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This mutual interaction gives rise to a family of nonlinear-nonlocal effects which can be studied in the proposed chip-scale photonic circuits. The authors suggest and numerically demonstrate that optically driven liquid deformation can serve as an optical memory capable of storing information and performing neuromorphic computing in a compact actuation region. A key element in the proposed photonic platform is a nanoscale gold patch located on the optical waveguide operating as an optical heater and consequently generating thermocapillary-driven thickness changes in a liquid film covering the waveguide. The image on the cover for Advanced Photonics Volume 4 Issue 4 provides a visual rendering of the process.

Researchers from the National University of Singapore (NUS), Huazhong University of Science and Technology (HUST), Agency for Science, Technology and Research (A*STAR), and Nanyang Technological University (NTU) recently summarized advances in LN photonics in detail in their paper "Advances in lithium niobate photonics: development status and perspectives", Advanced Photonics 4 (3), 034003. (2022). It also includes the integrated LN photonics devices which have appeared in recent years, as well as selected bulk LN based devices and related processing technologies. In this way, the research community can reach a better, comprehensive understanding of the technology evolution of LN photonics.

Recently, in a paper published in High Power Laser Science and Engineering , Vol. 10, Issue, 4 (A. X. Li, C. Y. Qin, et al., Acceleration of 60 MeV proton beams in the commissioning experiment of SULF-10 PW laser, High Power Laser Science and Engineering, 2022, 10(4): 04000e26), a research group from Shanghai Institute of Optics and Fine Mechanics (SIOM) reports the experimental results in the commissioning phase of the 10 PW laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF), achieving high-energy proton beams with energies up to 62.5 MeV.

We are studying the internal conversion between the two excited states, the highest and directly reachable from the initial ground state being considered as a donor and the lowest as an acceptor.

This paper reviews the relevant research results and state-of-the-art technologies on the silicon photonic chip for scalable quantum applications. Despite the shortcomings, the properties of some components have already met the requirements for further expansion. Furthermore, we point out the challenges ahead and future research directions for on-chip scalable quantum information applications.

Community-News
Call for access to OCTOPUS and ULTRA is now open. Applications for access to the Octopus and Ultra facilities of the Central Laser Facility (CLF) in the Research Complex at Harwell are open from Friday 25th November 2022.
High Power Laser Science and Engineering
• Nov. 29, 2022
• Vol. , Issue (2022)
Editors' Picks
The MIR region (2.5-25 μm) is associated with nature-given properties covering vibrations or rotational transitions of complex molecules. As a result, ultra-sensitive MIR spectroscopy has emerged as an important technique for intelligent biochemical sensing, new materials investigation, environmental gas monitoring, and high-precision medical tomography.
Photonics Research
• Nov. 24, 2022
• Vol. 10, Issue 11 (2022)
Community-News
A record high-laser-energy NIF target shot on Sept. 19 produced about 1.2 million joules of fusion energy yield, putting NIF back on track toward ignition.
High Power Laser Science and Engineering
• Nov. 23, 2022
• Vol. , Issue (2022)
On the Cover
Structured light three-dimensional (3D) reconstruction has been widely used in medicine, aerospace and other industrial fields. As one of the 3D reconstruction methods of structured light, phase-shifting profilometry (PSP) has attracted much attention due to its high accuracy and robustness. PSP is used to obtain the 3D shape of objects by collecting and solving the fringe patterns projected onto the object surface with phase information. The phase information of PSP has periodic phase ambiguity of (0-2π). The traditional method requires additional fringe patterns to determine the fringe period, which undoubtedly increases the time cost and limits the area of usage scenarios. With the increased of application scenarios such as dynamic object reconstruction and real-time object scanning in industry, traditional PSP cannot meet the requirements.
Chinese Optics Letters
• Nov. 22, 2022
• Vol. 20, Issue 11 (2022)
Spotlight on Optics
Fast transient events, such as chemical reactions, plasma formation and laser induced damage involve processes that occur at different timescales. Consider for example a plasma assisted reaction event. On the one hand the actual discharge necessitates ultra-high imaging speeds in order to capture its evolution (on the order of THz), while on the other hand, the shockwave induced by the chemical reactions following the plasma pulse moves at a much slower rate.
Photonics Research
• Nov. 21, 2022
• Vol. 10, Issue 7 (2022)
Direct measurement of topological invariants in photonic superlattices

Since the discovery of topological insulators, topological phases have generated considerable attention across the physics community. The superlattices in

Since the discovery of topological insulators, topological phases have generated considerable attention across the physics community. The superlattices in particular offer a rich system with several degrees of freedom to explore a variety of topological characteristics and control the localization of states. Albeit their importance, characterizing topological invariants in superlattices consisting of a multi-band structure is challenging beyond the basic case of two-bands as in the Su–Schreifer–Heeger model. Here, we experimentally demonstrate the direct measurement of the topological character of chiral superlattices with broken inversion symmetry. Using a CMOS-compatible nanophotonic chip, we probe the state evolving in the system along the propagation direction using novel nanoscattering structures. We employ a two-waveguide bulk excitation scheme to the superlattice, enabling the identification of topological zero-energy modes through measuring the beam displacement. Our measurements reveal quantized beam displacement corresponding to 0.088 and -0.245, in the cases of trivial and nontrivial photonic superlattices, respectively, showing good agreement with the theoretical values of 0 and -0.25. Our results provide direct identification of the quantized topological numbers in superlattices using a single-shot approach, paving the way for direct measurements of topological invariants in complex photonic structures using tailored excitations with Wannier functions.show less

• Dec.06，2022
• Editors' Pick
• Photonics Research,Vol. 10, Issue 12
• 2901 (2022)
High color saturation and angle-insensitive ultrathin color filter based on effective medium theory

An ultrathin angle-insensitive color filter enabling high color saturation and a wide color gamut is proposed by relying on a magnesium hydride-hydrogenat

An ultrathin angle-insensitive color filter enabling high color saturation and a wide color gamut is proposed by relying on a magnesium hydride-hydrogenated amorphous silicon (MgH2-a-Si:H) lossy dielectric layer. Based on effective medium theory, the MgH2-a-Si:H layer with an ultrathin thickness can be equivalent to a quasi-homogeneous dielectric layer with an effective complex refractive index, which can be tuned by altering the thickness of MgH2 to obtain the targeted value of the imaginary part, corresponding to the realization of high color saturation. It is verified that the proposed color filter offers highly enhanced color saturation in conjunction with a wide color gamut by introducing a few-nanometer thick MgH2 layer. As the MgH2-a-Si:H layer retains the advantages of high refractive index and tiny thickness, the proposed color filter exhibits large angular tolerance up to $±60°$. In addition, MgH2 with an unstable property can interconvert with Mg under a dehydrogenation/hydrogenation reaction, which empowers the proposed color filter with dynamically tunable output color. The proposed scheme shows great promise in color printing and ultracompact display devices with high color saturation, wide gamut, large angular tolerance, and dynamic tunability.show less

• Dec.06，2022
• Chinese Optics Letters,Vol. 21, Issue 3
• 033602 (2023)
Advances in multipass cell for absorption spectroscopy-based trace gas sensing technology [Invited]

In the field of absorption spectroscopy, the multipass cell (MPC) is one of the key elements. It has the advantages of simple structure, easy adjustment,

In the field of absorption spectroscopy, the multipass cell (MPC) is one of the key elements. It has the advantages of simple structure, easy adjustment, and high spectral coverage, which is an effective way to improve the detection sensitivity of gas sensing systems such as tunable diode laser absorption spectroscopy. This invited paper summarizes the design theory and the research results of some mainstream types of MPCs based on two mirrors and more than two mirrors in recent years, and briefly introduces the application of some processed products. The design theory of modified ABCD matrix and vector reflection principle are explained in detail. Finally, trends in its development are predicted.show less

• Dec.06，2022
• Chinese Optics Letters,Vol. 21, Issue 3
• 033001 (2023)
High numerical aperture RGB achromatic metalens in the visible

We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths (λ=450, 532, and 700 nm

We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths ($λ=450$, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is designed by simple integration of metalens components with the spatial interleaving method. The simulated spatial interleaving metalens shows RGB achromatic operation with focusing efficiencies of 25.2%, 58.7%, and 66.4% at the wavelengths of 450, 532, and 700 nm, respectively. A 450 μm diameter metalens operating at three designated wavelengths is fabricated with low-loss hydrogenated amorphous silicon. The fabricated metalens has the measured focusing efficiencies of 5.9%, 11.3%, and 13.6% at $λ=450$, 532, and 700 nm, respectively. The Strehl ratios of 0.89, 0.88, and 0.82 are obtained at given wavelengths, which show a capability of diffraction-limited operation.show less

• Dec.06，2022
• Photonics Research,Vol. 10, Issue 12
• B30 (2022)

Parity‐time (PT) symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator (OEO) loop. However, most OEO implementati

Parity‐time (PT) symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator (OEO) loop. However, most OEO implementations depend on discrete devices, which impedes the proliferation due to size, weight, power consumption and cost. Here, we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO. A tunable microwave photonic filter, a PT‐symmetric mode‐selective architecture, and two photodetectors are integrated on a silicon‐on‐insulator chip. By exploiting an on‐chip Mach‐Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops, single‐mode oscillation can be obtained. In the experiment, the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz. To emulate the integrated case, the OEO loop length is minimized and no extra long fiber is used in the experiment. When the oscillation frequency is 13.67 GHz, the single‐sideband phase noise at 10 kHz offset frequency is −80.96 dBc/Hz and the side mode suppression ratio is 46 dB. The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.show less

• Dec.06，2022

Electrically connected optical metasurfaces with high efficiencies are crucial for developing spatiotemporal meta-devices with ultrahigh spatial and ultrafast temporal resolutions. Whil

Electrically connected optical metasurfaces with high efficiencies are crucial for developing spatiotemporal meta-devices with ultrahigh spatial and ultrafast temporal resolutions. While efficient metal-insulator-metal (MIM) metasurfaces containing discretized meta-atoms require additional electrodes, Babinet-inspired slot-antenna-based plasmonic metasurfaces are suffering from low efficiencies and limited phase coverage for co-polarized optical fields. Capitalizing on the concepts of conventional MIM and slot-antenna metasurfaces, we design and experimentally demonstrate a new type of optical reflective metasurfaces consisting of mirror-coupled slot antennas. By tuning the dimensions of rectangular-shaped nano-apertures atop a dielectric-coated gold mirror, we achieve efficient phase modulation within a sufficiently large range of 320° and realize functional phase-gradient meta-devices for beam steering and beam splitting in the near-infrared range. The fabricated samples show (22 ± 2)% diffraction efficiency for beam steering and (17 ± 1)% for beam splitting at the wavelength of 790 nm. The considered mirror-coupled slot-antenna configuration, dispensing with auxiliary electrodes, offers an alternative and promising platform for electrically controlled reflective spatiotemporal metasurfaces. show less

• Dec.06，2022

The explosion in the amount of information that is being processed is prompting the need for new computing systems beyond existing electronic computers. Photonic computing is emerging a

The explosion in the amount of information that is being processed is prompting the need for new computing systems beyond existing electronic computers. Photonic computing is emerging as an attractive alternative due to performing calculations at the speed of light, the change for massive parallelism, and also extremely low energy consumption. Here, we review the physical implementation of basic optical calculations, such as differentiation and integration, using metamaterials, and introduce the realization of all optical artificial neural networks. We start with concise introductions of the mathematical principles behind such optical computation methods and present the advantages, current problems that need to be overcome, and the potential future directions in the field. We expect that this review will be useful for both novice and experienced researchers in the field of all-optical computing platforms using metamaterials.show less

• Dec.06，2022