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.
Highly sensitive and broadband ultrasound detection is important for photoacoustic imaging, biomedical ultrasound, and ultrasonic nondestructive testing.
Highly sensitive and broadband ultrasound detection is important for photoacoustic imaging, biomedical ultrasound, and ultrasonic nondestructive testing. The elasto-optical refractive index modulation induced by ultrasound arouses a transient phase shift of a probe beam. Highly sensitive phase detection with a high Q factor resonator is desirable to visualize the ultraweak transient ultrasonic field. However, current phase-sensitive ultrasonic detectors suffer from limited bandwidth, mutual interference between intensity and phase, and significant phase noise, which become key to limiting further improvement of detection performance. We report a phase-sensitive detector with a bandwidth of up to 100 MHz based on dual-comb multiheterodyne interferometry (DCMHI). By sensing the phase shift induced by the ultrasound without any resonators in the medium, the DCMHI boosted the phase sensitivity by coherent accumulation without any magnitude averaging and extra radio frequency amplification. DCMHI offers high sensitivity and broad bandwidth as the noise-equivalent pressure reaches 31 mPa / √Hz under 70 MHz acoustic responses. With a large repetition rate difference of up to 200 MHz of dual comb, DCMHI can achieve broadband acoustic responses up to 100 MHz and a maximum possible imaging acquisition rate of 200 MHz. It is expected that DCMHI can offer a new perspective on the new generation of optical ultrasound detectors.show less
In light-sheet fluorescence microscopy, the axial resolution and field of view are mutually constrained. Axially swept light-sheet microscopy (ASLM) can d
In light-sheet fluorescence microscopy, the axial resolution and field of view are mutually constrained. Axially swept light-sheet microscopy (ASLM) can decouple the trade-off, but the confocal detection scheme using a rolling shutter also rejects fluorescence signals from the specimen in the field of interest, which sacrifices the photon efficiency. Here, we report a laterally swept light-sheet microscopy (LSLM) scheme in which the focused beam is first scanned along the axial direction and subsequently laterally swept with the rolling shutter. We show that LSLM can obtain a higher photon efficiency when similar axial resolution and field of view can be achieved. Moreover, based on the principle of image scanning microscopy, applying the pixel reassignment to the LSLM images, hereby named iLSLM, improves the optical sectioning. Both simulation and experimental results demonstrate the higher photon efficiency with similar axial resolution and optical sectioning. Our proposed scheme is suitable for volumetric imaging of specimens that are susceptible to photobleaching or phototoxicity.show less
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
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
Recently, the metasurfaces for independently controlling the wavefront and amplitude of two orthogonal circularly polarized electromagnetic waves have been demonstrated to open a new wa
Recently, the metasurfaces for independently controlling the wavefront and amplitude of two orthogonal circularly polarized electromagnetic waves have been demonstrated to open a new way towards spin-multiplexing compact meta-devices. However, these metasurfaces are mostly restricted to a single operation frequency band. The main challenging to achieve multiple frequency manipulations stems from the complicated and time-consuming design caused by multi-frequency crosstalk. To solve this problem, here we propose a deep-learning-assisted inverse design method for designing dual-spin/frequency metasurface with flexible multiplexing of off-axis vortices. By analyzing the cross-talk between different spin/frequency channels based on deep learning method, we established the internal mapping relationship between the physical parameters of meta-atom and its phase responses in multi-channels, realizing the rapid inverse design of the spin/frequency multiplexing electromagnetic device. As a proof of concept, we demonstrated in microwave region a dual-frequency arbitrary spin-to-orbit angular momentum converter, a dual-frequency off-axis vector vortex multiplexer, and large-capacity (16-channel) vortex beams generator. The proposed method may provide a compact and efficient platform for the multiplexing of vortices, which may further stimulate their applications in wireless communications and quantum information science.show less
Multi-mode optical interferometers represent the most viable platforms for successful implementation of several quantum information schemes that take advantage of optical processing. Ex
Multi-mode optical interferometers represent the most viable platforms for successful implementation of several quantum information schemes that take advantage of optical processing. Examples range from quantum communication, sensing and computation, including optical neural networks, optical reservoir computing or simulation of complex physical systems. The realization of such routines requires high levels of control and tunability of the parameters that define the operations carried out by the device. This requirement becomes particularly crucial in light of recent technological improvements in integrated photonic technologies, which enable the implementation of progressively larger circuits embedding a considerable amount of tunable parameters. In this work, we formulate efficient procedures for the characterization of optical circuits in the presence of imperfections that occur in physical experiments, such as unbalanced losses and phase instabilities. The algorithm aims at reconstructing the transfer matrix that represent the optical interferometer without making any strong assumption on its internal structure and encoding. We show the viability of this approach in an experimentally relevant scenario, defined by a tunable integrated photonic circuit, and we demonstrate the effectiveness and robustness of our method. Our findings can find application in a wide range of optical setups, based both on bulk and integrated configurations.show less
Structured light fields embody strong spatial variations of polarisation, phase and amplitude. Understanding, characterization and exploitation of such fields can be achieved through th
Structured light fields embody strong spatial variations of polarisation, phase and amplitude. Understanding, characterization and exploitation of such fields can be achieved through their topological properties. Three-dimensional (3D) topological solitons, such as hopfions, are 3D localized continuous field configurations with nontrivial particle-like structures, that exhibit a host of important topologically protected properties. Here, we propose and demonstrate photonic counterparts of hopfions with exact characteristics of Hopf fibration, Hopf index, and Hopf mapping from real-space vector beams to homotopic hyperspheres representing polarisation states. We experimentally generate photonic hopfions with on-demand high-order Hopf indices and independently controlled topological textures, including N'eel-, Bloch-, and anti-skyrmionic types. We also demonstrate a robust free-space transport of photonic hopfions, thus, showing potential of hopfions for developing optical topological informatics and communications.show less
We report continuous-wave deep red lasers at 696.6 nm and 698.6 nm in Pr3+:YLF crystal pumped by an InGaN laser diode. A Lyot filter was inserted into the cavity as a birefringent filte
We report continuous-wave deep red lasers at 696.6 nm and 698.6 nm in Pr3+:YLF crystal pumped by an InGaN laser diode. A Lyot filter was inserted into the cavity as a birefringent filter to select wavelength, the laser at 696.6 nm and 698.6 nm were obtained with a maximum output power of 1.36 W and 3.11 W, separately. To the best of our knowledge, the output powers of these two lasers are the highest to date, and this is the first scaling of the output power of the Pr3+:YLF laser to the watt level at around 696 nm. In addition, the corresponding theoretical analysis and simulation were carried out to explain the experimental phenomena. show less