Engineering Optical Antenna for Efficient Local Field Enhancement

Optical antennas have been widely used for variety of applications such as sensitive photodetection, efficient light emission, high-resolution imaging, heat-assisted magnetic recording, and surface-enhanced Raman spectroscopy (SERS) because they can capture and focus propagating electromagnetic energy into sub-diffraction-limited areas and vice versa. However, widespread application of optical antennas has been limited due to lack of appropriate methods for uniform and large area fabrication of antennas, as well as difficulty in achieving an efficient design with small mode volume (gap spacing 8 compared to the arch-dipole antenna array; this is two orders of magnitude stronger than that obtained from the standard dipole antenna array fabricated by e-beam lithography. Because the antenna gap spacing--a critical dimension of the antenna--can be defined by deep-UV lithography, efficient optical antenna arrays with sub-10 nm gap can be mass-produced using current CMOS technology.