Integrated plasmonic nano-antenna devices

Surface plasmon polaritons (SPPs) are evanescent electromagnetic waves propagating at the interface between a dielectric and a metal. Following recent developments, they may find application in future generations of opto-electronic devices. An example of a plasmonic device is a nano-antenna. Although nano-antennas are applied in biological sensing, imaging and nano-particle manipulations, they are passive devices that must be driven by an external source. As combining plasmonic nano-antennas with micro-lasers is the main focus of this thesis, schemes for integrating them are suggested and some applications explored (e.g., surface enhanced Raman scattering (SERS)). The designs and theoretical analyses of the devices are based upon the finite difference time domain (FDTD) method and MATLAB codes. Then, these optical components are fabricated by an electron beam evaporator, Focused Ion Beam (FIB) milling and Electron Beam Lithography (EBL) systems as well as other techniques. Finally, some of the devices are characterised by micro/Raman-photoluminescence (PL). Initially, schemes for integrating plasmonic nano-antennas with micro-lasers (based upon either quantum wells or quantum dots) are studied and the use of linear or parabolic tapers to couple light from the latter into the former is proposed. This significantly increases their coupling efficiency (to about 30%) compared with excitations imposed by external large-area semiconductor lasers (with efficiencies lower than 1%). It is also found that these nano-antenna lasers can generate high-intensity electric fields inside the nano-antennas; for example, the use of a parabolic taper can yield an electric field enhancement of 7 (for a 50 nm air gap). Alternatively, slot waveguides are proposed for coupling light into nano-antennas without significant reflection (less than 5%) when compared with the direct excitation of nano-antennas by micro-lasers (reflection above 50%). Finally, surface enhanced Raman scattering (SERS) sensors based upon nano-antennas are studied. Broadband nano-antennas based upon Charnia-like and spiral structures are proposed. It is shown that using these devices, electric field enhancements above 8.8 can be achieved over a wide range of wavelengths. Also, a plasmonic staircase nano-antenna, which can provide an electric field enhancement as high as 31 and a SERS enhancement factor above 2 million, is analysed and characterised.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2013

Author dc:creator

• Li, Ziyuan

• Surface enhanced Raman scattering
• Plasmonic nano-antennas
• Micro-lasers

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/16182

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/52683