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Industry 4.0 (or 4th industrial revolution) facilitates horizontal and vertical digital information flow along value chains up to the end-customer and is highly relevant in a broad variety of industries. Augmented reality (AR) is a key technology in Industry 4.0, which connects the virtual and real-world environments using such digital information flows. In doing so, the technology relies upon the systems that includes hardware and software components. Particularly, optics and photonics are of much importance in the display and processing of information in these systems. However, a particular challenge is that the AR-based systems have not been adopted in the industry as much as other technologies even after several decades of their existence. Based on review of academic literature, an industrial survey and experiments conducted in the industry, this article aims to identify success factors and challenges of AR systems and metrics of photonic components that can form the basis of an AR* framework for photonics-based system design for future research. [ABSTRACT FROM AUTHOR]

Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) shows great potential for forest height retrieval. However, there are abundant noise photons in the ICESat-2 data, which make the accurate extraction of global forest heights challenging. In this letter, a novel algorithm based on the clustering method of ordering points to identify the clustering structure (OPTICS) was proposed to remove noise photons. First, we modified the circular shape of the search area in the OPTICS algorithm to an elliptical shape. Second, a distance ordering of all photons was generated using the modified OPTICS algorithm. Finally, signal photons were effectively detected using distance thresholds set by the Otsu method. To evaluate the algorithm performance, both the simulated and real ICESat-2 data were applied to our proposed algorithm. In addition, we compared our algorithm with another noise removal algorithm based on the modified density-based spatial clustering of applications with noise (DBSCAN). The results show that our algorithm works well in distinguishing the signal and noise photons as indicated by high F values. Compared with the modified DBSCAN, our algorithm performs better in filtering out noise photons regardless of the simulated or real ICESat-2 data sets. In addition, the results also indicate that our algorithm is robust because it is insensitive to the clustering parameters. Overall, the new proposed algorithm is effective for removing noise photons in the ICESat-2 data. [ABSTRACT FROM AUTHOR]

Contribution: A hybrid approach involving reduced lecture content with project-based learning (PBL) was introduced to a standalone course in optics at an engineering school not specialized in this area, with promising results. Background: At most schools, optics is an elective “niche” area involving a single senior course. This presents challenges, since the topic has breadth and depth, leaving little time for application projects. Yet, seniors want future applicability. After many years, the instructor questioned his “broad-brush” approach involving many topics with limited application, especially given the role of optics and photonics in technology leadership. A literature search uncovered recent use of project-based methods for optics in K–12 and community colleges but little use in U.S. universities, suggesting an opportunity. Intended Outcomes: The authors intended that achievement and valuation by students would be greater with authentic projects and less content. Application Design: Therefore, an approach that concentrated content and project work on light’s dualistic nature in a mathematically rigorous manner was taken. With reduced content, class time was available for PBL, whereby the problem motivated the content. For light’s wave nature, five lecture weeks were followed by a project simulating the propagation of light. For the particle nature, a circuit design project to implement analog electronic circuits during class occurred after five lecture weeks. Findings: Student interviews and instructor perspectives on impacts of learning, career preparation, graduate school interest, and in-class engagement uncovered encouraging results. A direct assessment showed significantly higher homework scores with the course changes. [ABSTRACT FROM AUTHOR]

Disordered optical fibers show novel waveguiding properties, enabled by the transverse Anderson localization of light, and are used for image transport. The strong transverse scattering from the transversely disordered refractive index structure results in transversely confined modes that can freely propagate in the longitudinal direction. In some sense, an Anderson localization disordered fiber behave like a large-core multimode optical fiber, with the advantage that most modes are highly localized in the transverse plane, so any point in the cross section of the fiber can be used for localized beam transport. This property has been used for high-quality transportation of intensity patterns and images in these optical fibers. This review covers the basics and the history of the transverse Anderson localization in disordered optical fibers and captures the recent progress in imaging applications using these optical fibers. [ABSTRACT FROM AUTHOR]

Here, we experimentally demonstrate a faithful single-photon qubits transmission using error-rejecting coding, resorting to neither ancillary photons nor entangled photon resources. Using unbalanced polarization interferometer, the polarization qubits are transferred into the state on time-bin degree of freedom. Additionally, the deterministic transmission of single photon quantum states can be achieved with high fidelity. The immunity of time-bin encoded qubits against collective noise paves the way to practical quantum error-correction and error-rejection in quantum information science. [ABSTRACT FROM AUTHOR]

Zero-intermediate frequency (IF) receiver features the advantages of compact structure and agile operating frequency, but faces the problems of local oscillator (LO) leakage, direct current (dc) offset, even-order distortion, and in-phase/quadrature (I/Q) imbalance. In this paper, a photonic microwave I/Q mixer for zero-IF receiver is proposed based on a single integrated polarization multiplexing Mach–Zehnder modulator (PDM-MZM). Thanks to its all-optical operation and LO power optimization, an I/Q phase imbalance below 0.9°, an isolation ratio below −30 dB, and a typical conversion gain of −2.3 dB are achieved over an ultra-wide operating frequency from 10 to 40 GHz. Combined with the balanced detection techniques, the dc offset and even-order distortions are well suppressed, and the typical third-order spurious free dynamic range is 107.9 dB $\cdot $ Hz ^{2/3} . Using the proposed photonic I/Q mixer, the vector signals with various modulation formats, carrier frequencies, and data rates (200–700 Mb/s) are directly demodulated to I/Q basebands, and the error vector magnitude and the bit rate error are measured with the power range from −25 to 15 dBm. Subharmonic vector I/Q demodulation is also experimentally demonstrated. The proposed all-optical, ultra-wideband and high-efficient microwave I/Q mixer is suitable for a zero-IF receiver and may find potential applications in electronic systems such as wideband wireless communications, frequency-hopping radar, or multiband satellite transponder. [ABSTRACT FROM PUBLISHER]

This paper presents a complete, compact, and low power consumption instrument designed for time-domain near-infrared spectroscopy. It employs two custom-designed pulsed diode lasers (operating at 830 and 670 nm, with average optical power higher than 2 mW at 40 MHz repetition frequency), a single-photon detection module (based on a 1 mm2 active area silicon photomultiplier), and a custom time-to-digital converter with 10 ps time resolution. The system experimental characterization shows an instrument response function narrower than 300 ps (full-width at half maximum), with measurement stability better than ±1% over several hours of operation. The instrument, which is housed into a compact aluminum case (size 200 × 160 × 50 mm3), is specifically tailored for portability and ease of operation, hence fostering the diffusion of time-domain diffuse optics techniques. Thanks to a total power consumption lower than 10 W, this system is suitable for battery operation, thus enabling on-field measurements. [ABSTRACT FROM PUBLISHER]

The performance of mid-infrared Er3+-doped fiber lasers has dramatically improved in the last few years. In this paper, we present a numerical model that provides valuable insight into the dynamics of a dual-wavelength pumped fiber laser that can operate on the 3.5- and 2.8- \mu \textm bands. This model is a much needed tool for optimizing and understanding the performance of these laser systems. Comparisons between simulation and experimental results for three different systems are presented. [ABSTRACT FROM PUBLISHER]

In this paper, two novel multidimensional striping noise compensation (SNC) algorithms for push-broom hyperspectral cameras (PBHCs) have been developed. The SNC algorithms employ a novel pixelwise, affine image-degradation model, which assumes that the striping noise (SN) parameters are spatially uncorrelated, spectrally independent, and decoupled from the camera’s spectral response. Algorithms simultaneously exploit the spatial and temporal information contained in an image as well as the spectral information contained at adjacent spectral images. The multidimensional SNC algorithms were successfully tested on real hyperspectral data from both a commercial PBHC operating in the spectral range of 400–1000 nm, at a resolution of 1.04 nm, and the ESA earth-observing CHRIS/PROBA sensor. [ABSTRACT FROM PUBLISHER]

We recently demonstrated orders of magnitude enhancement of two-photon absorption (2PA) in direct gap semiconductors due to intermediate state resonance enhancement for photons of very different energies. It can be expected that further enhancement of nondegenerate 2PA will be observed in quantum wells (QWs), since the intraband matrix elements do not vanish near the band center, as they do in the bulk, and the density of states in QWs is larger near the band edge. Here, we present a perturbation-theory-based theoretical description of nondegenerate 2PA in semiconductor QWs, where both the frequency and the polarization of two incident waves can vary independently. Analytical expressions for all possible permutations of frequencies and polarizations have been obtained, and the results are compared with the degenerate 2PA in QWs along with the degenerate 2PA and the nondegenerate 2PA in bulk semiconductors. We show that using QWs in place of bulk semiconductors with both the beams in the transverse magnetic-polarized mode leads to an additional order of magnitude increase in the nondegenerate 2PA. Explicit calculations for GaAs QWs are presented. [ABSTRACT FROM AUTHOR]

Recent technical and commercial milestones in Silicon Photonics technology including its introduction into commercial foundries, and successful integration of most optical components, as well as the choice of single mode fiber in some mega data centers have prompted the speculation that Si photonics is the new low cost solution for optical interconnects and that it may replace multi-mode vertical cavity surface emitting lasers (MM VCSEL). We show that the dominant technology has to offer the lowest cost for the single channel transceiver application, which represents 90% of the data center market and which historically dominates sales. We show that Si photonics is currently significantly more expensive than MM VCSEL for single channel, but that it can make a successful entry into the four channel single mode market with significant growth, capturing 20% of the data center market. We discuss the challenges with Si/InP integration; i.e., hybrid lasers for breaking the cost barrier and to enter the market. We show that both MM VCSEL and Si photonics technologies can operate at 50 Gb/s. We discuss the transmission reach limitations of Si photonics and MM VCSEL and show an example of reach extension for 100 Gb/s using MM VCSEL to 300 m of MM fiber. In addition we show that MM VCSEL has fundamentally lower power consumption than Si photonics and is a good candidate for super-computing applications. [ABSTRACT FROM PUBLISHER]

We present time-resolved laser-induced breakdown spectroscopy (LIBS) spectra of atomic (In I) and ionic (In II) indium lines recorded in time ranges from 500 ns to \(20~\mu \) s. Optical spectra have been acquired using a streak camera. Since it is assumed that the available supply of indium will slowly but inevitably diminish, the recycling of indium and finding the new natural sources are more and more important as the price of indium rises. The study of indium lines showed in this paper could be useful for making the LIBS detecting devices less expensive and more portable. [ABSTRACT FROM PUBLISHER]