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[Display omitted] Optical metasurfaces, i.e., subwavelength planar nanostructures, have attracted increasing attention due to their unprecedented capabilities of molding classical light and revolutionized conventional optics by replacing bulky optical components with ultrathin, lightweight, and ultracompact meta -optics. In addition to controlling classical light, meta -optics demonstrate the potential to efficiently manipulate nonclassical light and start to enter the realm of quantum photonics. Here, we briefly overview recent advances in quantum meta -optics for generation and manipulation of nonclassical light, highlighting innovative approaches, and discuss future opportunities in this burgeoning area, ranging from fundamental research to practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Interest in 3D (3- dimensional) printed optics and photonics by both industry and academic researchers is burgeoning, due to the unique features availed by 3D printing not achievable by traditional manufacturing techniques. 3D printing offers tremendous opportunities for developing new integrated systems in optics and photonics. Although a variety of manufacturing approaches have been developed, no single method can satisfy the requirement of small features, low roughness, and high speed simultaneously, thus opening up vast opportunities for innovations in 3D printed photonics. Besides the availability of state-of-the-art 3D printing technology, printable materials for the fabrication of 3D printed optics and photonics devices are also crucial. In this comprehensive review, we highlight the latest developments in 3D printing techniques, as well as developments in innovative practical technologies used for optics and photonics. In addition, we cover the latest progress in the materials used for 3D printed optics and photonics and future prospects in applications of 3D printed optics and photonics. The purpose of this review is to discuss technological and material advances, and potential future opportunities in the field of 3D printed optics and photonics. [ABSTRACT FROM AUTHOR]

Here we present a detailed analysis of a new concept for beam propulsion that extends the propagation range through space by circumventing fundamental limitations on the beam divergence. Using a combination of spatially overlapped continuous laser and neutral particle beams, opto-mechanical forces and light refraction are simultaneously exploited to produce self-guided modes. The aim of the present work is to elucidate the relevant physical phenomena, their relation to the conditions for self-guiding, and practical considerations for the design parameters of such a propulsion system. Methods for computing the lowest order axisymmetric self-guided modes are presented along with the resulting spatial mode structure. Key non-dimensional parameters are derived, including the use of linear stability analysis to determine features of the dynamic interaction. Based on these findings, a beam parameter optimization framework is proposed and applied to a 100-year interstellar flyby mission to Proxima b. With 200 GW of combined laser and particle beam power, we find that a 0.3 kg spacecraft could be accelerated to 0. 044 c over a distance of 4. 37 × 1 0 6 km (0.029 AU) using a small 1 m 2 beam cross-section. Compared to an equivalent particle beam with no self-guiding, this represents an over 50 × increase in payload. Similar payload mass would be possible by laser propulsion with an approximately 1 0 4 m 2 area laser array. These results suggest that self-guided beam propulsion possesses unique attributes that could enable the acceleration of larger spacecraft to relativistic velocities and enhance scientific capabilities for future interstellar and interstellar-precursor missions. [ABSTRACT FROM AUTHOR]

The real-time characterization of the polarization state of a light beam is of importance for a variety of applications in Optics and Photonics. We have designed a device that includes a Vector Diffractive Optical Element (VDOE) to determine the polarization state of an incident light beam. The device is able to simultaneously evaluate the four Stokes parameters of the light under analysis. The VDOE is sectorized into several Fresnel zone plates, enabling a compact arrangement and facilitating optoelectronical integration. We have also developed a procedure to remove diffractive effects and systematic errors. From the simulated results, our device is able to identify any polarization incident state with an averaged uncertainty of 0.006%. Finally, we have experimentally verified the VDOE with non-ideal polarization elements to further validate and test our proposed design. The averaged uncertainty of our experimental realization is 3.33%. [Display omitted] • A VDOE is designed and fabricated by adding polarization components within the sectorized aperture of a DOE. • The VDOE works as a full-Stokes analyzer, allowing simultaneous and fast measurements. • The proposed device is compact and potentially cheap. • A dedicated methodology to reduce uncertainties is described and successfully applied. • The associated uncertainties are 0.006% in simulation and 3.33% in experiments. [ABSTRACT FROM AUTHOR]

Abstract A novel photonic approach to generate frequency and bandwidth multiplying dual-chirp microwave for application in dual-band radar system is proposed using an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator. The proposed approach is based on optical frequency multiplying and polarization selection. In the approach, the baseband signal and RF signal are injected into the DP-QPSK modulator to generate optical broad spectra and sidebands respectively. By adjusting the bias points of the DP-QPSK modulator, after polarization selection and optical to electrical conversion, frequency-quadrupling bandwidth-octupling and frequency-double bandwidth-quadrupling or frequency-tripling bandwidth-sextupling and frequency-fundamental bandwidth-doubling dual-chirp signals can be generated in the single structure respectively. The proposed approach is verified by simulations. Dual-chirp microwaves with central frequency–bandwidth of 32 GHz-8 GHz, 16 GHz-4 GHz or 24 GHz-6 GHz, 8 GHz-2 GHz are generated in the two ports respectively. Their autocorrelation results manifest good pulse compression capabilities. The central frequency, bandwidth, chirp rate and time duration can be tuned independently. The generated dual-chirp signals show good performance on the range-Doppler coupling and can significantly improve the range-Doppler resolution in dual-band radar system. [ABSTRACT FROM AUTHOR]

We propose a general method for eliminating the reflection of waves in 2 dimensional photonic crystal waveguides (2D-PCWs), a kind of 2D material, by introducing extra scatterers inside the 2D-PCWs. The intrinsic reflection in 2D-PCWs is compensated by the backward-scattered waves from these scatterers, so that the overall reflection is greatly reduced and the insertion loss is improved accordingly. We first present the basic theory for the compensation method. Then, as a demonstration, we give four examples of extremely-low-reflection and high-transmission 90°bent 2D-PCWs created according to the method proposed. In the four examples, it is demonstrated by plane-wave expansion method and finite-difference time-domain method that the 90°bent 2D-PCWs can have high transmission ratio greater than 90% in a wide range of operating frequency, and the highest transmission ratio can be greater than 99.95% with a return loss higher than 43 dB, better than that in other typical 90°bent 2D-PCWs. With our method, the bent 2D-PCWs can be optimized to obtain high transmission ratio at different operating wavelengths. As a further application of this method, a waveguide-based optical bridge for light crossing is presented, showing an optimum return loss of 46.85 dB, transmission ratio of 99.95%, and isolation rates greater than 41.77 dB. The method proposed provides also a useful way for improving conventional waveguides made of cables, fibers, or metal walls in the optical, infrared, terahertz, and microwave bands. [ABSTRACT FROM AUTHOR]

A novel photonic digital-to-analog conversion (PDAC) scheme, which is based on optical intensity weighting and multiplexing/summing of different wavelengths, is proposed. The employment of wavelength multiplexing in the system, which conducts the function of modulated light intensity summation, greatly simplifies the system complexity and improves the conversion speed/accuracy limited by large-area photo-detectors and associated electronics. A 4-bit PDAC with a conversion speed of 10 GS/s demonstrates the feasibility of the proposed scheme. In addition, the performance degradation induced by the limited extinction ratios of the applied electro-optic modulators, the synchronization errors among different wavelength channels, and the bit resolutions of the built system is also discussed. [ABSTRACT FROM AUTHOR]

We describe a subluminal laser which is extremely stable against perturbations. It makes use of a composite gain spectrum consisting of a broad background along with a narrow peak. The stability of the laser, defined as the change in frequency as a function of a change in the cavity length, is enhanced by a factor given by the group index, which can be as high as 10 5 for experimentally realizable parameters. We also show that the fundamental linewidth of such a laser is expected to be smaller by the same factor. We first present an analysis where the gain profile is modeled as a superposition of two Lorentzian functions. We then present a numerical study based on a physical scheme for realizing the composite gain profile. In this scheme, the broad gain is produced by a high pressure buffer-gas loaded cell of rubidium vapor. The narrow gain is produced by using a Raman pump in a second rubidium vapor cell, where optical pumping is used to produce a Raman population inversion. We show close agreement between the idealized model and the explicit model. A subluminal laser of this type may prove to be useful for many applications. [ABSTRACT FROM AUTHOR]

An optical coherence tomography (OCT)-monitored laser ablation system is presented in this study. The laser ablation subsystem is constructed using the third harmonic output of a Nd:YAG laser source operating at a 355-nm optical wavelength with a single pulse energy greater than 160 mJ and a 1–10 Hz tunable repetition rate. The imaging subsystem is a typical M-mode swept-source OCT system. Moreover, a type of all-fiber multifunctional integrated catheter is demonstrated. The ablation catheter consists of a fiber bundle including 41 multi-mode fibers with an outer diameter of 0.9 mm. A forward-viewing OCT imaging probe is inserted into the ablation catheter for M-mode imaging. The performance of the system is demonstrated by OCT surveillance of the laser ablation process using expanded polystyrene foam as the sample. The OCT system can be used to record the ablation process and simultaneously count the laser ablation duration. This study proposes an effective potential technique to surveil material laser ablation processes, especially in situations where bulky optics are prohibited and all-fiber devices are required. [ABSTRACT FROM AUTHOR]

• Minimization of plasmonic losses in random laser through optimal spectral overlap between gain and scattering loss. • Tuning of the aspect ratio of nanorods to maximise scattering and field enhancement. • Low threshold random lasing with optimized plasmonic nanorods. • Characterization of spatial coherence of the plasmonic random laser. • Reduction of speckle contrast to human perception level using single pulse illumination for better quality imaging. Plasmonic random lasers continue to generate significant interest in the fields of optics and photonics due to their improved performance. This owes to the greater scattering strength and enhanced local field offered by the plasmonic scatterers. However, absorption losses and fluorescence quenching are the major setbacks to plasmonic random lasers. Design of plasmonic random lasers with low threshold and enhanced emission intensity continues to be a challenging area of research. This paper demonstrates that the use of one-dimensional anisotropic plasmonic structures can help to overcome these limitations to a great extent by manipulating the spectral overlap between the scatterers and gain medium. A low threshold random lasing system has been experimentally realized in this context, using Ag nanorods with aspect ratio tuned to give optimal scattering and field enhancement. The optimal aspect ratios were deduced using FDTD simulations and incoherent random lasing was experimentally demonstrated at a low threshold of 116 µJ/cm2 or 0.023 MW/cm2. We also demonstrate through spatial coherence measurements that the bright emission from the plasmonic random laser enables speckle contrast reduction upto 0.034 with single pulse illumination. [ABSTRACT FROM AUTHOR]

Thin films have many applications in the field of optics and photonics. One of these applications is the fabrication of high-reflection mirrors for high-power lasers. High-power lasers also require mirrors with high laser induced damage threshold (LIDT). In this research, firstly, considering the principles of simulation, we have tried to design two types of mirrors, all-dielectric and metal-dielectric. Therefore, they are suitable in terms of both the reflectance spectrum and LIDT at 10.6 μm. To simulate and fabricate these two types of mirrors, ZnSe and Ge have been used as substrates and for thin film layers, Ge and ZnS have been used. In metal-dielectric mirrors, gold layers have also been used on the substrate as the metal layers. After design and simulation, the process of mirrors' fabrication was done by electron beam evaporation technique and the reflectance spectrum of the samples was taken, which shows the reflectance of all-dielectric mirrors is more than 99% and that of Metal-dielectric mirrors is more than 99.9%. Finally, measuring the LIDT of these two types of mirrors was performed based on ISO21254-1 2011 standard which shows that the metal-dielectric mirror with ZnSe substrate is the most suitable mirror for continuous lasers at 10.6 μm. • Two types of mirrors were designed which are suitable in terms of reflectance and LIDT at 10600 nm. • The reasons for metal-dielectric Mirrors' design are reducing the number of layers and the cost. • Reflectance of fabricated all-dielectric mirrors is more than 99% and that of Metal-dielectric mirrors is more than 99.9%. • LIDT measuring was performed based on ISO21254-1 2011 standard. • Standard measurements show metal-dielectric mirror with ZnSe substrate is the most suitable mirror at 10600 nm. [ABSTRACT FROM AUTHOR]

This review focuses on the role that micro and nanotechnologies are having in the development of a new generation of optical neural interfaces for deep brain regions. The advent of optical methods to control and monitor neural activity has indeed raised neuroscientists' demand for small, soft and multifunctional devices to interface with sub-cortical structures. These are indeed widely inaccessible with microscopy-based approaches, and the scientific community has proposed complementary methods based on integrated photonics, implantable micro LEDs and engineered optical fibers. After discussing advantages and drawbacks of these methods, the manuscript closes with an overview on the emerging field of optical neural interfaces based on colloidal nanoparticles. Unlabelled Image • Micro and nanotechnologies are a key for next generation of optical neural interfaces. • Integrated photonics is one of the main roads to realize fully integrated devices. • Implantable μLEDs allow for wireless optical stimulation of neural activity. • Engineered optical fibers reach sub-cortical structures with reduced invasiveness. • Nanoparticles bring quantum confinement and light-matter interactions in the brain. [ABSTRACT FROM AUTHOR]