We report spectrally selective IR absorption enhancement in the defect-free photonic crystal cavities, via Fano resonances. For a symmetric slab structure (air-slab-air membrane) with an absorptive layer in the center of the slab, enhanced absorption can be observed with enhancement factor ~180 for certain range of r/a values at wavelength of 4 μm. Similar results can also be achieved in an asy...

Multi Wall Carbon NanoTubes (MWCNT) are one-dimensional structures with diameters ranging between 5 and 30 nm and lengths up to hundreds of micrometers. They show a metallic-like behaviour and enhanced field emission capability; their sensitivity to the radiation is very peculiar, depending on their diameter and chirality. The wide range of their bandgaps (from 0.4 to o 6 eV) makes these device...

High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The pho...

The multispectral electromagnetic (EM) absorber based on the frequency selective surface (FSS) has been applied with interest in field of stealth technology due to its ability avoid detectors or guided weapons at multiple wavelengths simultaneously. absorption performance is generally accomplished by stacking different types FSS absorbers layers. Herein, a thin and flexible single-layer (MSLF) ...

Although far-IR – mm-wave astronomy has now been developing for several decades, access to this portion of the spectrum remains difficult and limited. Relative to their optical-wavelength counterparts, the submillimeter observatories are both small in units of wavelength and hot in units of photon energy, which imposes limits on their angular resolution and sensitivity. Nevertheless, even the m...

Results are reported on dual-band detectors based on a GaN/AlGaN structure operating in both the ultraviolet–midinfrared (UV– MIR) and ultraviolet–farinfrared (UV–FIR) regions. The UV detection is due to an interband process, while the MIR/FIR detection is from free carrier absorption in the emitter/contact followed by internal photoemission over the barrier at the GaN/AlGaN interface. The UV d...

In this paper, two suboptimum detectors are proposed for coherent radar signal detection in K-distributed clutter. Assuming certain values for several initial moments of clutter amplitude, the characteristic function of the clutter amplitude is approximated by a limited series. Using the Pade approximation, it is then converted to a rational fraction. Thus, the pdf of the clutter amplitude is o...

An experimental system in which correlated photons for radiometric measurements were used has been set up at the National Institute of Standards and Technology. We use visible-IR pairs of correlated photons produced by means of optical parametric downconversion to measure the radiance of a high-temperature IR source at 3.415 and 4.772 mum in an intrinsically absolute manner (i.e., without requi...