Study of frequency-dependent plasmonic enhancement of a circular disk nano-optical antenna array using a femtosecond laser frequency comb

Abstract

In this paper, we report the study of the frequency-dependent plasmonic enhancement of a circular disk nano-optical antenna array and the photo-response of the optical antenna enhanced photodetector at different frequencies using a femtosecond (fs) laser frequency comb. A fs-laser frequency comb can provide hundreds of evenly spaced harmonic frequencies and thus allows simultaneous measurement of the plasmonic optical antenna enhancement effect at these harmonic frequencies. This offers a highly efficient frequency-dependent measurement approach compared to the conventional method of modulating of a c.w. laser, which measures the frequency response at each frequency. The impulse response of the circular disk nano-optical antenna array and the electric-field (E-field) distribution profile are simulated under a fs laser illumination. The light intensity spectrum is simulated and verified to have uniform intensities on the harmonic frequencies within the ±5 GHz frequency range. The photocurrent densities in different regions of a GaAs p-i-n photodetector are analyzed together with their frequency dependence at the harmonic frequencies of the fs laser frequency comb with a repetition rate of f 0 = 94.2 MHz. A circular disk nano-optical antenna array enhanced GaAs p-i-n photodetector was fabricated and measured using a fs laser frequency comb with the same repetition rate. The nano-optical antenna can provide ~20 dB enhancement for the harmonic frequencies and extend the detector cut-off frequency from 2.4 GHz to 4.2 GHz.

Dynamic beam-steering of graphene-based terahertz cross Yagi–Uda antenna with a theoretical approach

“…This vital and critical characteristic facilitates optical fields manipulation using the plasma resonances of metallic particles [2], which opens a promising solution to design photonic integrated circuits (PICs) [3]. Several studies have been done on PAs, which play major roles in PICs such as devices to redirect the incident light or control the emission from point sources [4,5], photodetection [6], energy harvesting [7], sensing [8], and wireless on-chip links [9]. Assessing the electromagnetic performance of PAs has attracted much more attentions [10].…”