Near-field mapping of dipole nano-antenna-coupled bolometers

Abstract

The near-field characteristics of single, double, and arrays of connected dipole nano-antennas coupled to bolometers were studied by infrared scattering scanning near-field optical microscopy (s-SNOM) and analyzed by numerical simulations. Results were consistent with classical antenna theory showing the expected p phase difference across the terminals of the dipoles. However, according to the observed differences between the measurements and simulations, the symmetry of the amplitude signal appeared to be sensitive with respect to the position of the bolometric element relative to the dipoles. The effect of the position of the bolometer on the associated near-field distribution suggests an influence on the coupling and efficiency of energy transfer into these detectors, which could be important for determining tolerances in the fabrication of such devices. These results show how near-field measurements in general can provide critical information to guide the design of nano-antennas, nano-antenna-phased arrays, and integrated photonic devices.

Near- and far-field measurements of phase-ramped frequency selective surfaces at infrared wavelengths

“…5 where realized gain is defined as the ratio of the radiated power in each direction to the power of the incident beam. For the phase-ramped loops, the measured deflected angle is 23 while the phase-ramped patches have a deflected angle of 24 , which is relatively close to the calculated values of 25 for both structures. One difference between the calculated and measured beam deflection angle is that the calculation is based on values of reflected phase obtained from simulations of uniform arrays of elements while the measurement is of the phase-ramped structures having different size elements.…”

Array truncation effects in infrared frequency selective surfaces

“…The interfering beams are sampled with a HgCdTe (MCT) detector, using a lock-in amplifier to sample the signal at the second-harmonic of the AFM tip dither frequency. The intensity at the detector can be expressed as follows [19,22,25…”

“…Here E scat is the field of the scattered sample beam, E ref is the field of the reference beam, φ is the phase difference between the two beams, and I b represents a background signal which is not related to either the sample signal or reference beam. The terms which do not oscillate according to φ are diminished significantly due to the use of the lock-in amplifier as well as the orthogonally polarized excitation and detection scheme [17,19,20,22,23,25]. In order to generate amplitude and phase images, several data sets are taken over the sample area of interest at different discrete reference phases.…”

“…The far-field measurements were carried out using an FTIR based ellipsometer in reflectivity mode, while the near-field measurements were made using scattering-scanning near-field optical microscopy (s-SNOM). Measurements of local electric field distributions using s-SNOM at mid-IR wavelengths have been shown recently for metamaterial samples [12,[17][18][19], as well as antennas [20][21][22], transmission lines [23,24], and phase-ramped structures [25]. The data presented in this report show the effects of truncation on the near-and far-field performance of a mid-IR metasurface by comparing the infinite array response with that of 11x11 arrays, 7x7 arrays, 3x3 arrays, and single square loops with a large periodicity.…”

Fast response of superconducting hot-electron bolometers with a twin-slot nano-antenna for mid-infrared operation

“…al. reported the near-field mapping using by dipole nano-antenna-coupled bolometers at the wavelength of 10.6 µm, 6 which indicated that the nano-antenna effectively functioned. In order to improve the response performance of infrared detectors, we have also been studing the nano-antennas.…”