Integrated Optoelectronics (Norway)

We fabricated an optimized double nested anti-resonant nodeless fiber (DNANF) for the visualization of poled domain in periodically poled lithium niobate (PPLN). Through optimized structural and fabrication processes, the optimized DNANF achieved a low transmission loss below 3×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> dB/m at 920-1040 nm. The femtosecond laser with a central wavelength of 1034 nm and a repetition rate of 34 MHz was coupled with the optimized DNANF in second-harmonic generation (SHG) imaging system. It can be used to achieve a high-resolution three-dimensional (3D) imaging of poled domains in PPLN, with a field of view (FOV) of 102.4 μm × 102.4 μm and a lateral resolution of 0.815 μm. In future, this DNANF will provide a stable, high-efficiency, and simple method of femtosecond laser propagation for the 3D precision characterization of poled domains in materials such as ferroelectric crystals and liquid crystals, as well as two-photon neuroimaging.

Na4MnV(PO4)3 stands as a promising cathode material for sodium-ion batteries owing to its low cost and multiple redox potentials. However, challenges such as drastic local distortion, irreversible phase evolution, and transition metal dissolution in multielectron redox processes, coupled with intrinsic low electronic conductivity jointly trouble its practical deployment. Herein, the Ti4+ with a d0 arrangement is employed to customize the TM-O bonds to eliminate the structural distortion in Na4MnV(PO4)3. The coupling coordination effect of multiple transition metals activates the Mn4+/3+ redox while reinforcing structural stability in over two-electron redox processes, enabling the Na3.1(MnV)0.7Ti0.6(PO4)3 (MnVTi) cathode to realize a 2.4 e- reversible transfer and deliver a specific capacity of 138.4 mAh g-1. Experimental and theoretical calculations reveal that robust TM-O bonds with dynamic covalent chemistry, particularly the strong covalent Ti-O bonds, unlock ultrafast and durable cycling performance (78.4% capacity retention after 10,000 cycles at 20 C). Furthermore, the enhanced electronic conductivity and reaction kinetics contribute to the exceptional rate performance (74.2 mAh g-1 at 50 C), fast-charging capability (1.77 min to reach 80% SOC), and fabulous all-weather adaptability (-40 to 50 °C). This work establishes a universal design paradigm for high-performance Mn-based polyanion cathodes through d0-metal coupling mediated by dynamic covalent chemistry.

All-solid-state lithium batteries (ASSLBs) are promising next-generation energy storage systems due to their superior safety. While low-cost Li2ZrCl6 is a candidate halide solid electrolyte, its ionic conductivity remains modest (0.33 mS cm–1). Herein, we report a highly conductive amorphous halide solid electrolyte (1.64 mS cm–1), synthesized using high-energy Li2CO3 as a precursor to replace conventional Li2O. This approach enhances reaction efficiency and reduces cost. The resulting Li2ZrOCl4 (LZOC) structure facilitates Li+ migration, as confirmed by experimental and theoretical results. ASSLBs incorporating the LZOC electrolyte with a Li–In anode and uncoated LiCoO2 (LCO) cathode demonstrate excellent cycling stability (97% capacity retention after 200 cycles at 1 C) and high-rate capability (over 70 mAh g–1 at 2 C). This work establishes the use of low-cost Li2CO3 as a practical strategy for developing high-performance, cost-effective ASSLBs.

Vectorial Doppler metrology exploits spatially varying polarization structures to enable direction-sensitive angular velocimetry, offering capabilities beyond those of scalar Doppler schemes. However, applying such vectorial strategies within nonlinear detection frameworks remains challenging, as conventional frequency-conversion processes are inherently polarization-dependent and tend to distort the vectorial topology that encodes directional Doppler information. In this work, we overcome this fundamental limitation by introducing a spatial-polarization-independent upconversion scheme that preserves the full vectorial structure of rotational Doppler signals. This allows for infrared Doppler polarization signals to be conformally translated into the visible domain while retaining their directional sensitivity. Within this preserved vectorial framework, we realize direction-resolved rotational velocimetry through two complementary detection approaches: a commonly employed polarization differential detection method and a newly proposed polarization heterodyne detection scheme that provides a compact and robust time–frequency route to retrieving the rotation direction. These results establish a practical pathway for vectorial Doppler sensing under nonlinear frequency conversion and highlight the broader utility of multidimensional optical degrees of freedom for robust, high-fidelity multiparameter measurement.

Two-dimensional (2D) material heterostructure technology has been widely applied in numerous photodetectors due to its efficient light–matter interaction and versatile device construction. However, less attention has been paid to the coordinated optimization of photogenerated carrier dynamics, spanning generation, separation, and transportation procedures, which requires comprehensive consideration from both optical and electrical aspects. Here, we designed and fabricated a six-electrode ZnTe/Bi2O2Se heterostructure photodetector, which enables a direct comparison of the performance of three material configurations (ZnTe, Bi2O2Se, and the heterostructure) within a single device. The ZnTe nanoribbon, with its direct-bandgap structure, exhibits efficient light absorption and photogenerated carrier production. When combined with the high carrier mobility of Bi2O2Se 2D nanosheets, the heterostructure region demonstrates superior photoresponse under weak light illumination compared to the individual material regions; the responsivity reaches 107.6 A/W, more than twice that of the Bi2O2Se region. The stable photoresponse of the heterostructure region under low light intensity and low bias voltage makes it suitable for optical imaging applications. This work highlights the importance of heterostructure technology and device architecture design, providing insights for achieving high-performance photodetectors.

Abstract Information and communication technology (ICT) has advanced significantly in the modern era, and the majority of smart technology utilized in smart cities are Internet of things (IoT) based. Hybrid passive optical networks (PON) consist of wavelength division multiplexing (WDM) and time division multiplexing (TDM) are of the most encouraging and widely utilized technologies in optical distribution networks (ODN) required for security, encryption data and bandwidth. The security of the mystery/private cryptographic key is crucial to the encryption process’s ability to secure data. Any strong encryption algorithm would be compromised by poor key management. In order to enhance the physical security, so as to protect the secret data during transmission across the channel and to ensure a secure exchange of the encryption key between the transmitter and the recipient, a hybrid system that incorporates cryptography, steganography, and key hiding techniques has been employed. To the best of our knowledge, Opti-System software with python devices combine to create a secure WDM/TDM-PON system depending on the Hill Group cipher and ITU-T G.989.2 standards. Simulation studies indicate that, a bidirectional fiber distance with a splitting ratio 1:64 and a symmetrical 40 Gbps can be accomplished successfully out at 60 km. The least amount of acceptable receiver sensitivity is −28.1 dBm for uplink (U/S) and −23.7 dBm for downlink (D/S).

Undulatory movement is widely observed in the animal kingdom, from snakes and earthworms to microorganisms. Mimicking such deformation is important in soft robotics in terms of locomotion control and navigation efficiency. However, realizing such motion at miniature scales in fluid environments remains difficult for soft actuators. Here, we present light-controlled undulatory motion inspired by C. elegans, realized in a millimeter-scale liquid crystal elastomer (LCE) fiber actuator under water. We use the sequential excitation of four laser beams to generate bimorphic actuation between two segments of the LCE, with a 45-degree phase delay between two consequent deformation phases. The actuator demonstrates stable figure-eight-like trajectories and directional steering through laser power modulation. Furthermore, the actuation performance scales with fiber length, providing amplitude tuning and demonstrating programmable control of locomotion.