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This article examines the feasibility of integrating solid-state plasma surface p-i-n (S-PIN) diodes into on-chip slots using silicon-on-insulator technology. Two categories of solid-state plasma S-PIN diodes are characterized. Simulations analyze the current–voltage (I–V) characteristics, carrier concentrations, potential distribution, and thermal considerations of both single and dual S-PIN diodes, with optimization of their structural parameters and sizes. Experimental tests on fabricated S-PIN diodes of varying sizes with bias lines embedded in the on-chip slots show favorable I–V characteristics for both types of diodes. The measured results closely align with simulation predictions for the diodes' conduction onset voltages. Additionally, a cavity-backed slot antenna is proposed to evaluate and compare radiation characteristics resulting from integrating different types of S-PIN diodes. [ABSTRACT FROM AUTHOR]

In this paper, a wideband and high-gain circularly polarized (CP) antenna array with polarization-reconfigurable characteristics is presented based on the solid-state plasma (SSP). The proposed antenna is composed of switchable rotating radiation structures and a switchable feed network by simulating the different SSP branches. To investigate the CP operating mechanism, a reconfigurable CP element is designed through characteristic mode analysis (CMA). A switchable sequential-phase feed network is then proposed which can provide separately two rotational excitations. A spoof surface plasmon polariton (SSPP) is adopted for radiation patches to improve gain and axial ratio (AR) bandwidth. Finally, a high-gain and wideband 2 × 2 CP reconfigurable antenna array is designed. This array achieves left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) modes when different SSP branches are excited. The array has an overlapped impedance bandwidth of 61.9 % (3.17 to 6.01 GHz) and an overlapped AR bandwidth of 40.2 % (4.01 to 6.03 GHz) in two CP states, and the peak gain is 11.68 dBic.

The basic mechanisms of laser interaction with synthetic diamond are reviewed. The characteristics of the main regimes of diamond surface etching are considered. In addition to the well-known graphitization and ablation processes, nanoablation and accumulative graphitization, which have attracted relatively recent attention, are described in detail. The focus is on femtosecond (fs) laser exposure, which allows for the formation of a dense cold electron–hole plasma in the focal zone and minimal overheating in the surrounding area. This potentially opens the way to the development of unique laser-based technologies that combine physical and chemical processes for precise surface treatment and functionalization. The physical limitations that determine how precisely the diamond surface can be treated by short-pulsed laser radiation and possible ways to overcome them with the ultimate goal of removing ultrathin layers of the material are discussed. Special attention is paid to the novel possibility of inducing the local formation of point active defects—nitrogen vacancy (NV) complexes in the laser-irradiated zone. Such defects have been at the forefront of solid-state physics for the past thirty years due to continuous attempts to exploit their unique properties in quantum optics, quantum computing, magnetometry, probing, and other fields. Both regimes of NV center formation with and without graphitization of the diamond lattice are considered. Thus, it is shown that intense pulsed laser irradiation is a perfect tool for the processing of synthetic diamonds at the micro-, nano-, and even at the atomic level, which can be well controlled and managed. [ABSTRACT FROM AUTHOR]

• A highly integrated multistate continuous tunable AFSS absorber/reflector based on solid-state plasma. • A new SPiN diode with high carrier concentration. • The plasma AFSS absorber/reflector achieves real-time stealth capabilities without using switch diodes. Switchable absorber/reflector provides a flexible and controllable method for electromagnetic wave manipulation, offering new possibilities for applications in stealth technology, communication sensing, energy management, and other fields. This paper presents a high-integration multistate continuous tunable AFSS absorber/reflector based on solid-state plasma, utilizing the "metal-like" properties of solid-state plasma to achieve flexible control of electromagnetic wave. By controlling the variation of applied voltage, the designed absorber/reflector structure allows for continuous changes in absorption intensity within the range of 0 dB to −20 dB. Additionally, an intelligent AFSS absorber/reflector array structure consisting of 100 × 100 units is designed. By adjusting the applied voltage, the conductivity of this structure can continuously change from 0.1 S/m to 1 × 105 S/m, enabling the proposed AFSS absorber/reflector structure to vary its reflectance magnitude from −25 dB to 0 dB. [ABSTRACT FROM AUTHOR]

A low-loss, polarization-insensitive and tunable electromagnetically induced transparency (EIT) at terahertz frequency has been demonstrated in this paper. It is obtained by the excitation of the two resonators at the same time, which could be excited by the incident electric and magnetic fields separately. The metamaterial electromagnetically induced transparency (EIT) structure is composed of silver cross strip and silver cross block. The transmission spectrum's peak could reach as high as 0.97 and the frequency band that the transmission peak above 0.95 could reach 0.32 THz. In addition, through exciting different region of solid-state plasmas, the transmission window could be tuned in a narrow frequency band, which offers an effective approach to produce low-loss and tunable EIT metamaterials. [ABSTRACT FROM AUTHOR]

For the first time, this study demonstrates a reconfigurable antenna with electrical beamforming that is entirely integrated by semiconductor microfabrication technology. In this paper, a vertical structured array of solid‐state plasma which acts as a reconfigurable conducting wall to control the main beam direction of an antenna is proposed. In many conventional works, insufficient electrical conductivity of turned‐on plasma channels at the planar surface of PIN diodes causes an inherent large loss and low radiation efficiency of silicon‐based antennas. However, in this study, the overall performance of the antenna is notably enhanced by adopting the vertical plasma channels which solve the lower electrical conductivity problem of the surface‐type plasma structure. Accordingly, the proposed antenna achieves a high realized gain of more than 5 dBi over a frequency range of 27.5–29.6 GHz, even though it is comprised of lossy silicon with high permittivity. In addition, the low cost and electrically reconfigurable antenna, which benefits from the highly precise semiconductor fabrication process, is applicable to sub‐THz applications with a lightweight and compact sized feature. This work paves the way to make silicon antennas with commercial microfabrication technology a next‐generation antenna. [ABSTRACT FROM AUTHOR]

A novel multifunctional polarization converter (PC) based on the solid-state plasma (SSP) is proposed, which can switch two functions and adjust the working band. By energizing different parts of SSP resonators, the presented PC can accomplish three different operating states. In the state 1, this PC can operate in 6.12-9.50 GHz and the relative bandwidth (RB) is 43.3%, which can achieve the aim of the linear-to-circular polarization conversion (LCPC). In the state 2, the cross-polarization conversion (CPC) can be achieved in 4.62-8.34 GHz (the RB is 57.4%). Besides, in the state 3, such a PC can be implemented within a 7.92-10.34 GHz working band of CPC (the RB is 26.5%). All in all, the proposed PC can realize the function switchover between LCPC and CPC, and the operating bands of the CPC can be shifted flexibly between the states 2 and 3. The proposed PC has great potential values in antennas, imaging systems, electromagnetic devices and so on. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative reconfigurable antenna concept based on the dynamic definition of metal-like conductive solid-state plasma in high-resistivity silicon which are activated by the injection of direct current. By investigating of the solid-state plasma characteristics, the metallic properties of solid-state plasma are verified. And a demonstration prototype of plasma dipole reconfigurable antenna, which comprises 36 SPiN diodes, has been designed, fabricated, and tested. The results show that the resonance frequencies at 69 GHz, 64.3 GHz and 60 GHz can be easily achieved when the antenna works in the three different states by turning on or off different sections of the antenna, selectively. In addition, it is confirmed that the proposed reconfigurable antenna has the unique characteristics compared with the conventional one. • An innovative solid-state plasma reconfigurable dipole antenna has been realized based on SPiN diodes. • The solid-state plasma reconfigurable antenna prototype was designed, fabricated, and tested. • Three different frequencies can be easily achieved by turning on or off different sections of the antenna, selectively. [ABSTRACT FROM AUTHOR]

Abstract In this paper, an ultra-broadband multilayer tunable absorber (MTA) with the lumped resistors (LRs) is proposed, where a dielectric layer is sandwiched between three split square ring resonators and a continuous metallic plane. It is noted that two truncated triangular ring-shaped and Y-shaped solid-state plasma resonators (SSPRs) are embedded in the substrate. Three solid-state plasma cylinders are also inserted between the truncated triangular ring-shaped resonators and Y-shaped SSPRs. External two split square rings and a truncated triangular ring are loaded with the lumped elements. After calculation, for the TE wave, the absorption rate is larger than 90% in a certain frequency region which covers 7–16.25 GHz. Moreover, the proposed MTA is polarization independent at normal incidence. The absorption mechanism and properties also are investigated. The obtained results illustrate that the absorption performance and operating frequencies can be tailored when the different SSPRs are excited. [ABSTRACT FROM AUTHOR]

Optically induced electron–hole plasmas in silicon are used to perform radiation pattern tuning. The antenna is a slot loaded microstrip patch and the effect of illumination is shown to produce beam switching in the radiation patterns of certain modes while other modes are left unaffected. The structure is specifically designed to make the best use of currently available miniature laser sources to form a compact tunable package. Modelled and measured results for tuning of the radiation patterns and frequency response are presented. The effect of the losses incurred by the plasma along with the losses in the optically transparent ground plane are quantified in both simulation and measurement. This forms the basis for designing other types of optically tunable miniature antennas based on the structure presented. [ABSTRACT FROM AUTHOR]

We report an analysis on a phonon spectral function of a solid-state plasma formed in a doped semiconductor. Real and imaginary parts of phonon propagators are evaluated including carrier screening effects within a random phase approximation, and finite-temperature spectral behavior of the phonon spectral function is examined in terms of plasmon-phonon coupled modes and quasiparticle excitation mode of the plasma. The results are applied to the case of conduction electrons in a wurtzite GaN considering carrier-phonon coupling channel via polar optical phonons. We show that the dispersion relations of the plasmon-LO phonon coupled (‘upper’ and ‘lower’) modes and the character of the additional modes via single quasiparticle excitations are heavily associated with the nonlocal and dynamic behavior of the energy shift and collisional broadening of the dressed phonon propagator of the plasma. [ABSTRACT FROM AUTHOR]