Andor Technology's IDUS DU420A-BU camera has been used by a team from the University of Illinois in research that could lead to advances for efficient solar energy photoelectric devices development.
Nanoscale antennas hold out the promise of higher-resolution optical imaging of nano objects, including proteins and DNA molecules, and converting solar energy into electricity at high efficiencies.
A team from the University of Illinois led by Nicholas Fang and Kimani Toussaint has demonstrated a 1,000-fold increase in the UV-visible optical response of devices based on nanoantennas periodic arrays.
Nanoantennas are similar to radio and microwave antennas, except that they can absorb a specific range of wavelengths of light dependant on their geometry and size.
Bowtie nanoantennas consist of two triangular pieces of gold with their tips facing each other in the shape of a miniature bowtie.
They take energy from the illuminating beam and compress it into the nanometre gap separating the two triangles.
The result is a concentrated spot of light that is many times more intense than the incoming laser beam.
Fang and Toussaint's team fabricated a 50mm-thick gold bowtie nanoantenna (BNA) composed of two equilateral triangles with 140nm sides separated by a 20nm gap and acquired the emission spectra when illuminated with 780nm laser light using the Andor IDUS DU420A-BU camera.
When individual antennas were gathered into arrays with 500nm centre-to-centre spacing, the team found that the large focal intensity enhancement of the single BNA was boosted by a factor of 1,000.
More importantly, resonantly excited arrays exhibited uniform emission over a spectral region of more than 250nm.
The team believes that optimisation of the nanoantenna array periodicity may lead to even more efficient devices.
Recent studies have also suggested the possible development of nanoantenna-based solar energy collection devices with conversion efficiency of up to 80 per cent - compared with 20 per cent for traditional solar cells - as well as the use of nanoantennas arrays as nanoscale light sources to scan and image biological molecules or synthetic nano-objects such as carbon nanotube bundles.
Antoine Varagnat, product specialist at Andor, said: 'Nanoantennas have come under greater scrutiny over the last few years, due to their potential to provide nanoscale, cost-effective optical probing or high-efficiency collection devices.
'Andor's IDUS CCD platform is ideally suited to the study of the key mechanisms at the origin of nanoantennas unique properties, namely nonlinear second harmonic generation (SHG) and complex photoluminescence.
'IDUS's high UV to near-infrared response, ultra-low noise and high dynamic range allow the analysis of a wide range of intensities of these broadband phenomena, providing the accurate information essential to the fine-tuning and optimisation of the amplification properties of these nanoantennas.
'And the IDUS BU UV-enhanced back-illuminated CCD was the right choice for the team's 350-660nm detection requirement.'
