A new publication from Opto-Electronic Advances; DOI 10.29026/oea.2022.200100 considers polarization-switchable plasmonic emitters.
Plasmonic antennas in analogy with the microwave and radio-wave antennas can manipulate light at nanometer scales, and they attracted enormous attentions in recent years. Various plasmonic antennas were designed to tailor emission directions and emission polarization states. However, it is difficult to dynamically tune and switch emission polarization states of plasmonic antennas (or emitters) at nanometer scales owing to weak light-matter interactions in natural materials. By now, polarization-switchable plasmonic antennas (or emitters) have not been reported.
The authors of this article propose using a control laser beam to induce a bubble (n=1.0) in water (n=1.333), which is similar to boiling water in a kettle with fire, to obtain a large index variation as high as |Δn|=0.333, and the emission polarization of an ultra-small plasmonic emitter (~0.4λ2) was dynamically switched for the first time, as shown in Figure 1. The plasmonic emitter consisted of two orthogonal subwavelength metallic nanogroove antennas on a metal surface, and the separation of the two antennas is only sx=120 nm. Because of a large refractive index variation (|Δn|=0.333), the phase difference (φ) between the emission light from the two antennas was greatly changed when a microbubble emerged in water under a low-intensity control laser. As a result, the emission polarization of the ultra-small plasmonic emitter was dynamically switched from an elliptical polarization state to a linear polarization state, and the change of the degree of linear polarization is as high as Δγ≈ 0.66. This ultra-small polarization-switchable plasmonic emitter might increase flexibilities and communication capacities in inter-chip optical communications and quantum communications.
Article reference: Chen JJ, Gan FY. Polarization-switchable plasmonic emitters based on laser-induced bubbles. Opto-Electron Adv 5, 200100 (2022). doi: 10.29026/oea.2022.200100
Keywords: plasmonic emitters / nanometer scales / polarization manipulation / dynamical switching / bubbles
