Optical transmission based on dense wavelength-division multiplexing (DWDM) is widely considered a key solution for increasing optical-link capacity. However, the complexity and stringent requirements for optical devices in such systems challenge full integration on a chip. Here, we demonstrate the first monolithic DWDM transmitter chip, built on a thin-film lithium niobate. The chip consists of an easy-to-drive and high-efficiency electro-optical (EO) frequency comb generator for a flat-top multi-wavelength source, a single arrayed waveguide grating for both multiplexing and demultiplexing to ensure no wavelength misalignment, and an EO Mach-Zehnder modulator array. Using a single-wavelength laser as input, the proposed transmitter can deliver a total modulated signal of 1.6 Tbps in eight 100-GHz spacing channels using an intensity-modulation direct-detection scheme. A record high spectral efficiency of 2 bps/Hz was achieved for an integrated DWDM transmission system using optical frequency combs. The energy consumption of the entire system was measured to be 2.76 pJ/bit. This work establishes a scalable route towards a versatile and integrated multi-wavelength data processor for DWDM data transmissions, optical computing, and microwave-photonics.

All-optical nonlinear modulators, capable of femtosecond-scale signal modulation, are pivotal for high-speed data transmission in next-generation space optical communications. However, the inherently weak third-order optical nonlinearity of conventional materials remains a significant bottleneck for efficient nonlinear signal processing. In this work, we unveil the extraordinary third-order nonlinear susceptibility χ⁽³⁾ of atomically thin two-dimensional (2D) indium tin oxide (ITO) films within the 1550-nm telecommunications band. By leveraging quantum confinement effects, these 2D ITO layers form discrete electronic subbands that dramatically enhance intersubband transition dipole moments and thus the optical responses. Experimental measurements reveal a record-high angle-averaged χ⁽³⁾ value of 2.0 × 10^-(14) m²/V², representing an approximately 300-fold enhancement over bulk ITO and surpassing graphene by a factor of five. Furthermore, the 2D ITO films maintain high transparency and possess the potential for ultrafast response speeds inherent to electronic nonlinear processes, making them ideal candidates for compact nonlinear photonic integration. These findings demonstrate that 2D ITO, as a representative example of bandgap-engineered transparent conductive oxides (TCOs), provides a versatile platform for high-performance all-optical switching and signal processing in optical networks.

PIER Photonics is a premier open-access journal launched by The Electromagnetics Academy to serve the rapidly evolving photonics community. Focusing on the frontiers and hot topics, the journal covers six strategic domains: Fundamental Science, Materials and Nanostructures, Integrated Photonic Systems, Healthcare and Life Sciences, Sustainability and Information Technology, and Emerging Frontiers. Built on the PIERS conference legacy, PIER Photonics offers rigorous peer review, rapid publication, and a vibrant platform for transformative photonics research.

Singular optics are commonly explored through scalar or vectorial singularities, whereas matrix-level singularities remain far less developed for wave manipulations. Here, we experimentally demonstrate polarization-addressable singular Jones metasurfaces using reflective plasmonic nanostructures. By engineering polarization conversion in the reflection subspace, the Jones matrix can be driven to a singular condition, mapping an incident polarization eigenstate to a vectorial zero output. The corresponding eigen-polarization can be addressed across the Poincaré sphere by tailoring meta-atom geometries. Encircling the singularity in a two-dimensional parameter space can yield a full 2π topological phase winding, enabling dual-channel meta-holography and vortex generation. Extreme coupling breaking further produces circularly polarized zero-output eigenstates, revealing chiral Jones singularities. These results establish singular Jones metasurfaces as a compact platform for matrix-level singular optics, polarization-selective extinction, topological wavefront shaping, and chiral light-matter interactions.

PIER Photonics is a premier open-access journal launched by The Electromagnetics Academy to serve the rapidly evolving photonics community. Focusing on the frontiers and hot topics, the journal covers six strategic domains: Fundamental Science, Materials and Nanostructures, Integrated Photonic Systems, Healthcare and Life Sciences, Sustainability and Information Technology, and Emerging Frontiers. Built on the PIERS conference legacy, PIER Photonics offers rigorous peer review, rapid publication, and a vibrant platform for transformative photonics research.