Compact wavelength add-drop multiplexers using Bragg gratings in coupled dielectric-loaded plasmonic waveguides

Design of an IMI optical 2 × 4 decoder circuit based on square disk resonators

This paper presents the design of a 2×4 decoder that was developed by using the finite element method (FEM) in conjunction with the COMSOL version 5.5 software. Insulator-metal-insulator (IMI) waveguides with four substructures were used in the fabrication of the plasmonic decoder. Gold is used as a conducting material. This is a challenge for us, while Teflon is used as a dielectric material in the fabrication process. The dimensions of this part are 1090 nm by 400 nm. At an operating wavelength of 1550 nm, the transmission threshold (T t h r e s h o l d ) of this scheme has been determined to be 10%. In order to assess the effectiveness of the plasmonic decoder, it is recommended that the modulation depth (MD), contrast ratio (CR), and insertion loss (IL) parameters be carried out. Both the highest values of CR and MD are 12.33 decibels, and the maximum value of MD is 99.96%. It is because of these qualities that this work is distinguished from earlier works.

Realization of an optical nanostructure 4×1 multiplexer based on metal-insulator-metal plasmonic waveguides

The optical multiplexer was created at a nanoscale plasmonic structure utilizing the finite element method (FEM) with COMSOL version 5.5 software to enable maximum light confinement, high-speed optical systems, and a tiny structure. The metal-insulator-metal technology at a nanoscale dimension is used for creating the 4×1 multiplexer. In this design, the transmission threshold (T t h r e s h o l d ) is selected to be 100% for separating between logic "1" and logic "0" at a 1310 nm operating wavelength. The modulation depth (MD), contrast ratio (CR), and insertion loss (IL) characteristics were explained to evaluate the performance of the multiplexer. The CR has 3.48 dB, the MD offers an ideal performance with 95.28 %, and the IL has 3.31 dB.

3D Dirac semimetal supported thermal tunable terahertz hybrid plasmonic waveguides

By depositing the trapezoidal dielectric stripe on top of the 3D Dirac semimetal (DSM) hybrid plasmonic waveguide, the thermal tunable propagation properties have been systematically investigated in the terahertz regime, taking into account the influences of the structure of the dielectric stripe, temperature and frequency. The results manifest that as the upper side width of the trapezoidal stripe increases, the propagation length and figure of merit (FOM) both decrease. The propagation properties of hybrid modes are closely associated with temperature, in that when the temperature changes in the scope of 3-600 K, the modulation depth of propagation length is more than 96%. Additionally, at the balance point of plasmonic and dielectric modes, the propagation length and FOM manifest strong peaks and indicate an obvious blue shift with the increase of temperature. Furthermore, the propagation properties can be improved significantly with a Si-SiO₂ hybrid dielectric stripe structure, e.g., on the condition that the Si layer width is 5 µm, the maximum value of the propagation length reaches more than 6.46 × 10⁵µm, which is tens of times larger than those pure SiO₂ (4.67 × 10⁴µm) and Si (1.15 × 10⁴µm) stripe. The results are very helpful for the design of novel plasmonic devices, such as cutting-edge modulator, lasers and filters.

Add drop multiplexers for terahertz communications using two-wire waveguide-based plasmonic circuits

Terahertz (THz) band is considered to be the next frontier in wireless communications. The emerging THz multiplexing techniques are expected to dramatically increase the information capacity of THz communications far beyond a single channel limit. In this work, we explore the THz frequency-division multiplexing modality enabled by an add-drop multiplexer (ADM) design. Based on modular two-wire plasmonic waveguides fabricated using additive manufacturing and metallization techniques, we demonstrate four-port THz ADMs containing grating-loaded side couplers for operation at ~140 GHz carrier frequency. Particular attention is paid to the design of plasmonic waveguide Bragg gratings and directional couplers capable of splitting broadband THz light into spectral and spatial domains. Finally, we demonstrate multi/demultiplexing of THz signals with bit rates up to 6 Gbps using the developed ADMs. We believe that the proposed plasmonic circuits hold strong potential to provide robust integrated solutions for analog signal processing in the upcoming THz communications.

Using 3D-printed two-wire plasmonic circuits, the authors demonstrate add-drop THz multiplexers featuring a grating-loaded side coupler design. They confirm the channel Drop, Add, and Through actions using ~6 Gbps data streams at ~140 GHz carrier frequency.

Ultralong propagation of a surface plasmon polariton wave within an ultrawide bandwidth via phase-sensitive optical parametric amplification

The propagation length enhancement of surface plasmon polariton (SPP) waves could lead to practical applications. This Letter proposes the numerically verified phase-sensitive nonlinear χ⁽²⁾-based optical parametric amplification (OPA) for ultralong propagation of a SPP wave within an ultrawide bandwidth. The strong nonlinear interaction between the SPP mode and the hybrid guided mode, which limits the length enhancement, is mitigated in a silver-coated linearly chirped periodically poled lithium niobate planar waveguide via slowly phase-matched OPA. Obtained results indicate an ultralong propagation length for a SPP mode of about 4 cm when a 135 MW/cm pump intensity is launched. The acceptance bandwidth of the amplified SPP shows its dependency on the pump intensity; for a pump intensity range between 70 and 135 MW/cm, the acceptance bandwidth is still ultrawide, varying from 28 to 18 nm, respectively.