Complete-mapping mobile optical communication network.

Light serves as an efficient information carrier for communication across air, land, and underwater environments due to its diverse propagation behaviors. Here, we establish a complete-mapping mobile all-light communication network that merges wired modes with wireless moving and fixed nodes, utilizing light sources of different wavelengths. To address alignment challenges in mobile bidirectional light transmission, a visual tracking module and a full-duplex light communication module are packaged together and fixed on a three-axis gimbal stabilizer.

Solution-processable polymer membranes with hydrophilic subnanometre pores for sustainable lithium extraction.

Membrane-based separation processes hold great promise for sustainable extraction of lithium from brines for the rapidly expanding electric vehicle industry and renewable energy storage. However, it remains challenging to develop high-selectivity membranes that can be upscaled for industrial processes. Here we report solution-processable polymer membranes with subnanometre pores with excellent ion separation selectivity in electrodialysis processes for lithium extraction.

Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities.

Human health is being threatened by environmental microplastic (MP) pollution. MPs were detected in the bloodstream and multiple tissues of humans, disrupting the regular physiological processes of organs. Nanoscale plastics can breach the blood-brain barrier, leading to neurotoxic effects.

Programmable photonic circuits.

The growing maturity of integrated photonic technology makes it possible to build increasingly large and complex photonic circuits on the surface of a chip. Today, most of these circuits are designed for a specific application, but the increase in complexity has introduced a generation of photonic circuits that can be programmed using software for a wide variety of functions through a mesh of on-chip waveguides, tunable beam couplers and optical phase shifters. Here we discuss the state of this emerging technology, including recent developments in photonic building blocks and circuit architectures, as well as electronic control and programming strategies.

Multi-channel surface plasmon resonance biosensor using prism-based wavelength interrogation.

A portable multi-channel surface plasmon resonance (SPR) biosensor device using prism-based wavelength interrogation is presented. LEDs were adopted as a simple and inexpensive light source, providing a stable spectrum bandwidth for the SPR system. The parallel light was obtained by a collimated unit and illuminated on the sensing chip at a specific angle.

Unscrambling light-automatically undoing strong mixing between modes.

Propagation of light beams through scattering or multimode systems may lead to the randomization of the spatial coherence of the light. Although information is not lost, its recovery requires a coherent interferometric reconstruction of the original signals, which have been scrambled into the modes of the scattering system. Here we show that we can automatically unscramble optical beams that have been arbitrarily mixed in a multimode waveguide, undoing the scattering and mixing between the spatial modes through a mesh of silicon photonics tuneable beam splitters.

Antarctic and global climate history viewed from ice cores.

A growing network of ice cores reveals the past 800,000 years of Antarctic climate and atmospheric composition. The data show tight links among greenhouse gases, aerosols and global climate on many timescales, demonstrate connections between Antarctica and distant locations, and reveal the extraordinary differences between the composition of our present atmosphere and its natural range of variability as revealed in the ice core record. Further coring in extremely challenging locations is now being planned, with the goal of finding older ice and resolving the mechanisms underlying the shift of glacial cycles from 40,000-year to 100,000-year cycles about a million years ago, one of the great mysteries of climate science.

Imaging through a projection screen using bi-stable switchable diffusive photon sieves.

We designed and demonstrated a liquid crystal (LC) photon sieve (PS) device which can be integrated on a conventional diffusive projection screen and switched to record images. The device fabrication method and assembly of it by using Smectic A (SmA) LC material is also presented. In the PS state, the device comprises diffusive elements, which simultaneously allow to image the scene in front of the device on a camera sensor behind itself and display another image projected onto the device.

Phase-stable Doppler OCT at 19 MHz using a stretched-pulse mode-locked laser.

We present a swept-wavelength optical coherence tomography (OCT) system with a 19 MHz laser source and electronic phase-locking of the source, acquisition clock, and beam scanning mirrors. The laser is based on stretched-pulse active mode-locking using an electro-optic modulator. Beam scanning in the fast axis uses a resonant micro-electromechanical systems (MEMS) -based mirror at ~23.

Improvement of disturbing color effects depending on the axial color of an automotive headlamp lens.

Light-emitting diodes (LEDs) are causing big changes in the automotive lighting field. Optical systems with LEDs can use a plastic lens, which means almost all shapes can be made through plastic injection molding. Already, some car manufacturers are adopting this technology in their designs to express their own identities to customers.

Universal modal radiation laws for all thermal emitters.

We derive four laws relating the absorptivity and emissivity of thermal emitters. Unlike the original Kirchhoff radiation law derivations, these derivations include diffraction, and so are valid also for small objects, and can also cover nonreciprocal objects. The proofs exploit two recent approaches.

60 dB high-extinction auto-configured Mach-Zehnder interferometer.

Imperfections in integrated photonics manufacturing have a detrimental effect on the maximal achievable visibility in interferometric architectures. These limits have profound implications for further technological developments in photonics and in particular for quantum photonic technologies. Active optimization approaches, together with reconfigurable photonics, have been proposed as a solution to overcome this.

Devil's lens optical tweezers.

We demonstrate an optical tweezers using a laser beam on which is imprinted a focusing phase profile generated by a Devil's staircase fractal structure (Cantor set). We show that a beam shaped in this way is capable of stably trapping a variety of micron- and submicron-sized particles and calibrate the optical trap as a function of the control parameters of the fractal structure, and explain the observed variation as arising from radiation pressure exerted by unfocused parts of the beam in the region of the optical trap. Experimental results are complemented by calculation of the structure of the focus in the regime of high numerical aperture.

High-speed terahertz reflection three-dimensional imaging using beam steering.

High-speed terahertz (THz) reflection three-dimensional (3D) imaging is demonstrated using electronically-controlled optical sampling (ECOPS) and beam steering. ECOPS measurement is used for scanning an axial range of 7.8 mm in free space at 1 kHz scan rate while a transverse range of 100 × 100 mm(2) is scanned using beam steering instead of moving an imaging target.

Observational determination of surface radiative forcing by CO2 from 2000 to 2010.

The climatic impact of CO2 and other greenhouse gases is usually quantified in terms of radiative forcing, calculated as the difference between estimates of the Earth's radiation field from pre-industrial and present-day concentrations of these gases. Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annual-mean radiative forcing at the tropopause of 1.82 ± 0.

4D tracking of clinical seminal samples for quantitative characterization of motility parameters.

In this paper we investigate the use of a digital holographic microscope, with partial spatial coherent illumination, for the automated detection and tracking of spermatozoa. This in vitro technique for the analysis of quantitative parameters is useful for assessment of semen quality. In fact, thanks to the capabilities of digital holography, the developed algorithm allows us to resolve in-focus amplitude and phase maps of the cells under study, independently of focal plane of the sample image.

Reconfigurable add-drop multiplexer for spatial modes.

We show how a spatial mode can be extracted from a light beam, leaving the other orthogonal modes undisturbed, and allowing a new signal to be retransmitted on that mode. The method is self-aligning, avoids fundamental splitting losses, and uses only local feedback loops on controllable beam splitters and phase shifters. It could be implemented with Mach-Zehnder interferometers in planar optics.

Self-aligning universal beam coupler.

We propose a device that can take an arbitrary monochromatic input beam and, automatically and without any calculations, couple it into a single-mode guide or beam. Simple feedback loops from detectors to modulator elements allow the device to adapt to any specific input beam form. Potential applications include automatic compensation for misalignment and defocusing of an input beam, coupling of complex modes or multiple beams from fibers or free space to single-mode guides, and retaining coupling to a moving source.

How complicated must an optical component be?

We analyze how complicated a linear optical component has to be if it is to perform one of a range of functions. Specifically, we devise an approach to evaluating the number of real parameters that must be specified in the device design or fabrication, based on the singular value decomposition of the linear operator that describes the device. This approach can be used for essentially any linear device, including space-, frequency-, or time-dependent systems, in optics, or in other linear wave problems.

All linear optical devices are mode converters.

We show that every linear optical component can be completely described as a device that converts one set of orthogonal input modes, one by one, to a matching set of orthogonal output modes. This result holds for any linear optical structure with any specific variation in space and/or time of its structure. There are therefore preferred orthogonal "mode converter" basis sets of input and output functions for describing any linear optical device, in terms of which the device can be described by a simple diagonal operator.

Spectral discomfort glare sensitivity investigations.

The main concern of car headlamp manufacturers is to provide better visibility. Unfortunately, by increasing the luminous intensity of the headlamp, the risk of increasing discomfort glare for the other road users increases. One possibility to increase visibility and decrease glare could be the selection of a spectral power distribution for the headlamp such that it emits in wavelength regions (if such wavelengths exist) where luminous sensitivity is high, and glare sensitivity is low.

Communicating with waves between volumes: evaluating orthogonal spatial channels and limits on coupling strengths.

A rigorous method for finding the best-connected orthogonal communication channels, modes, or degrees of freedom for scalar waves between two volumes of arbitrary shape and position is derived explicitly without assuming planar surfaces or paraxial approximations. The communication channels are the solutions of two eigenvalue problems and are identical to the cavity modes of a double phase-conjugate resonator. A sum rule for the connection strengths is also derived, the sum being a simple volume integral.

Spatial channels for communicating with waves between volumes.

I show that there is an exact, complete method for finding the orthogonal spatial channels, or communications modes, between two arbitrary volumes, and the associated connection strengths, for the case of scalar waves. I also show that the sum of the squared connection strengths is given exactly by a simple volume integral. The method is illustrated by a calculation for a particular extreme pair of volumes, and the communications modes are interpreted physically as the modes of a double phase-conjugate resonator.

Wavelength dependence of intraocular straylight.

Wavelength dependence of retinal straylight has been a mystery since Stiles in 1929 [Stiles,W.S., 1929.