National Defense Institute

Conventional waveguide superlattices rely on theoretical physics models with manual refractive index tuning to control light propagation, yielding limited design freedom and poor scalability. Here, we propose a universal design framework using inverse-designed waveguide superlattices and demonstrate a 1 × 2 polarization-insensitive power splitter. The designed device exhibits an ultra-broad bandwidth (1450-1650 nm) with insertion losses below 0.26 dB for both TE0 and TM0 modes. Fabricated via a CMOS-compatible process, the splitter experimentally achieves insertion loss <0.31 dB and power imbalance <0.24 dB over 1485-1635 nm. This design strategy is further extended to a 1 × 4 splitter with excellent polarization insensitivity and broadband performance, thus confirming the universality of the proposed superlattice approach and providing a novel, to the best of our knowledge, paradigm for developing next-generation photonic devices.

Abstract Wireless communications feature high data rates, low latency, and ultra-reliable characteristics for future communications. It necessarily requires highly efficient, programmable, and multifunctional arrays in both spatial, temporal, and wave domains, thus compensating the path loss, extending spectral links, and enlarging spatial coverage. The current state of the art presents several challenges, including narrow bandwidth, limited efficiency, remarkable loss, and constrained coverage in full space with unconnected transmission-reflection-integrated links. Here, harvesting the optoelectronic-modulated arrays integrated with multi-wavelength response resonators, we report broadband single-layer modulation devices with the picosecond modulation speed via pulsed light, the maximum modulation efficiency that approaches the fundamental modulation limit, and space-time synchronous link between the transmission and reflection. It could modulate the signals in the picosecond level by pump light with low fluence of 100 μJ/cm2 and tailor the wavefront covering a large bandwidth. Two prototypes are fabricated with gradient and holographic phase distributions, where the 168° field-of-view for beam steering and nearly 100% similarity for holograms are realized, respectively. This novel scheme of arrays is promising to advance in wireless communication, and inspires more all-optical innovations in the field of nanophotonics and semiconductors.

Controllable manipulation of propagating graphene plasmons (GPs) has important significance in the application of nanophotonic and optoelectronic technologies. In this paper, a simple graphene-semiconductor hybrid structure is proposed, in which unidirectional emission of propagating GPs can be achieved and controlled under circularly polarized light illumination. The impact of the distance between the nanorod and graphene and the radius of the nanorod on the excitation efficiency of GPs, as well as the impact on the unidirectional ratio are theoretically calculated in detail. The results show that considering both the unidirectional ratio and the excitation efficiency of GPs, the radius of the nanorod can be selected between 15 and 50 nm. It is also found that the maximum unidirectional ratio η of GPs does not depend on the different distances between the nanorod and graphene. This study not only provides optimized parameters for further experimental implementation, but also offers theoretical support for nanoscale information transmission and processing.

An autoencoder-residual (AE-Res) network is designated to assist the linearization of the wideband photonic scanning channelized receiver. It is capable of adaptively suppressing spurious distortions over multiple octaves of signal bandwidth, obviating the need for calculating the multifactorial nonlinear transfer functions. Proof-of-concept experiments indicate that the improvement of the third-order spur-free dynamic range (SFDR2/3) is 17.44 dB. Moreover, the results for real wireless communication signals demonstrate that the improvement of the spurious suppression ratio (SSR) is 39.69 dB and the reduction of the noise floor is ∼10 dB.

This paper proposes a forecasting methodology that investigates a set of different sparse structures for the vector autoregression (VAR) model using the Ivanov‐based least absolute shrinkage and selection operator (LASSO) framework. The variant auxiliary problem principle method is used to solve the various Ivanov‐based LASSO‐VAR variants, which is supported by parallel computing with simple closed‐form iteration and linear convergence rate. A test case with ten crude oil spot prices is used to demonstrate the improvement in forecasting skills gained from exploring sparse structures. The proposed method outperformed the conventional vector autoregressive model.

Battlefield medical advances, improvements in protective equipment, and progress in surgical reconstruction and rehabilitation have led to questions about when to emphasize limb salvage over other treatment options — such as amputation — for individuals with severe blast-related limb injuries. These conference proceedings summarize findings, conclusions, and recommendations of an expert-led meeting held in March 2019 that addressed such questions.

The state of development of the information society of a particular country can have a great influence on the outcome of a cyberwarfare in which it is involved. This influence, in the possible outcome of a war of this type, can be positive or negative. In addition, contrary to what might initially be thought, a low development of the information society can be advantageous to obtain a victory, if one strictly considers the scenario of cyberwar and the countries in confrontation. This way we analyze this influence and relationship between the information society and cyberwarfare in the scope of security and defense. We designate this dependency as Cybernetic Dependency Capacity. This dependence is a very important factor in the results of cyberwarfare actions and can be positive or negative for both technologically developed and less-developed countries. For these reasons, the destiny of any country, within the scope of a cyberwar, is very influenced by the dependence of this country of their information society. As a major development of the IT society in one country will not make it theoretically victorious in a cyberwarfare with a country less IT developed. This fact, which is apparently paradoxical, is because the larger information society of a country is more informatics systems have to exist. Then, if much more informatics systems exist, more cyber-doors are open for cyber-attacks, because the probability of these systems will be unprotected, from the point of view of cyber-attacks, increases with the growth in the number of computers systems. For the same reason, the countries with less dependence on the information society do not have this cyber-permeability and may be more cyber-resilient. In the limit, theoretically, the least dependent cyber-country can be the winner and the most dependent and as such, technologically more developed, be the loser in a cyberwar between the two. These scenarios are also applicable to non-states and terrorist organizations and for these reasons should be analyzed and considered in the definition of the cyber-defense policies of any country, namely in the factors like a Cybernetic Attack Capacity and a Cybernetic Dependency Capacity.

The terahertz dynamics of water nanodroplets confined in phospholipid reverse micelles have been developed as a probe to explore the interactions of metal ions with lipid membrane interfaces. The terahertz absorption coefficients of reverse micelles vary greatly with different Cu2+ concentrations and with different headgroups. The results proved that the metal ion effects on water dynamics near a membrane surface can be detected via terahertz spectroscopy, thus providing a novel tool for investigating ion-lipid interactions.