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Plasmonic Demultiplexer With Tunable Output Power Ratio Based on Metal-Dielectric-Metal Structure and E7 Liquid Crystal Arrays
摘要： A novel tunable plasmonic demultiplexer is proposed and numerically investigated by finite element method(FEM). It consists of two half-nanodisk cavities and two sets of E7 liquid crystal arrays which are side-coupled to three metal-dielectric-metal(MDM) waveguides. The demultiplexer can split the input lights into two parts corresponding to port1(1310nm) and port2(1550nm). The Q-factors of port1 and port2 are 54.6 and 36, and the crosstalk values are -20.7dB and -29.9dB, respectively. Obviously, both channels have high Q-factors and low crosstalk value. Moreover, the E7 liquid crystal arrays play a key role in the whole structure, which makes the output power adjustable proportionally by adjusting the applied voltage. This novel feature greatly enriches the function of our demultiplexer. Using the electronical tunable birefringence characteristic of liquid crystal and its arrays structure paves a new way to realize practical on-chip plasmonic system, which can be widely used not only in demultiplexers but also in nanosensors, optical splitters, filters, optical switches, nonlinear photonic and slow-light devices.
关键词： on-chip plasmonic system,demultiplexer,surface plasmon polaritons(SPPs),Metal-dielectric-metal(MDM) waveguide
更新于2025-09-23 15:19:57
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Hot carrier dynamics in a dispersionless plasmonic system
摘要： Hot carrier dynamics in a broadband, dispersionless, plasmonic structure are studied using pump-probe measurements with 45 fs time resolution. The results obtained by simultaneous measurement of differential transmittance and reflectance show the influence of pump generated carriers on the probe generated plasmons. The dependence of decay time on the pump fluence is linear for the interband and intraband carrier excitation near the L-symmetry point in gold. However, 1.908 eV pump excitation, which allows both interband transition at the X-symmetry point and intraband excitation at the L-symmetry point, shows quadratic dependence of decay time on the pump fluence. Degenerate pump-probe measurements at 1.55 eV, which allow L-valley intraband excitations, highlight the difference in surface (reflection) and the bulk (transmission) mechanisms. Hot carrier relaxation time is in the 1–3 ps range for different excitation energies. Rise time, governed by the plasmon to hot carrier conversion and electron-electron scattering processes, is about 200 ± 35 fs for the hot carrier and hot plasmon excitation cases that increased to about 485 ± 35 fs when the pump is resonant with the interband transition at the X-symmetry point. Results show that the hot carrier dynamics are governed by the bulk metal band structure. The dipole matrix element for each of the transitions is estimated by density matrix calculations.
关键词： pump-probe measurements,gold band structure,differential transmittance,reflectance,plasmonic system,hot carrier dynamics
更新于2025-09-12 10:27:22