New nano-structure spectrometer by introducing gold nano-pillars for spectral reconstruction ability improvement

As a new proposed spectrometer, the filter-based spectrometer uses a group of filters with known transmittance to modulate the spectrum of an incident light beam. After employing a post-processing algorithm, the spectrum of the beam can be reconstructed. For such spectrometers, the transmittance curve characteristics of the filters have a crucial impact on the spectrum reconstruction results. To better capture the details of the spectrum curve of the incident light beam, we propose a new nano-structure spectrometer by introducing gold nano-pillars to the photonic crystal (PC) filters. Because of the surface plasmon resonance effect of the gold nano-pillars, narrow bands will be generated on the transmittance curve of the new filters, which can improve the spectral reconstruction capability of the filters. In this paper, we first briefly introduce the principle of the filter-based spectrometer. Then, the transmittance curves of the filters are simulated by multiple random Gaussian functions according to the waveform of the transmittance curve of practical filters. And the simulated transmittance curves are used to reconstruct the spectrum of a beam to study their anti-noise capability. Next, new filters are designed by introducing gold nano-pillars to the PC filters. And their transmittance curves are calculated by the finite-difference time-domain (FDTD) approach. Finally, the spectrum reconstruction results are compared with those of the PC filters. The simulation results show that the introduction of gold nano-pillars can significantly improve the spectrum reconstruction ability of the PC filters.