Ya Fei Wu

This paper presents a copper-stacked substrate-integrated waveguide (CS-SIW) implemented in fan-out wafer-level packaging (FOWLP) to address a key manufacturing constraint of multilayer redistribution layers: continuous vertical cylindrical vias cannot be reliably stacked across multiple polyimide (PI) layers due to electroplated mushroom-cap non-planarity. The proposed via-strip conduction path forms a robust TE10 waveguide fully compatible with standard wafer-level processing, which is corroborated by SEM cross-sections of the stacked via–strip structures. Building on this platform, a CS-SIW multimode cavity was developed to extract the PI properties (ε_r≈3.05, tanδ≈0.021) over 210–250 GHz. Using the extracted parameters, a novel quasi-optical THz multibeam network in package is realized within the FOWLP stack. Broadband on-wafer measurements confirmed effective in-package routing and multibeam phase generation, closely matching simulation. The results demonstrate that the CS-SIW architecture enables manufacturable THz multibeam networks in FOWLP without bespoke steps, providing a practical path for short-reach chip-to-chip wireless links and integrated THz front-end systems.

Computational spectroscopy is a powerful tool across numerous disciplines, yet its development remains constrained by limited bandwidth and low light throughput of spectral encoders, which are inherent to optical materials and design frameworks. Here we overcome these challenges using transition metal dichalcogenides (TMDCs), leveraging their high refractive index (n > 4) and broadband transparency to achieve optical manipulation. This enables broadband spectral encoders that modulate light from the visible to short-wave infrared while maintaining light throughput above 65%. These characteristics originate from the high-index-contrast interface with optical feedback, which extends optical path length and augments the photon density of states, accelerating multi-beam phase accumulation within TMDCs. By integrating encoders with InGaAs photodetectors, we construct a snapshot spectrometer with remarkable performance, featuring a wavelength accuracy of 0.02 nm, a spectral resolution of 1 nm, and a detection limit below 1 nW. We further demonstrate the application of this spectrometer in material identification, highlighting its versatility for real-world deployment.

This paper proposes a 1×4 low-profile wideband dual-polarized phased array antenna specifically designed for fifth-generation mobile communication technology (5G) millimeter-wave smartphones. It employs a dual-layer stacked square patch to generate multiple resonant points, thereby broadening the antenna's band-width. With a profile height of 0.608 mm (0.049λLow), it achieves coverage of the n257 and n258 frequency bands as specified by the 3rd Generation Partnership Project (3GPP) protocol. Two feeding probes are used to realize vertical and horizontal dual-polarization, and a metal via connecting the lower patch to the ground plane suppresses high-order modal currents on the lower patch, enhancing polarization purity and impedance matching in the lower frequency band. Finally, simulations and fabrication tests are conducted on the antenna. The measured results indicate that the broadside radiating dual-polarized array antenna operates effectively within the frequency range of 24.25-29.50 GHz; the maximum gain in both H-plane and E-plane configurations exceeds 11 dBi, with gains at tested frequency points greater than 10 dBi; it can achieve a scanning beam coverage of ±60°. This phased array antenna shows promising application prospects in 5G millimeter-wave smartphones.

Subarraying offers a promising strategy to reduce the complexity of multi-beam phased arrays. However, designing implementation-friendly subarray configurations with good sidelobe performance remains challenging due to the inherent non-convexity. This letter presents an efficient method for synthesizing physically contiguous multi-beam subarrayed phased arrays. First, a weighted clustering model is formulated based on pattern-matching theory. Second, an adapted K-means algorithm combined with analytical phase weighting is employed to rapidly generate candidate subarrays and perform beamforming. Finally, an efficient search algorithm is developed to identify a low-sidelobe solution. Numerical results demonstrate that the proposed method is versatile across various array types and achieves enhanced sidelobe suppression while maintaining subarray contiguity for practical implementation.

This article presents a fan-out wafer-level package (FOWLP)-based terahertz (THz) quasi-omnidirectional antenna-in-package (AiP) for chip-to-chip (C2C) wireless interconnect in artificial intelligence of things (AIoT). The proposed design integrates key technological advancements, including packaging material characterization, the development and validation of vertical and horizontal interconnect structures, and the quasi-omnidirectional antenna for THz applications. A novel copper-stacked substrate-integrated waveguide (CS-SIW) multimode cavity, developed using FOWLP, enables broadband, high-precision dielectric characterization across the 150–270-GHz range, allowing accurate extraction of the dielectric constant and loss tangent. Additionally, a grounded coplanar waveguide (GCPW) with a back-to-back transition validates the process performance in the THz band. The quasi-omnidirectional antenna, implemented on the redistribution layer (RDL), operates within the 215–230-GHz band, achieving a low profile of $0.0036\lambda _{\mathbf {0}}$ at 220 GHz and a peak gain of 2.13 dBi. The simulated and measured results demonstrate strong agreement, confirming the module’s performance in terms of −10-dB impedance bandwidth and consistent radiation patterns. This work provides a promising solution for integrating compact, efficient THz AiP into future C2C wireless interconnect in AIoT.

A novel reconfigurable reflectarray (RRA) with angularly stable scanning gain is proposed in this letter based on the principle of antenna reciprocity. This RRA element consists of a ME dipole antenna and a reflective phase shifter integrated with PIN diodes. Due to the angular stable gain of the ME dipole antenna, the RRA element demonstrates good angular stability. In addition, the RRA, adopting a 16×16 array configuration, achieves a beam scanning range of 70° with a 1dB loss within a 40° scanning range. To mitigate the control complexity of the system, a cascaded shifter control scheme is employed, which simplifies the design of the control circuitry. Experimental verification shows that both the wide-angle scanning capability and the scanning gain stability of the system are highly consistent with the simulation results.