Hybrid silicon-organic integrated photonic circuits for broadband terahertz field-resolved detection

Terahertz (THz) radiation occupies a spectral region between 100 GHz and 10 THz of growing interest for applications in spectroscopy, imaging, and high-speed communications. In free-space implementations, THz generation and detection are commonly achieved using nonlinear crystals through optical rectification and electro-optic sampling, photoconductive antennas based on III-V semiconductors, or more recently spintronic emitters. While these approaches provide large bandwidth and high fidelity, they typically rely on bulky optical setups, precise alignment, and relatively high optical powers. Integrated photonic platforms offer a promising direction to overcome these limitations by combining photonic circuits, nonlinear materials, and microstrip antennas on a single chip. Integrated solutions based on thin-film lithium niobate or III-V photonic platforms have already demonstrated on-chip THz generation and detection, yet challenges remain in terms of scalability, footprint, and compatibility with large-scale fabrication. In this manuscript, we report the development of hybrid silicon-organic photonic devices for field resolved terahertz detection based on electro-optic sampling. Profiting from the maturity, stability and low-power operation offered by silicon-on-insulator platforms, the detectors integrate silicon waveguides, plasmonic interaction regions, and metallic antennas with highly nonlinear organic electro-optic materials, enabling both broadband and spectrally selective operation within a compact footprint. After the development of an in-house fabrication process flow, we demonstrate control over the temporal and spectral response of the detectors by tailoring the antenna geometry, achieving both broadband detection up to 2.5 THz and narrowband operation at selected resonance frequencies with peak dynamic ranges of 60 dB, in all cases with optical powers below 100 nW. The stability of the devices is also investigated under different illumination and alignment conditions, showing robust performance in practical and non-ideal operating regimes. In addition, we explore an alternative DC-assisted approach to activate the nonlinear response of the organic material without a dedicated poling step, demonstrating the feasibility of reconfigurable detection, although with reduced efficiency and limitations related to device stability. We further implement a balanced detection scheme that exploits the interferometric architecture of the photonic circuit to enhance the detected modulation amplitude and dynamic range while preserving the intrinsic spectral response, with maximum induced modulations reaching 4%. Beyond detection, we investigate the versatility of the fabrication platform by adapting the process flow to co-integrate spintronic emitters and by exploring the fabrication of molecular glass waveguides formed directly from organic electro-optic materials. These preliminary results highlight the potential of hybrid silicon-organic technolog