Study of frequency-dependent plasmonic enhancement of a circular disk nano-optical antenna array using a femtosecond laser frequency comb
| Autor: | Ainaz GhafaryAghdam, Guiru Gu, Michaela Sullivan, Boyang Xiang, Cheryl Schnitzer, Xuejun Lu, Lin Li, Thitikorn Kemsri |
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| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Frequency response Materials science Acoustics and Ultrasonics business.industry Physics::Optics Photodetector 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Laser 01 natural sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials law.invention Antenna array Light intensity Frequency comb Optics law 0103 physical sciences Femtosecond Antenna (radio) 0210 nano-technology business |
| Zdroj: | Journal of Physics D: Applied Physics. 52:385104 |
| ISSN: | 1361-6463 0022-3727 |
| DOI: | 10.1088/1361-6463/ab2ab8 |
| Popis: | 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 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. |
| Databáze: | OpenAIRE |
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