Orbital angular momentum (OAM) modes have emerged as a promising solution for enhancing the capacity of optical multiplexing systems, leveraging their theoretically unbounded set of orthogonal spatial modes. However, the generation and detection of OAM multiplexing signals are predominantly reliant on bulky optical components within complex optical setups. We introduce a compact solution for OAM information processing using laser-written glass chips, facilitating efficient multiplexing and demultiplexing of multiple OAM information channels. During the multiplexing process, OAM channels are managed via laser-scribed single-mode waveguides within a glass chip, with their modes converted using laser-written holograms on the side wall of the glass chip. The reciprocal process is employed for OAM demultiplexing. Our chips seamlessly interface with commercial optical fibers, ensuring compatibility with existing fiber-optic communication infrastructure. This work not only establishes, to our knowledge, a novel approach for OAM optical multiplexing but also underscores the potential of laser writing technology in advancing photonics and its practical applications in optical communications.

To address the current issues of low reconfigurability, low integration, and high dynamic power consumption in programmable units, this study proposes a novel programmable photonic unit cell, termed MZI-cascaded-ring unit (MCR). The unit functions analogously to an MZI, enabling broadband routing when operating within the free spectral range (FSR) of the embedded resonator, and it transitions into a wavelength-selective mode, leveraging the micro-ring’s resonance to achieve precise amplitude and phase control for narrowband signals while outside the FSR, featuring dual operational regimes. With the implementation of spiral waveguide structures, the design achieves higher integration density and lower dynamic power consumption. Based on the hexagonal mesh extension of such a unit, the programmable photonic processor successfully demonstrates a reconfiguration of large amounts of fundamental functions with tunable performance metrics, including broadband linear operations like optical router and wavelength-selective functionalities like wavelength division multiplexing. This work establishes a new paradigm for programmable photonic integrated circuit design.

By introducing photonic crystals with Dirac point based on valley edge states, we design heterostructure waveguides on the silicon-on-insulator platform, promising waveguides with different widths to operate in the single-mode state. Benefiting from the unidirectional transmission and backscattering-immunity characteristics enabled by the topological property, there is no scattering loss induced by the mode-mismatch at the transition junction between the waveguides with different widths. Therefore, the valley-locked heterostructure waveguide possesses unique width degrees of freedom. We demonstrate it by designing and fabricating waveguides with expanding, shrinking, and Z-type configurations. Thanks to the free transition between waveguides with different widths, an interesting energy convergency is observed, which is represented from the imaging of the enhanced third-harmonic generation of the silicon slab. Consequently, these heterostructure waveguides can be more flexibly integrated with existing on-chip devices and have the potential for high-capacity energy transmission, energy concentration, and field enhancement.

The flexibility and active control of terahertz multi-focal focusing is essential for advancing next-generation terahertz communication systems. Here, we present and experimentally demonstrate a voltage-controlled liquid crystal (LC) integrated terahertz multi-focal metalens capable of dynamically reconfiguring focal configurations. Both simulation and experimental results confirm electrically modulated spatial-spin separation and multi-focal focusing within the 0.44–0.55 THz frequency band, exhibiting single-to-quadruple switching for left-handed circularly polarized (LCP) waves and dual-to-single transitions for right-handed circularly polarized (RCP) waves. The LC cascaded metalens achieves a measured full-width-at-half-maximum (FWHM) of <2.35 mm and a peak focusing efficiency of 70.4%. The normalized total output power of single, two, and four focal points exceeds 85.1%, 54.9%, and 59.3%. The combination of spatial-spin separation and reconfigurable focus modes is expected to significantly increase the capacity and energy efficiency of future terahertz communication systems.

Vector vortex beams (VVBs) have garnered significant attention in fields such as photonics, quantum information processing, and optical manipulation due to their unique optical properties. However, traditional metasurface fabrication methods are often complex and costly, limiting their practical application. This study successfully fabricated an all-dielectric aluminum oxide metasurface capable of achieving longitudinal variation using 3D printing technology. Experimental results demonstrate that this metasurface generates longitudinally varying VVBs at 0.1 THz, with detailed characterization of its longitudinal intensity distribution and vector polarization states. The high consistency between experimental and simulation results validates the effectiveness of 3D printing in metasurface fabrication. The proposed metasurface offers promising applications in optical polarization control and communication, providing, to our knowledge, new insights and technical support for related research.