TY - JOUR

T1 - Evaluation of the Efficiency of Generation of Terahertz Surface Plasmon Polaritons by the End-Fire Coupling Technique

AU - Gerasimov, Vasily Valerievich

AU - Nikitin, Alexey Konstantinovich

AU - Lemzyakov, Alexey Georgievich

AU - Azarov, Ivan Aleksandrovich

N1 - The work was done on the equipment of the shared research center SSTRC on the basis of the Novosibirsk FEL at BINP SB RAS. Публикация для корректировки.

PY - 2023/8

Y1 - 2023/8

N2 - One of the most important problems in the plasmonics of the terahertz (THz) range, which is actively developing now, is the efficient generation of surface plasmon polaritons (SPPs). The simplest and most promising technological technique of photon excitation of THz SPPs is through diffraction of radiation on the edge of the conducting surface of the sample (the end-fire coupling technique). In this paper, we experimentally evaluated the efficiency of the generation of monochromatic THz SPPs (λ0 = 141 μm) by this method with a sample in the form of a cylindrical segment, the convex surface of which has a gold layer coated by zinc sulfide (ZnS) with thickness d = 0–2 µm. Such configuration of the surface supporting the SPPs not only shields the detector from parasitic bulk waves arising during diffraction but also enables one to change the distribution of the SPP field in the air by varying the coating layer thickness d. On an uncoated gold surface, the SPP generation efficiency was η ≈ 20%. In the presence of a ZnS layer on the gold, the SPP generation efficiency gradually increased with d, reached the maximum (ηmax ≈ 60%) at d ≈ 1 μm, and then gradually decreased. Theoretical analysis showed that the efficiency of the SPP generation can be raised up to 80% due to the selection of an optimal SPP field profile via variation of the thickness of the dielectric layer on the metal surface, as well as with optimal incidence of the focused radiation on the edge of the sample.

AB - One of the most important problems in the plasmonics of the terahertz (THz) range, which is actively developing now, is the efficient generation of surface plasmon polaritons (SPPs). The simplest and most promising technological technique of photon excitation of THz SPPs is through diffraction of radiation on the edge of the conducting surface of the sample (the end-fire coupling technique). In this paper, we experimentally evaluated the efficiency of the generation of monochromatic THz SPPs (λ0 = 141 μm) by this method with a sample in the form of a cylindrical segment, the convex surface of which has a gold layer coated by zinc sulfide (ZnS) with thickness d = 0–2 µm. Such configuration of the surface supporting the SPPs not only shields the detector from parasitic bulk waves arising during diffraction but also enables one to change the distribution of the SPP field in the air by varying the coating layer thickness d. On an uncoated gold surface, the SPP generation efficiency was η ≈ 20%. In the presence of a ZnS layer on the gold, the SPP generation efficiency gradually increased with d, reached the maximum (ηmax ≈ 60%) at d ≈ 1 μm, and then gradually decreased. Theoretical analysis showed that the efficiency of the SPP generation can be raised up to 80% due to the selection of an optimal SPP field profile via variation of the thickness of the dielectric layer on the metal surface, as well as with optimal incidence of the focused radiation on the edge of the sample.

KW - coupling efficiency

KW - integrated optics

KW - surface plasmon polaritons

KW - terahertz region

KW - thin layers

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85168859264&origin=inward&txGid=960d4df4be9d92a386c00e47664c30b1

UR - https://www.mendeley.com/catalogue/0b222ff7-3b5e-34de-aa96-f9f82470a502/

U2 - 10.3390/photonics10080917

DO - 10.3390/photonics10080917

M3 - Article

VL - 10

JO - Photonics

JF - Photonics

SN - 2304-6732

IS - 8

M1 - 917

ER -