Inverse design for waveguide dispersion with a differentiable mode solver.

Inverse design of optical components based on adjoint sensitivity analysis has the potential to address the most challenging photonic engineering problems. However, existing inverse design tools based on finite-difference-time-domain (FDTD) models are poorly suited for optimizing waveguide modes for adiabatic transformation or perturbative coupling, which lies at the heart of many important photonic devices. Among these, dispersion engineering of optical waveguides is especially challenging in ultrafast and nonlinear optical applications involving broad optical bandwidths and frequency-dependent anisotropic dielectric material response.

Critical evaluation of non-uniform optical phased arrays for real-world beam-steering applications.

Optical phased arrays (OPAs) are a promising technology for the realization of fast and compact non-mechanical optical beam steering. While many experimental demonstrations of integrated OPAs exist in the literature, it is challenging to evaluate their suitability for real-world applications due to the lack of system-level performance requirements. Here, we derive such performance requirements for two of the most promising OPA applications - namely free space optical communications (FSOC) and light detection and ranging (LIDAR) - and show that traditional uniformly spaced OPA architectures likely cannot reach the required performance.

Precise and High-Throughput Delivery of Micronutrients in Plants Enabled by Pollen-Inspired Spiny and Biodegradable Microcapsules.

Decarbonizing food production and mitigating agriculture's environmental impact require new technologies for precise delivery of fertilizers and pesticides to plants. The cuticle, a waxy barrier that protects the surface of leaves, causes 60%-90% runoff of fertilizers and pesticides, leading to the wastage of intensive resources, soil depletion, and water bodies pollution. Solutions to mitigate runoff include adding chemicals (e.

A high-density microfluidic bioreactor for the automated manufacturing of CAR T cells.

The manufacturing of autologous chimaeric antigen receptor (CAR) T cells largely relies either on fed-batch and manual processes that often lack environmental monitoring and control or on bioreactors that cannot be easily scaled out to meet patient demands. Here we show that human primary T cells can be activated, transduced and expanded to high densities in a 2 ml automated closed-system microfluidic bioreactor to produce viable anti-CD19 CAR T cells (specifically, more than 60 million CAR T cells from donor cells derived from patients with lymphoma and more than 200 million CAR T cells from healthy donors). The in vitro secretion of cytokines, the short-term cytotoxic activity and the long-term persistence and proliferation of the cell products, as well as their in vivo anti-leukaemic activity, were comparable to those of T cells produced in a gas-permeable well.

Harnessing Raman spectroscopy for the analysis of plant diversity.

Here, we explore the application of Raman spectroscopy for the assessment of plant biodiversity. Raman spectra from 11 vascular plant species commonly found in forest ecosystems, specifically angiosperms (both monocots and eudicots) and pteridophytes (ferns), were acquired in vivo and in situ using a Raman leaf-clip. We achieved an overall accuracy of 91% for correct classification of a species within a plant group and identified lignin Raman spectral features as a useful discriminator for classification.

Effects of Storage Temperatures on Nitrogen Assimilation and Remobilization during Post-Harvest Senescence of Pak Choi.

In the agricultural industry, the post-harvest leafy vegetable quality and shelf life significantly influence market value and consumer acceptability. This study examined the effects of different storage temperatures on leaf senescence, nitrogen assimilation, and remobilization in Pak Choi ( subsp. ).

Nanosecond pulsed CMOS LED for all-silicon time-of-flight ranging.

Light detection and ranging (LIDAR) is a widely used technique for measuring distance. With recent advancements in integrated photonics, there is a growing interest in miniaturizing LIDAR systems through on-chip photonic devices, but a LIDAR light source compatible with current integrated circuit technology remains elusive. In this letter, we report a pulsed CMOS LED based on native Si, which spectrally overlaps with Si detectors' responsivity and can produce optical pulses as short as 1.

On-site growth of perovskite nanocrystal arrays for integrated nanodevices.

Despite remarkable progress in the development of halide perovskite materials and devices, their integration into nanoscale optoelectronics has been hindered by a lack of control over nanoscale patterning. Owing to their tendency to degrade rapidly, perovskites suffer from chemical incompatibility with conventional lithographic processes. Here, we present an alternative, bottom-up approach for precise and scalable formation of perovskite nanocrystal arrays with deterministic control over size, number, and position.

A sub-wavelength Si LED integrated in a CMOS platform.

A nanoscale on-chip light source with high intensity is desired for various applications in integrated photonics systems. However, it is challenging to realize such an emitter using materials and fabrication processes compatible with the standard integrated circuit technology. In this letter, we report an electrically driven Si light-emitting diode with sub-wavelength emission area fabricated in an open-foundry microelectronics complementary metal-oxide-semiconductor platform.

Computational polarized Raman microscopy on sub-surface nanostructures with sub-diffraction-limit resolution.

Raman microscopy with resolution below the diffraction limit is demonstrated on sub-surface nanostructures. Unlike most other modalities for nanoscale measurements, our approach is able to image nanostructures buried several microns below the sample surface while still extracting details about the chemistry, strain, and temperature of the nanostructures. In this work, we demonstrate that combining polarized Raman microscopy adjusted to optimize edge enhancement effects and nanostructure contrast with fast computational deconvolution methods can improve the spatial resolution while preserving the flexibility of Raman microscopy.

Rapid Detection and Quantification of Plant Innate Immunity Response Using Raman Spectroscopy.

We have developed a rapid Raman spectroscopy-based method for the detection and quantification of early innate immunity responses in Arabidopsis and Choy Sum plants. Arabidopsis plants challenged with flg22 and elf18 elicitors could be differentiated from mock-treated plants by their Raman spectral fingerprints. From the difference Raman spectrum and the value of at each Raman shift, we derived the Elicitor Response Index (ERI) as a quantitative measure of the response whereby a higher ERI value indicates a more significant elicitor-induced immune response.

Low-power swept-source Raman spectroscopy.

'Molecular fingerprinting' with Raman spectroscopy can address important problems-from ensuring our food safety, detecting dangerous substances, to supporting disease diagnosis and management. However, the broad adoption of Raman spectroscopy demands low-cost, portable instruments that are sensitive and use lasers that are safe for human eye and skin. This is currently not possible with existing Raman spectroscopy approaches.

Impact of laser frequency noise on high-extinction optical modulation.

In present literature on integrated modulation and filtering, limitations in the extinction ratio are dominantly attributed to a combination of imbalance in interfering wave amplitude, instability of control signals, stray light (e.g., in the cladding), or amplified spontaneous emission from optical amplifiers.

Species-independent analytical tools for next-generation agriculture.

Innovative approaches are urgently required to alleviate the growing pressure on agriculture to meet the rising demand for food. A key challenge for plant biology is to bridge the notable knowledge gap between our detailed understanding of model plants grown under laboratory conditions and the agriculturally important crops cultivated in fields or production facilities. This Perspective highlights the recent development of new analytical tools that are rapid and non-destructive and provide tissue-, cell- or organelle-specific information on living plants in real time, with the potential to extend across multiple species in field applications.

Portable Raman leaf-clip sensor for rapid detection of plant stress.

Precision agriculture requires new technologies for rapid diagnosis of plant stresses, such as nutrient deficiency and drought, before the onset of visible symptoms and subsequent yield loss. Here, we demonstrate a portable Raman probe that clips around a leaf for rapid, in vivo spectral analysis of plant metabolites including carotenoids and nitrates. We use the leaf-clip Raman sensor for early diagnosis of nitrogen deficiency of the model plant Arabidopsis thaliana as well as two important vegetable crops, Pak Choi (Brassica rapa chinensis) and Choy Sum (Brassica rapa var.

Rapid metabolite response in leaf blade and petiole as a marker for shade avoidance syndrome.

Background: Shade avoidance syndrome (SAS) commonly occurs in plants experiencing vegetative shade, causing morphological and physiological changes that are detrimental to plant health and consequently crop yield. As the effects of SAS on plants are irreversible, early detection of SAS in plants is critical for sustainable agriculture. However, conventional methods to assess SAS are restricted to observing for morphological changes and checking the expression of shade-induced genes after homogenization of plant tissues, which makes it difficult to detect SAS early.

Early Diagnosis and Management of Nitrogen Deficiency in Plants Utilizing Raman Spectroscopy.

Nutrient deficiency alters growth and development of crop plants and compromises yield. Real-time non-invasive monitoring of the nutritional status of crops would allow timely applications of fertilizers to optimize for growth and yield at different times of the plant's life cycle. Here, we used Raman spectroscopy to characterize Arabidopsis and two varieties of leafy vegetable crops under nitrogen sufficient and deficient conditions.

Photonic Readout of Superconducting Nanowire Single Photon Counting Detectors.

Scalable, low power, high speed data transfer between cryogenic (0.1-4 K) and room temperature environments is essential for the realization of practical, large-scale systems based on superconducting technologies. A promising approach to overcome the limitations of conventional wire-based readout is the use of optical fiber communication.

Power handling of silicon microring modulators.

Silicon photonic wavelength division multiplexing (WDM) transceivers promise to achieve multi-Tbps data rates for next-generation short-reach optical interconnects. In these systems, microring resonators are important because of their low power consumption and small footprint, two critical factors for large-scale WDM systems. However, their resonant nature and silicon's strong optical nonlinearity give rise to nonlinear effects that can deteriorate the system's performance with optical powers on the order of milliwatts, which can be reached on the transmitter side where a laser is directly coupled into resonant modulators.

Compact and high-precision wavemeters using the Talbot effect and signal processing.

Precise knowledge of a laser's wavelength is crucial for applications from spectroscopy to telecommunications. Here, we present a wavemeter that operates on the Talbot effect. Tone parameter extraction algorithms are used to retrieve the frequency of the periodic signal obtained in the sampled Talbot interferogram.

Publisher Correction: Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip.

In this Letter, owing to an error during the production process, the author affiliations were listed incorrectly. Affiliation number 5 (Colleges of Nanoscale Science and Engineering, State University of New York (SUNY)) was repeated, and affiliation numbers 6-8 were incorrect. In addition, the phrase "two oxide thickness variants" should have been "two gate oxide thickness variants".

Monolithic silicon-photonic platforms in state-of-the-art CMOS SOI processes [Invited].

Integrating photonics with advanced electronics leverages transistor performance, process fidelity and package integration, to enable a new class of systems-on-a-chip for a variety of applications ranging from computing and communications to sensing and imaging. Monolithic silicon photonics is a promising solution to meet the energy efficiency, sensitivity, and cost requirements of these applications. In this review paper, we take a comprehensive view of the performance of the silicon-photonic technologies developed to date for photonic interconnect applications.

Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip.

Electronic and photonic technologies have transformed our lives-from computing and mobile devices, to information technology and the internet. Our future demands in these fields require innovation in each technology separately, but also depend on our ability to harness their complementary physics through integrated solutions. This goal is hindered by the fact that most silicon nanotechnologies-which enable our processors, computer memory, communications chips and image sensors-rely on bulk silicon substrates, a cost-effective solution with an abundant supply chain, but with substantial limitations for the integration of photonic functions.

Optical Detection of Degraded Therapeutic Proteins.

The quality of therapeutic proteins such as hormones, subunit and conjugate vaccines, and antibodies is critical to the safety and efficacy of modern medicine. Identifying malformed proteins at the point-of-care can prevent adverse immune reactions in patients; this is of special concern when there is an insecure supply chain resulting in the delivery of degraded, or even counterfeit, drug product. Identification of degraded protein, for example human growth hormone, is demonstrated by applying automated anomaly detection algorithms.

Precise and diffraction-limited waveguide-to-free-space focusing gratings.

We present the design and characterization of waveguide grating devices that couple visible-wavelength light at λ = 674 nm from single-mode, high index-contrast dielectric waveguides to free-space beams forming micron-scale diffraction-limited spots a designed distance and angle from the grating. With a view to application in spatially-selective optical addressing, and in contrast to previous work on similar devices, deviations from the main Gaussian lobe up to 25 microns from the focus and down to the 5 × 10 level in relative intensity are characterized as well; we show that along one dimension the intensity of these weak sidelobes approaches the limit imposed by diffraction from the finite field extent in the grating region. Additionally, we characterize the polarization purity in the focal region, observing at the center of the focus a low impurity <3 × 10 in relative intensity.