Photonic Generation Research Articles

Photonic generation of frequency agile LFM signals for ISAC systems

Photonic generation of frequency agile LFM signals for ISAC systems

Photonic hook shaping achieved by the micro-nano fiber array based Janus cylindrical metalens

Abstract Near-field focusing of an electromagnetic wave on the assembly of hexagonally asymmetric arranged close-contact nanofibers into a cylindrical Janus metalens is considered for different fiber sizes and optical properties. We propose combining the meta-material concept with a photonic hook based on the finite-difference time-domain technique. Simulation results show that the cylindrical meta-photonic Janus structure produces the focal region of enhanced optical intensity, which exists in the spatial form of a localized structured light known as a photonic hook. A detailed study of all key parameters of a photonic hook depending on the Janus metalens topology and optical properties of the fiber filling is carried out. The structure conditions have been determined for the beam waist of a photonic hook that is less than the diffraction limit. This Janus cylindrical metalens may contribute to the versatile control of photonic hook generation in the applications of bio-photonics and optical microscopes.

High-dimensional spin-orbital single-photon sources.

Hybrid integration of solid-state quantum emitters (QEs) into nanophotonic structures opens enticing perspectives for exploiting multiple degrees of freedom of single-photon sources for on-chip quantum photonic applications. However, the state-of-the-art single-photon sources are mostly limited to two-level states or scalar vortex beams. Direct generation of high-dimensional structured single photons remains challenging, being still in its infancy. Here, we propose a general strategy to design highly entangled high-dimensional spin-orbital single-photon sources by taking full advantage of the spatial freedom to design QE-coupled composite (i.e., Moiré/multipart) metasurfaces. We demonstrate the generation of arbitrary vectorial spin-orbital photon emission in high-dimensional Hilbert spaces, mapping the generated states on hybrid-order Bloch spheres. We further realize single-photon sources of high-dimensional spin-orbital quantum emission and experimentally verify the entanglement of high-dimensional superposition states with high fidelity. We believe that the results obtained facilitate further progress in integrated solutions for the deployment of next-generation high-capacity quantum information technologies.

Two-cavity-mediated photon-pair emission by one atom

Photon-pair sources are widely used in quantum optics and quantum information experiments. Despite their broad deployment, there has not yet been an on-demand implementation with efficient into-fiber photon generation and high single-photon purity. Here we report on such a source based on a single atom with three energy levels in ladder configuration and coupled to two optical fiber cavities. We efficiently generate photon pairs with an in-fiber emission efficiency of ηpair=16(1)% and study their temporal correlation properties. We simulate theoretically a regime with strong atom–cavity coupling and find that photons are directly emitted from the ground state, i.e., without atomic population in any intermediate state. We propose a scenario to observe such a double-vacuum-stimulated effect experimentally.

InGaP χ(2) integrated photonics platform for broadband, ultra-efficient nonlinear conversion and entangled photon generation

Nonlinear optics plays an important role in many areas of science and technology. The advance of nonlinear optics is empowered by the discovery and utilization of materials with growing optical nonlinearity. Here we demonstrate an indium gallium phosphide (InGaP) integrated photonics platform for broadband, ultra-efficient second-order nonlinear optics. The InGaP nanophotonic waveguide enables second-harmonic generation with a normalized efficiency of 128, 000%/W/cm2 at 1.55 μm pump wavelength, nearly two orders of magnitude higher than the state of the art in the telecommunication C band. Further, we realize an ultra-bright, broadband time-energy entangled photon source with a pair generation rate of 97 GHz/mW and a bandwidth of 115 nm centered at the telecommunication C band. The InGaP entangled photon source shows high coincidence-to-accidental counts ratio CAR > 104 and two-photon interference visibility > 98%. The InGaP second-order nonlinear photonics platform will have wide-ranging implications for non-classical light generation, optical signal processing, and quantum networking.

Van der Waals engineering for quantum-entangled photon generation

Van der Waals engineering for quantum-entangled photon generation

Tetrahydrofuran Processable Organic Solar Cells with 19.45% Efficiency Realized by Introducing High Molecular Dipole Unit Into the Terpolymer.

Developing organic solar cells (OSCs) processable with halogen-free, non-aromatic solvents is crucial for practical applications, yet challenging due to the limited solubility of most photoactive materials. This study introduces high-performance terpolymers processable in tetrahydrofuran (THF) by incorporating dithienophthalimide (DPI) into the PM6 backbone. DPI extends the absorption band, lowers HOMO levels, and improves THF solubility and film crystallinity through its large dipole moment effect. Optimal PBD-10:L8-BO devices processed with THF achieved a competitive power conversion efficiency (PCE) of 18.79%, approaching chloroform-processed devices (19.04%). By introducing PBTz-F as a second donor, ternary OSCs reached an impressive 19.45% PCE when processed with THF. This improvement stems from enhanced photon generation, improved morphology, better charge transport, longer exciton lifetimes, efficient charge dissociation and collection, and suppressed recombination. These PCEs of 18.79% and 19.45% for binary and ternary blend OSCs, respectively, represent the highest reported efficiencies for OSCs processed with halogen-free, non-aromatic solvents. This work demonstrates significant progress in eco-friendly OSC fabrication, paving the way for more sustainable and commercially viable organic photovoltaic technologies.

Ultra-Wideband Photonic Frequency-Hopping Waveform Generator Enabled by Optical Injection Locking for Secure Terahertz Wireless Communications

Ultra-Wideband Photonic Frequency-Hopping Waveform Generator Enabled by Optical Injection Locking for Secure Terahertz Wireless Communications

Emulating quantum computing with optical matrix multiplication

Optical computing harnesses the speed of light to perform vector-matrix operations efficiently. It leverages interference, a cornerstone of quantum computing algorithms, to enable parallel computations. In this work, we interweave quantum computing with classical structured light by formulating the process of photonic matrix multiplication using quantum mechanical principles such as state superposition and subsequently demonstrate a well-known algorithm, namely, Deutsch–Jozsa’s algorithm. This is accomplished by elucidating the inherent tensor product structure within the Cartesian transverse degrees of freedom of light, which is the main resource for optical vector-matrix multiplication. To this end, we establish a discrete basis using localized Gaussian modes arranged in a lattice formation and demonstrate the operation of a Hadamard gate. Leveraging the reprogrammable and digital capabilities of spatial light modulators, coupled with Fourier transforms by lenses, our approach proves adaptable to various algorithms. Therefore, our work advances the use of structured light for quantum information processing.

Photonic Generation of Arbitrary Microwave Waveforms with Anti-Dispersion Transmission Capability

We propose and demonstrate a photonic-assisted approach for generating arbitrary microwave waveforms based on a dual-polarization dual-parallel Mach–Zehnder modulator, offering significant advantages in terms of tunability of repetition rates and anti-dispersion capability. In order to generate diverse microwave waveforms, two sinusoidal radio frequency signals with distinct frequency relationships are applied to the dual-polarization dual-parallel Mach–Zehnder modulator. By adjusting the power of the applied sinusoidal radio frequency signal, the power ratio between these orthogonal polarized optical sidebands can be changed, and thereby desired radio frequency waveforms can be obtained after photoelectric conversion. In our proof-of-concept experiment, we systematically varied the repetition rate of triangular, rectangular and sawtooth waveforms. Meanwhile, we calculated the Root Mean Square Error (RMSE) to assess the approximation error in each waveform. The RMSEs are 0.1089, 0.2182 and 0.1185 for the triangular, rectangular and sawtooth microwave waveforms with repetition rate of 8 GHz, respectively. Furthermore, after passing through 25 km single mode fiber, the optical power decreased by approximately 5.6 dB, which verifies the anti-dispersion transmission capability of our signal generator.

Photonic generation and transmission of dual-band double-TBWP chirped microwave waveforms with frequency multiplication and immunity to dispersion-induced power fading

A novel photonic approach for generating and transmitting dual-band double-time bandwidth product (TBWP) chirped microwave waveforms with frequency multiplication and immunity to dispersion-induced power fading is proposed. Utilizing an integrated dual-drive dual-parallel Mach-Zehnder modulator (DD-DPMZM), single-sideband modulation of the RF input and suppression of odd-order optical sidebands are achieved. By adjusting the RF input's centre frequency and the DD-DPMZM's bias voltages, dual-band waveforms with frequency multiplication are realized, enabling transmission through optical fibres without dispersion-induced power fading. Experimental validation demonstrates successful transmission over dispersion compensation modules equivalent to 60 km or 20 km of single-mode fibre. The proposed system features a simplified architecture, reconfigurability, and robust anti-dispersion capabilities, making it highly suitable for distributed multi-band radar networks over optical fibre links.

Photonic generation and programmable switching of variable-band chirped waveforms with immunity to power fading.

A photonic approach for generating and programmable switching variable-band chirped waveforms by using a dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. By coupling binary switching codes with the baseband chirped signal and applying them into the RF input port of DPMZM, the variable-band chirped waveforms can be generated and fast switched. The switching speed is consistent with the input code bit rate. Moreover, by properly adjusting the bias voltages, the generated signals can be anti-dispersion transmitted over different distances. Full experimental verification on the generation and programmable switching of the chirped waveforms centered at 2.1, 6.3, and 8.4 GHz or 1.5, 4.5, and 6 GHz over 10 or 20 km standard single-mode fibers with 4 or 100 Mbps switching rates are successfully carried out. The proposed approach features compact architecture, programmable switching capability and immunity to power fading, which are significant in distributed multifunction radar networks with optical fiber-based transmission.

Experimental measurements of gamma-photon production and estimation of electron/positron production on the PETAL laser facility

This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser (PETAL) laser. The experiments were performed during the commissioning of the laser. The laser had an energy of about 400 J, an intensity of 8 × 1018 W·cm−2, and a pulse duration of 660 fs (FWHM). It was shot at a 2 mm-thick solid tungsten target. The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target. This paper reports measurements of electrons, protons and photons. Hot electrons up to ≈35 MeV with a few-MeV temperature were recorded by a spectrometer, called SESAME (Spectre ÉlectronS Angulaire Moyenne Énergie). K- and L-shells were clearly detected by a photon spectrometer called SPECTIX (Spectromètre Petal à Cristal en TransmIssion pour le rayonnnement X). High-energy photons were diagnosed by CRACC-X (Cassette de RAdiographie Centre Chambre-rayonnement X), a bremsstrahlung cannon. Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape. Different shapes can exhibit similar reproductions of the experimental data. To eliminate dependence on the shape hypothesis and to facilitate analysis of the data, simulations of the interaction were performed. To model the mechanisms involved, a simulation chain including hydrodynamic, particle-in-cell, and Monte Carlo simulations was used. The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse, the acceleration of electrons inside the plasma, the generation of MeV-range photons from these electrons, and the response of the detector impacted by the energetic photon beam. All this work enabled reproduction of the experimental data. The high-energy photons produced have a large emission angle and an exponential distribution shape. In addition to the analysis of the photon spectra, positron production was also investigated. Indeed, if high-energy photons are generated inside the solid target, some positron/electron pairs may be produced by the Bethe–Heitler process. Therefore, the positron production achievable within the PETAL laser facility was quantified. To conclude the study, the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.

GraphiQ: Quantum circuit design for photonic graph states

GraphiQ is a versatile open-source framework for designing photonic graph state generation schemes, with a particular emphasis on photon-emitter hybrid circuits. Built in Python, GraphiQ consists of a suite of design tools, including multiple simulation backends and optimization methods. The library supports scheme optimization in the presence of circuit imperfections, as well as user-defined optimization goals. Our framework thus represents a valuable tool for the development of practical schemes adhering to experimentally-relevant constraints. As graph states are a key resource for measurement-based quantum computing, all-photonic quantum repeaters, and robust quantum metrology, among others, we envision GraphiQ's broad impact for advancing quantum technologies.

Evaluation of TOPAS MC tool performance in optical photon transport and radioluminescence-based dosimetry

Radiation therapy plays a pivotal role in modern cancer treatment, demanding precise and accurate dose delivery to tumor sites while minimizing harm to surrounding healthy tissues. Monte Carlo simulations have emerged as indispensable tools for achieving this precision, offering detailed insights into radiation transport and interaction at the subatomic level. As the use of scintillation and luminescence dosimetry becomes increasingly prevalent in radiation therapy, there arises a need for validated Monte Carlo tools tailored to optical photon transport applications. In this paper, an evaluation process of the TOPAS (TOol for PArticle Simulation) Monte Carlo tool for Cerenkov light generation, optical photon transport and radioluminescence based dosimetry is presented. Three distinct sources of validation data are utilized: one from a published set of experimental results and two others from simulations performed with the Geant4 code. The methodology employed for evaluation includes the selection of benchmark experiments, making use of opt3 and opt4 Geant4 physics models and simulation setup, with observed slight discrepancies within the calculation uncertainties. Additionally, the complexities and challenges associated with modeling optical photons generation through luminescence or Cerenkov radiation and their transport are discussed. The results of our evaluation suggests that TOPAS can be used to reliably predict Cerenkov generation, luminescence phenomenon and the behavior of optical photons in common dosimetry scenarios.

Continuous spectral and coupling-strength encoding with dual-gradient metasurfaces.

To control and enhance light-matter interactions at the nanoscale, two parameters are central: the spectral overlap between an optical cavity mode and the material's spectral features (for example, excitonic or molecular absorption lines), and the quality factor of the cavity. Controlling both parameters simultaneously would enable the investigation of systems with complex spectral features, such as multicomponent molecular mixtures or heterogeneous solid-state materials. So far, it has been possible only to sample a limited set of data points within this two-dimensional parameter space. Here we introduce a nanophotonic approach that can simultaneously and continuously encode the spectral and quality-factor parameter space within a compact spatial area. We use a dual-gradient metasurface design composed of a two-dimensional array of smoothly varying subwavelength nanoresonators, each supporting a unique mode based on symmetry-protected bound states in the continuum. This results in 27,500 distinct modes and a mode density approaching the theoretical upper limit for metasurfaces. By applying our platform to surface-enhanced molecular spectroscopy, we find that the optimal quality factor for maximum sensitivity depends on the amount of analyte, enabling effective molecular detection regardless of analyte concentration within a single dual-gradient metasurface. Our design provides a method to analyse the complete spectral and coupling-strength parameter space of complex material systems for applications such as photocatalysis, chemical sensing and entangled photon generation.

Integrated photonic cryptographic key generator using low-power MEMS-on-PIC technology

Integrated photonic cryptographic key generator using low-power MEMS-on-PIC technology

(Invited) Photoluminescence Properties of Single InAsP Quantum Dots Embedded in InP Nanowires

Non-classical light emitters that can generate single photons with a negligible multiphoton probability are one of the key components for quantum information technologies. Deterministically grown III-V semiconductor nanowires containing quantum dots are gaining interest as a viable platform for quantum key distribution applications. In this talk, we will report on our recent development of the fabrication of InAsP single quantum dots embedded within InP photonic waveguide nanowires. In particular, we outline the importance of the photonic waveguide design for optimum photon generation and coupling to external optics [1]. The measured count rate dependence on normalized wire diameter, D/λ (figure 1) of the nanowire sources is consistent with calculations of the spontaneous emission rate into the fundamental HE11 nanowire waveguide mode (ΓHE11). Manipulating dot growth conditions and engineering the band structure around the dot (dot-in-a-rod configuration) are applied [2] to enhance the photoluminescence emission rate at 1310 nm and 1550 nm. Single photon emission with very low multiple photon probability is demonstrated at O- and C-band [3,4]. Temperature dependent, second-order correlation measurements on the 1310 nm source show that these nanowire sources can generate single photons up to temperatures of 220 K [3].[1] S. Haffouz, et al., Nano Letters, 18, 3047 (2018).[2] S. Haffouz, et al., Applied Physics Letters, 117, 113101 (2020).[3] P. Laferriére, et al., Nano Letters, 23, 962 (2023).[4] A.N. Wakileh, et al., arXiv:2309.13381 (2023). Figure 1

Continuous and deterministic all-photonic cluster state of indistinguishable photons

Cluster states are key resources for measurement-based quantum information processing. Photonic cluster and graph states, in particular, play indispensable roles in quantum network and quantum metrology. We demonstrate a semiconductor quantum dot based device in which the confined hole spin acts as a needle in a quantum knitting machine producing continuously and deterministically at sub-Gigahertz repetition rate single indistinguishable photons which are all polarization entangled to each other and to the spin in a one dimensional cluster state. By projecting two nonadjacent photons onto circular polarization bases we disentangle the spin from the photons emitted in between. This way we demonstrate a novel way for producing deterministic and continuous all-photonic cluster states. We use polarization tomography on four sequentially detected photons to demonstrate and to directly quantify the robustness of the cluster’s entanglement and the determinism in its photon generation.

Generation of gamma photons and pairs with transverse orbital angular momentum via spatiotemporal optical vortex pulse

We present the generation of well-collimated gamma photons and pairs with extrinsic transverse orbital angular momentum (TOAM) through the head-on collision of an intense spatiotemporal optical vortex (STOV) pulse carrying intrinsic TOAM and a high-energy electron beam. It is found that the TOAM of STOV pulse remains almost unchanged, and the TOAM is conserved in the center-of-mass frame. Moreover, there exhibits a duality for particles TOAM in the CMF and laboratory frame when the initial location of high-energy electron beam is different. Furthermore, the TOAM of gamma photons in the CMF increases while that of positrons decreases as the topological charge of STOV pulse increases, whereas in the LF, the TOAM of both gamma photons and positrons decreases. The result under the same pulse intensity is better than that under the same pulse energy. The increase in the initial energy of high-energy electrons leads to an enhancement of the TOAM of both gamma photons and positrons in both frames. Gamma photons and electrons/positrons with TOAM as a new degree of freedom may have extensive applications in optical communication, astrophysics, nanomaterials, and other fields.