of the forward signal can be observed, provided that the signal gain compensates for the losses of structure and varactors.…”

“…To achieve a large isolation ratio, high signal gain generated from the designed PA is necessary. Based on the theoretical model for spoof plasmonic parametric amplification, [ 11 ] we can predict that the maximum signal gain can be realized at the nonlinear length of about 5λ (λ is the signal wavelength of SSPP). Thus, we fabricate the spoof plasmonic PA consisting of 35‐unit cells loaded with the varactors (MAVR‐011020‐1141), corresponding to the nonlinear length of 87.500 mm.…”

“…[8][9][10]37] Motivated by these merits, many circuit elements have been fabricated and implemented experimentally in the spoof plasmonic platform. [11][12][13][14][15] However, most SSPP devices realized thus far are passive and reciprocal. In integrated electronic circuits, nonreciprocity is highly desired to reach asymmetric signal transmission and modulation, and nonreciprocal microwave components, such as isolators, circulators, and gyrators, play a critical role in modern communication, radar, and sensing systems.…”

Reprogrammable Spoof Plasmonic Modulator

“…[ 7,8 ] Compared to conventional waveguides, such as microstrip in microwave frequencies, the SSPP waveguide can effectively suppress crosstalks between different waveguides when signals are transmitted in parallel. [ 9–12 ] Benefiting from these advantages, some SSPP‐based circuit components have been designed and demonstrated experimentally on the spoof plasmonic platform, [ 13–18 ] such as reconfigurable SSPP parametric amplifier, [ 13 ] nonmagnetic spoof plasmonic isolator, [ 14 ] and wireless body sensor networks. [ 15 ] In general, most research efforts on reconfigurable SSPP devices, usually by integrating active chips, are mainly focused on the physical phenomena and the manipulations of surface EM waves in an analog way, neglecting the digital‐programmable potentials.…”

Miniaturized Spoof Plasmonic Antennas with Good Impedance Matching

“…Spoof surface plasmon polaritons (SSPPs), also known as plasmonic metamaterials, inherit the properties of field confinement and local field enhancement from natural surface plasmon polaritons (SPPs) by decorating metal surfaces with subwavelength corrugations [ 6 , 7 , 8 , 9 ]. Thus far, various devices have been proposed based on SSPPs, such as filters [ 10 , 11 , 12 , 13 ], couplers [ 14 , 15 ], amplifiers [ 16 , 17 , 18 ], harmonic generators [ 19 , 20 , 21 ], sensors [ 22 , 23 , 24 ] and lens [ 25 , 26 ]. The integration of spoof plasmonic devices/components into traditional circuits requires conversion from guided waves to spoof plasmonic waves.…”