Tham khảo tài liệu 'recent optical and photonic technologies part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 198 Recent Optical and Photonic Technologies and do not excite the particle plasmon mode. As a result the higher frequency components do not couple across the medium and are not radiated into the far-field. Fig. 10. A Time-domain waveforms of the far-field THz transmission through a 3 0-mm thick ensemble of copper particles with average particle diameters ranging from 85 pm to 670 pm. B Power spectra of the transmission through the particle ensembles normalized by the power spectrum of the incident THz pulse. C Total integrated transmitted power through the particle ensembles with respect to the average diameter of the particles that constitute the ensemble. illustrates polar plots of the intensity distribution of the transmitted THz radiation through a L 3 mm thick ensemble of densely-packed copper particles with mean diameters of 85 pm 283 pm and 372 pm. For the ensemble of 85- pm diameter particles the transmission polarization preserves the incident linear polarization indicating a high degree of electromagnetic coupling across the ensemble. The diminished polarization of the transmission through the ensemble of 283- pm diameter particles indicates reduced electromagnetic coupling. This observation coincides with a four-fold reduction in the transmitted intensity through the ensemble of 283- pm diameter particles relative to that of the 85- pm diameter particles. Terahertz Time-Domain Spectroscopy of Metallic Particle Ensembles 199 Fig. 11. Polar plot of the intensity distribution of the THz pulse transmitted through a thick ensemble of copper particles with average diameters of A 85 pm B 283 pm and C 372 pm. The transmission through the ensemble of 372- pm diameter particles is nearly unpolarized indicating that the transmitted energy is not coherently channeled across the extent of the ensemble. For the ensemble of 372- pm diameter particles the transmitted intensity is almost fully extinguished. The effect of the particle diameter on the .
