This paper provides a comprehensive review of advanced radio frequency (RF) filter technologies available in miniature chip or integrated circuit (IC) form for wireless communication applications. The RF filter technologies were organized according to the timeline of their introduction, in conjunction with each generation of wireless (cellular) communication standards (1G to 5G). This approach enabled a clear explanation of the corresponding invention history, working principles, typical applications and future development trends. The article covered commercially successful acoustic filter technologies, including the widely used surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters, as well as electromagnetic filter technologies based on low-temperature co-fired ceramic (LTCC) and integrated passive device (IPD). Additionally, emerging filter technologies such as IHP-SAW, suspended thin-film lithium niobate (LiNbO₃ or LN) resonant devices and hybrid were also discussed. In order to achieve higher performance, smaller form factor and lower cost for the wireless communication industry, it is believed that fundamental breakthroughs in materials and fabrication techniques are necessary for the future development of RF filters.

With increasing challenges towards continued scaling and improvement in performance faced by electronic computing, mechanical computing has started to attract growing interests. Taking advantage of the mechanical degree of freedom in solid state devices, micro/nano-electromechanical systems (MEMS/NEMS) could provide alternative solutions for future computing and memory systems with ultralow power consumption, compatibility with harsh environments, and high reconfigurability. In this review, MEMS/NEMS-enabled memories and logic processors were surveyed, and the prospects and challenges for future on-chip mechanical computing were also analyzed.

Silicon-based polarization-encoding quantum key distribution (QKD) has been extensively studied due to its advantageous characteristics of its low cost and robustness. However, given the difficulty of fabricating polarized independent components on the chip, previous studies have only adopted off-chip devices to demodulate the quantum states or perform polarization compensation. In the current work, a fully chip-based decoder for polarization-encoding QKD was proposed. The chip realized a polarization state analyzer and compensated for the BB84 protocol without the requirement of additional hardware, which was based on a polarization-to-path conversion method utilizing a polarization splitter-rotator. The chip was fabricated adopting a standard silicon photonics foundry, which was of a compact design and suitable for mass production. In the experimental stability test, an average quantum bit error rate of 0.59% was achieved through continuous operation for 10 h without any polarization feedback. Furthermore, the chip enabled the automatic compensation of the fiber polarization drift when utilizing the developed feedback algorithm, which was emulated by a random fiber polarization scrambler. Moreover, a finite-key secret rate of 240 bps over a fiber spool of 100 km was achieved in the case of the QKD demonstration. This study marks an important step toward the integrated, practical, and large-scale deployment of QKD systems.

Implementing hardware primitives into cryptosystem has become a new trend in electronic community. Memristor, with intrinsic stochastic characteristics including the switching voltages, times and energies, as well as the fluctuations of the resistance state over time, could be a naturally good entropy source for cryptographic key generation. In this study, based on kinetic Monte Carlo Simulation, multiple Artificial Intelligence techniques, as well as kernel density map and time constant analysis, memristive spatiotemporal variability within graphene based conductive bridging RAM (CBRAM) have been synergistically analyzed to verify the inherent randomness of the memristive stochasticity. Moreover, the random number based on hardware primitives passed the Hamming Distance calculation with high randomness and uniqueness, and has been integrated into a Rivest-Shamir-Adleman (RSA) cryptosystem. The security of the holistic cryptosystem relies both the modular arithmetic algorithm and the intrinsic randomness of the hardware primitive (to be more reliable, the random number could be as large as possible, better larger than 2048 bits as NIST suggested). The spatiotemporal-variability-based random number is highly random, physically unpredictable and machine-learning-attack resilient, improving the robustness of the entire cryptosystem.

We present a theoretical investigation, based on the tight-binding Hamiltonian, of efficient electric-field-induced three-waves mixing (EFIM) in an undoped lattice-matched short-period superlattice (SL) that integrates quasi-phase-matched (QPM) SL straight waveguides and SL racetrack resonators on an opto-electronic chip. Periodically reversed DC voltage is applied to electrode segments on each side of the strip waveguide. The spectra of χxxxx(3) and of the linear susceptibility have been simulated as a function of the number of the atomic monolayers for “non-relaxed” heterointerfaces, and by considering all the transitions between valence and conduction bands. The large obtained values ofχxxxx(3) make the (ZnS)3/(Si2)3 short-period SL a good candidate for realizing large effective second-order nonlinearity, enabling future high-performance of the SLOI PICs and OEICs in the 1000-nm and 2000-nm wavelengths ranges. We have made detailed calculations of the efficiency of second-harmonic generation and of the performances of the optical parametric oscillator (OPO). The results indicate that the (ZnS)N/(Si2)M QPM is competitive with present PPLN technologies and is practical for classical and quantum applications.

Cryogenic electronics refers to the devices and circuits operated at cryogenic temperatures (below 123.15 K), which are made from a variety of materials such as insulators, conductors, semiconductors, superconductors and topological materials. The cryogenic electronics are endowed with some unique advantages that cannot be realized in room temperature, including high computing speed, high power performance and so on. Choosing the appropriate refrigeration technology is critical for achieving the best performance of the cryogenic electronics. In this review, the cryogenic technology was divided into non-optical refrigeration and optical refrigeration, where non-optical refrigeration technologies are relatively conventional refrigeration technologies, while optical refrigeration is an emerging research field for the cooling of the chips. In the current work, the fundamental principles, applications and development prospects of the non-optical refrigeration was introduced, also the research history, fundamental principles, existing problems and application prospects of the optical refrigeration was thoroughly reviewed.