This study presents a passive terahertz (THz) optoelectronic beamforming network (OBFN), utilizing optical dispersion components to induce time delays or phase shifts in signals with varying frequency components. Two feasible schemes are compared and analyzed in terms of implementation difficulty. To validate the concept, feasibility experiments are designed and prototype circuits towards photonic integration are proposed. A comparative analysis of THz beamforming schemes was performed, indicating that the proposed OBFN is beneficial for various THz applications with high beam flexibility and energy efficiency.

This study presents a novel technique for generating terahertz (THz) waves with frequency modulation capabilities ranging from linear sweeping to random hopping. Departing from conventional methods that utilize wavelength-tunable lasers to produce optical waves with variable frequency differences, this approach harnesses an optical frequency comb to generate optical wave frequencies at fixed intervals. Crucially, it employs a uniquely configured optical filter with adjustable dual passbands, allowing for the selection of optical beats with frequency variances that are multiples of the comb's interval. These beats are subsequently converted into THz waves using a THz photomixer, aligning the THz frequency with the adjustable interval between the filter's passbands. This innovation significantly enhances the versatility and scope of THz wave frequency modulation, offering substantial potential for advancements in high-speed communication, precision imaging, and spectroscopy.

Photonic integrated circuits (PICs) are crucial in terahertz (THz) technology due to their compact, integrated, efficient, and controllable design. They consolidate multiple active or passive components on a single chip, facilitating lightweight construction and high-speed communication, imaging, and sensing applications. The generic foundry platform using indium phosphide (InP) offers a universal integration platform for THz systems. Optical arrays for THz beamforming can precisely adjust the beam length and integrate both passive and active components, enhancing the THz beamforming performance. Indium phosphide-based photonic integrated circuits (PICs) offer an ideal solution for achieving precise, high-speed, compact, and integrated terahertz (THz) beamforming, addressing a broad spectrum of application needs. This study employs an InPbased multi-project wafer (MPW) platform for designing a 4-channel optical phase array (OPA) aimed at THz beamforming. The platform offers a range of validated optical components that can be utilized to construct intricate circuits, thereby enhancing the reliability of the system implementation. Moreover, the hybrid integration technology developed by Smart Photonics and Fraunhofer HHI allows for quick prototyping, short iteration cycles, and reduced development time and costs.