All-optical Generation Research Articles

All-optical generation of full-range symmetry-tunable triangular-shaped pulses via wavelength multiplexing

A novel, to the best of our knowledge, all-optical approach for generating full-range symmetry-tunable triangular-shaped pulses through wavelength multiplexing is proposed and experimentally demonstrated. Two light-waves with a specified wavelength interval are injected in parallel into two commercial push–pull Mach–Zehnder modulators (MZMs) to carry the baseband radio frequency input. A tunable optical delay line (ODL) followed by one MZM is utilized to introduce the desired phase shift. By multiplexing the modulated signals carried on two wavelengths, triangular-shaped pulses can be achieved by the opto-electronic conversion. In this approach, by simply adjusting the DC bias voltages and the delay time offered by ODL, the triangular-shaped pulse with any self-defined symmetrical coefficient can be obtained. A complete theoretical analysis on the operation principle is presented and verified. The triangular-shaped pulses with full-range tunable symmetrical coefficients at the repetition rate of 5 GHz are successfully generated. This approach features all-optical architecture, ultra-wide system bandwidth, full-range tunable symmetry (0%–100%) and excellent reconfigurability, which are highly desired for the high-performance triangular-shaped pulse generator.

All-optical generation of structured light beams via microwave-field-controlled electromagnetically induced transparency

All-optical generation of structured light beams via microwave-field-controlled electromagnetically induced transparency

All-Optical 4-Bit Parity Generator and Checker Utilizing Carrier Reservoir Semiconductor Optical Amplifiers

All-Optical 4-Bit Parity Generator and Checker Utilizing Carrier Reservoir Semiconductor Optical Amplifiers

Design and performance analysis of 2D photonic crystal-based all-optical parity generator and checker

Design and performance analysis of 2D photonic crystal-based all-optical parity generator and checker

Ultrafast Plasmonics for All-Optical Switching and Pulsed Lasers

Surface plasmon resonances (SPRs) are often regarded as the collective oscillations of charge carriers localized at the dielectric–metal interface that display an ultrafast response upon light excitation. The recent developments in the fabrication and characterization of plasmonic nanostructures have stimulated continuous effects in the search for their potential applications in the photonic fields. Concentrating on the role of plasmonics in photonics, this review covers recent advances in ultrafast plasmonic materials with a prime focus on all-optical switching. Fundamental phenomena of plasmonic light–matter interaction and plasmon dynamics are discussed by elaborating on the ultrafast processes unraveled by both experimental and theoretical methods, along with a comprehensive illustration of leveraging ultrafast plasmonics for all-optical switching and pulse laser generation with a focus on device design and performance. This review is concluded with a brief highlight of the current progress and the potential future directions in ultrafast plasmonics.

Graph-theoretical optimization of fusion-based graph state generation

Graph states are versatile resources for various quantum information processing tasks, including measurement-based quantum computing and quantum repeaters. Although the type-II fusion gate enables all-optical generation of graph states by combining small graph states, its non-deterministic nature hinders the efficient generation of large graph states. In this work, we present a graph-theoretical strategy to effectively optimize fusion-based generation of any given graph state, along with a Python package OptGraphState. Our strategy comprises three stages: simplifying the target graph state, building a fusion network, and determining the order of fusions. Utilizing this proposed method, we evaluate the resource overheads of random graphs and various well-known graphs. Additionally, we investigate the success probability of graph state generation given a restricted number of available resource states. We expect that our strategy and software will assist researchers in developing and assessing experimentally viable schemes that use photonic graph states.

Design of RSOA-based all-optical parity generator and checker

Design of RSOA-based all-optical parity generator and checker

All-optical generation, detection, and manipulation of picosecond acoustic pulses in 2D semiconductor/dielectric heterostructures

Launching, tracking, and controlling picosecond acoustic (PA) pulses are fundamentally important for the construction of ultrafast hypersonic wave sources, ultrafast manipulation of matter, and spatiotemporal imaging of interfaces. Here, we show that GHz PA pulses can be all-optically generated, detected, and manipulated in a 2D layered MoS2/glass heterostructure using femtosecond laser pump–probe. Based on an interferometric model, PA pulse signals in glass are successfully decoupled from the coexisting temperature and photocarrier relaxation and coherent acoustic phonon (CAP) oscillation signals of MoS2 lattice in both time and frequency domains. Under selective interface excitations, temperature-mediated interfacial phonon scatterings can compress PA pulse widths by about 50%. By increasing the pump fluences, anharmonic CAP oscillations of MoS2 lattice are initiated. As a result, the increased interatomic distance at the MoS2/glass interface that reduces interfacial energy couplings can markedly broaden the PA pulse widths by about 150%. Our results open new avenues to obtain controllable PA pulses in 2D semiconductor/dielectric heterostructures with femtosecond laser pump–probe, which will enable many investigations and applications.

5-bit all-optical quantum random number generator based on a time-multiplexed optical parametric oscillator.

Random numbers are of critical importance in many applications, including secure communication, photonics computing and cryptography. Due to the non-deterministic nature of the quantum processes, a degenerate optical parametric oscillator (DOPO) constitutes a solution to produce true randomness. Nevertheless, one of the existing challenges for DOPO in this field is bit sequence scalability. Here, we experimentally report on the generation of 5-bit random number streams in a time-multiplexed femtosecond DOPO system. A multi-pass cell is added to elongate the OPO cavity to scale up the bit sequences. To this end, for a ∼15 m long all free space OPO cavity, resonating 5 signal pulses with a repetition rate of 50 MHz is demonstrated. The above-threshold binary phase nature originates from vacuum fluctuations of a DOPO ensuring the randomness of the system. The phase state of the output is characterized by the interference pattern between the output pulses and the fundamental pump pulses. Different bit sequences are presented here by turning on and off the OPO. Conditional probability is performed to verify the randomness of the output for 1200 bits. Our scheme provides a new direction for an all-optical random number generator.

All-optical spatiotemporal mapping of ROS dynamics across mitochondrial microdomains in situ

Hydrogen peroxide (H2O2) functions as a second messenger to signal metabolic distress through highly compartmentalized production in mitochondria. The dynamics of reactive oxygen species (ROS) generation and diffusion between mitochondrial compartments and into the cytosol govern oxidative stress responses and pathology, though these processes remain poorly understood. Here, we couple the H2O2 biosensor, HyPer7, with optogenetic stimulation of the ROS-generating protein KillerRed targeted into multiple mitochondrial microdomains. Single mitochondrial photogeneration of H2O2 demonstrates the spatiotemporal dynamics of ROS diffusion and transient hyperfusion of mitochondria due to ROS. This transient hyperfusion phenotype required mitochondrial fusion but not fission machinery. Measurement of microdomain-specific H2O2 diffusion kinetics reveals directionally selective diffusion through mitochondrial microdomains. All-optical generation and detection of physiologically-relevant concentrations of H2O2 between mitochondrial compartments provide a map of mitochondrial H2O2 diffusion dynamics in situ as a framework to understand the role of ROS in health and disease.

All-optical generation of static electric field in a single metal-semiconductor nanoantenna

Electric field is a powerful instrument in nanoscale engineering, providing wide functionalities for control in various optical and solid-state nanodevices. The development of a single optically resonant nanostructure operating with a charge-induced electrical field is challenging, but it could be extremely useful for novel nanophotonic horizons. Here, we show a resonant metal-semiconductor nanostructure with a static electric field created at the interface between its components by charge carriers generated via femtosecond laser irradiation. We study this field experimentally, probing it by second-harmonic generation signal, which, in our system, is time-dependent and has a non-quadratic signal/excitation power dependence. The developed numerical models reveal the influence of the optically induced static electric field on the second harmonic generation signal. We also show how metal work function and silicon surface defect density for different charge carrier concentrations affect the formation of this field. We estimate the value of optically-generated static electric field in this nanoantenna to achieve ≈108V/m. These findings pave the way for the creation of nanoantenna-based optical memory, programmable logic and neuromorphic devices.

Kerr effect based optical switching for the assessment of all-optical sequence generator and decoder circuits

Abstract The sequence generator and decoders are used for noise analysis, signal propagation, data processing, and bit error rate analysis. The semiconductor and modern electronic components are facing challenges in terms of processing speed and data rates. However, by using photons rather than electrons as the information carriers, these difficulties can be reduced. Photonic devices attained the operating speed in the regime of terahertz, but sit back due to the diffraction limit, which can be overcome by employing plasmon-based devices or all-optical devices. This work presents a numerical investigation of metal-insulator-metal (MIM) plasmonic waveguides based two-bit sequence generator (SG) and decoder. The structure of SG and decoder circuits are designed within the footprints of 86 × 9 and 140 × 9 µm, by cascading one power splitter (PS) and four Mach-Zehnder interferometers (MZIs), and two PS and five MZI, respectively. To design the MZI, the optimization of the S-bend waveguide, the coupling length of the power splitter, and the length of the interferometric arm are done by recording the output power. The highest extinction ratio of 22.1 dB is attained at the coupling and interferometric arm lengths of 1.5 µm and 5 µm, respectively. The propagation of the optical signal through the structure of SG is observed by using a two-dimensional finite difference time domain method-based tool.

Quantum vortices of strongly interacting photons

Vortices are topologically nontrivial defects that generally originate from nonlinear field dynamics. All-optical generation of photonic vortices—phase singularities of the electromagnetic field—requires sufficiently strong nonlinearity that is typically achieved in the classical optics regime. We report on the realization of quantum vortices of photons that result from a strong photon-photon interaction in a quantum nonlinear optical medium. The interaction causes faster phase accumulation for copropagating photons, producing a quantum vortex-antivortex pair within the two-photon wave function. For three photons, the formation of vortex lines and a central vortex ring confirms the existence of a genuine three-photon interaction. The wave function topology, governed by two- and three-photon bound states, imposes a conditional phase shift of π per photon, a potential resource for deterministic quantum logic operations.

Random number generation using spontaneous symmetry breaking in a Kerr resonator.

We demonstrate an all-optical random number generator based on spontaneous symmetry breaking in a coherently driven Kerr resonator. Random bit sequences are generated by repeatedly tuning a control parameter across a symmetry-breaking bifurcation that enacts random selection between two possible steady-states of the system. Experiments are performed in a fiber ring resonator, where the two symmetry-broken steady-states are associated with orthogonal polarization modes. Detrimental biases due to system asymmetries are suppressed by leveraging a recently discovered self-symmetrization phenomenon that ensures the symmetry-breaking dynamics act as an unbiased coin toss, with a genuinely random selection between the two available steady-states. We optically generate bits at a rate of 3 MHz without post-processing and verify their randomness using the National Institute of Standards and Technology and Dieharder statistical test suites.

Terahertz-driven positron acceleration assisted by ultra-intense lasers.

Generation and acceleration of energetic positrons based on laser plasma have attracted intense attention due to their potential applications in medical physics, high energy physics, astrophysics and nuclear physics. However, such compact positron sources face a series of challenges including the beam dispersion, dephasing and unstability. Here, we propose a scheme that couples the all-optical generation of electron-positron pairs and rapid acceleration of copious positrons in the terahertz (THz) field. In the scheme, nanocoulomb-scale electrons are first captured in the wakefield and accelerated to 2.5 GeV. Then these energetic electrons emit strong THz radiation when they go through an aluminum foil. Subsequently, abundant γ photons and positrons are generated during the collision of GeV electron beam and the scattering laser. Due to the strong longitudinal acceleration field and the transvers confining field of the emitted THz wave, the positrons can be efficiently accelerated to 800 MeV, with the peak beam brilliance of 2.26 × 1012s-1mm-2mrad-2eV-1. This can arouse potential research interests from PW-class laser facilities together with a GeV electron beamline.

Nonlinear All-Optical Coherent Generation and Read-Out of Valleys in Atomically Thin Semiconductors.

With conventional electronics reaching performance and size boundaries, all-optical processes have emerged as ideal building blocks for high speed and low power consumption devices. A promising approach in this direction is provided by valleytronics in atomically thin semiconductors, where light-matter interaction allows to write, store, and read binary information into the two energetically degenerate but non-equivalent valleys. Here, nonlinear valleytronics in monolayer WSe2 is investigated and show that an individual ultrashort pulse with a photon energy tuned to half of the optical band-gap can be used to simultaneously excite (by coherent optical Stark shift) and detect (by a rotation in the polarization of the emitted second harmonic) the valley population.

Nanomechanics with plasmonic nanoantennas: ultrafast and local exchange between electromagnetic and mechanical energy

Converted into mechanical nanoresonators after optical pulsed excitation and electron decay into coherent acoustic phonons, plasmonic nanoantennas produce a periodic modulation of their optical properties, allowing, in turn, an optical reading of these extremely small movements. In this work, we review the physics of these nanoresonators and their acoustic vibrations, whose frequencies are in the range of a few to tens of GHz. The accurate determination of their oscillation frequencies allows them to act as mechanical nanoprobes, measure local mechanical moduli of the environment, and perform high-resolution imaging using phononic reconstruction. Furthermore, the internal and external damping mechanisms that affect the quality factor of the nanoresonator and, in particular, the role of the substrate when the nanoantennas are integrated into platforms and probed individually are also reviewed. Finally, we discuss the all-optical generation of hypersonic surface acoustic waves with nanoantennas and the importance of their manipulation for potential acousto-plasmonic devices operating in the GHz range and at nanoscale.

Generation of intense magnetic wakes by relativistic laser pulses in plasma

The emergence of petawatt lasers focused to relativistic intensities enables all-optical laboratory generation of intense magnetic fields in plasmas, which are of great interest due to their ubiquity in astrophysical phenomena. In this work, we study generation of spatially extended and long-lived intense magnetic fields. We show that such magnetic fields, scaling up to the gigagauss range, can be generated by interaction of petawatt laser pulses with relativistically underdense plasma. With three-dimensional particle-in-cell simulations we investigate generation of magnetic fields with strengths up to 10^{10} G and perform a large multi-parametric study of magnetic field in dependence on dimensionless laser amplitude a_{0} and normalized plasma density n_{e}/n_{c}. The numerical results yield scaling laws that closely follow derived analytical result B propto sqrt{a_{0}n_{e}/n_{c}}, and further show a close match with previous experimental works. Furthermore, we show in three-dimensional geometry that the decay of the magnetic wake is governed by current filament bending instability, which develops similarly to von Kármán vortex street in its nonlinear stage.

Photonic crystal based design of a 3-bit all-optical parity checker and generator for all-optical computing.

Photonic crystal based designs of 3-bit even parity checker and generator circuits are proposed in this paper. These circuits are realized for the first time, to the best of our knowledge, on a photonic crystal platform with the aim of achieving power efficient, simple, and compact devices suitable for photonic integrated circuits. The proposed structures are realized using all-optical reconfigurable XOR/NOT gates with compact dimensions, low power consumption, and high contrast ratios. The operation is based on a linear interference effect leading to reduced power consumptions feasible for operation in the telecommunication wavelength of 1550nm. The various performance metrics such as contrast ratio, response time, and data rate are analyzed based on simulations using the finite difference time domain technique. All structures achieve small footprints and low response times with operation speeds up to 1 Tbps. The designs are based purely on silicon material, which enables ease of fabrication and offers easy compatibility with existing opto-electronic systems as well as with upcoming all-optical systems. The above circuits have wide applications in optical computing, error correction, detection, and optical cryptography.

Analysis of All-Optical Generation of Graphene Surface Plasmons by a Frequency-Difference Process

The generation of graphene surface plasmons (SPs) by a frequency-difference nonlinear (NL) process caused by the interaction of two optical beams was experimentally demonstrated several years ago by measuring the differential reflectance of the probe beam. However, the understanding of these results requires much larger second-order optical conductivities of graphene than calculations performed so far can yield. In this work, we carefully calculate the relevant NL conductivities and show that, indeed, the experimental observations of the differential reflectance must have originated from physical processes beyond the coherent frequency-difference generation of SPs described by the density-matrix perturbation theory approach, presumably by hot-electron effects. We also suggest an alternative way of detecting optically generated SPs, which can be feasible at lower powers of the optical pulses. Such additional experiments are expected to help understand the remaining discrepancy between the theory and the existing experimental data.