Tamm plasmons (TPs), whose plasmon modes are confined at the Bragg reflector/metal interface due to the photonic stopband of the reflector and the negative dielectric constant of the metal, exhibit many advantages over the conventional surface plasmons (SPs) and potential applications in sensors, filters, optical circuits and light-emitting devices. In this paper, a TP-cavity structure has been proposed for accelerating the light emission and alleviating the large metal loss, which is hopeful for solving the efficiency droop and “green gap” problems in InGaN green light-emitting diodes (LEDs). The light emission performance of TP-cavity LEDs was systematically investigated based on transfer matrix and finite-difference time domain methods. Purcell factor (F_p) and light extraction efficiency (LEE) were both remarkably enhanced, which would be attributed to the presence of the TP and/or SP modes induced by the TP-cavity structure. In addition, two important factors including the thicknesses of the top Ag film and medium layer were investigated in detail and taken into account for the balance between the F_p and the LEE. Finally, light emission intensity was significantly enhanced for the TP-cavity green LEDs after the structure optimization as compared to the conventional green LEDs.

In this research, we propose a simple and novel graphene-black phosphorus composite structure. Through the coupling mechanism of bright–bright mode, four layers of graphene and one layer of black phosphorus produce a quadruple plasmon-induced transparency (PIT) effect. The response of the proposed structure to the angle of polarized light is investigated, and it is found that the sensitivities of graphene and black phosphorus to the polarization angle of light are different. In addition, the dynamic regulation of PIT by the Fermi level of graphene and the carrier concentration of black phosphorus are discussed. The modulation depths of the fivefold optical switching are 96%, 99%, 87%, 93%, and 80%, respectively. The quadruple PIT can also be converted into triple PIT, in which single, dual, or triple optical switching are realized, respectively. Finally, with the change in the refractive index of the environment medium, the sensitivity response of the proposed structure is as high as 4.790 THz⋅RIU−1. We believe that this research will contribute to the development of optical switches, modulators, and sensors.

In this study, a novel silica-graphene–silica periodic graphene structure consisting of six graphene semi-rings is proposed. The structure is based on a three-layer graphene metamaterial with a semicircular ring that achieves a tunable double plasmon-induced transparency (PIT) effect. In the proposed structure, the double-PIT window can be switched simultaneously at multiple frequencies through the dynamic tunability of graphene. Besides, the sensitivities of the refractive index for the PIT windows are investigated with the maximum values of 1.42 THz RIU⁻¹ and 1.09 THz RIU⁻¹, respectively, indicating the structure’s performance as a terahertz sensor. Overall, it shows the potential of PIT effect in graphene metamaterials in controlling electromagnetic field responses. It has made positive contributions to the development of terahertz technology and related fields.

Binary metal layers composed of a grating and a thin film are designed for high-responsivity metal–insulator–metal (MIM) near-infrared hot-electron photodetectors (HEPDs). The binary metal grating structure HEPDs demonstrate a strong asymmetrical optical absorption and result in a high current responsivity. In our devices, the top and bottom absorption ratio is as high as 76:1, much higher than that in the traditional grating structure HEPDs. The maximum zero-biased responsivity is 0.585 mA/W at 1550 nm by employing a five-step electrical model, which is 3.42 times that of the traditional silver grating structure devices. Simply changing the grating period enables spectrally selective photodetection covering a wide range of 500 nm at the near-infrared band with net absorption higher than 0.95 and linewidths narrower than 0.7 meV.

Planar, nanopillar and Al nanosphere structure AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) were numerically investigated via a three-dimensional finite difference time domain (3D FDTD) method. The three types of DUV-LEDs were compared and analyzed in terms of light extraction efficiency (LEE), Purcell factor (F_P) and modulation bandwidth. The results showed that nanopillar structure DUV-LEDs with optimal nanopillar height, width and spacing can enhance transverse electric (TE)-polarized LEE to 39.7% and transverse magnetic (TM)-polarized LEE to 4.4%. The remarkable improvement was mainly due to the increased scattering effect, decreased absorption of the p-GaN layer and total internal reflection (TIR) effect. After adopting the Al nanospheres, the TE-polarized modulation bandwidth was increased by 71 MHz and the TM-polarized LEE was enhanced approximately 4.3-fold as compared to the nanopillar LED structure, while the Al nanosphere diameter was 120 nm. The reasons for promotion are mainly attributed to the coupling behavior of diploe and localized surface plasmon induced by Al nanospheres. The designed structures provide a meaningful solution for realization of high-efficiency DUV-LEDs.

We design and demonstrate a cascaded SiN-based RGB coupler with dual-mode interference (DMI) for a micro laser scanning image projector. The DMI configuration in SiN-based waveguides mitigates the adverse effects of self-image point deviation caused by wavelength dispersion, achieving decreased device length and high transmission efficiency. The underlying mechanisms are discussed based on coupled-mode theory and 3D finite difference time domain simulation. A small footprint of 3 µ m × 70 µ m is achieved for the RGB coupler device without input/output circuits, and the insertion losses are less than 0.56 dB at RGB wavelengths. There are two orders of magnitude reduction in device length as compared with the conventional S i O 2 -based RGB coupler, which greatly promotes the miniaturization of the couplers and displays integration advantages with a laser diode and waveguide photodetector. In addition, the 3 dB bandwidth is over 50 nm for the coupler, and it demonstrates good fabrication tolerance. This design can further be integrated into visible light communication systems and applied to visible light integrated photonics.