Optical Gate Research Articles

Simultaneous Observation of the Cyclotron Resonances of Electrons and Holes in a HgTe/CdHgTe Double Quantum Well under “Optical Gate” Effect

Spectral studies of the photoconductivity in the temperature range of T = 5–70 K, as well as studies of the magneto-absorption and magnetotransport at T = 4.2 K, have been performed in a HgTe/CdHgTe heterostructure with a double quantum well under an “optical gate” effect. Studies of magneto-absorption spectra under the controlled optical exposure have made it possible to observe absorption lines caused by both the cyclotron resonances of electrons and holes simultaneously. The coexistence of electrons and holes in the HgTe/CdHgTe double quantum well with a relatively large bandgap (~80 meV) indicates the appearance of a strongly inhomogeneous light-induced distribution of charge carriers in the plane of the structure. Experimental results obtained clearly demonstrate disadvantages of the control of the Fermi level positions in heterostructures with HgTe/CdHgTe quantum wells by means of the optical gate.

Robust shortcut for controlling Bloch states in optical lattices

The ability to manipulate quantum states with robustness is crucial for various quantum applications, including quantum computation, quantum simulation, and quantum precision measurement. While pulsed shortcut techniques have proven effective for controlling bands and orbits in optical lattices, their robustness has not been extensively studied. In this paper, we present an improved shortcut design scheme that retains the advantages of high speed and high fidelity, while ensuring exceptional robustness. We conduct comprehensive experimental verifications to demonstrate the effectiveness of this new robust shortcut and its application in quantum gate design. The proposed scheme is expected to enhance the robustness of optical lattice orbit-based interferometry, quantum gates, and other processes.

Design of Ultrasmall Plasmonic Logic Gates Based on Single Nanoring Dielectric-Metal-Dielectric Waveguide

This paper proposes a new configuration of dielectric-metal-dielectric (DMD) waveguides to design optical logic gates. Seven plasmonic logic gates, including NOT, OR, AND, NAND, NOR, XOR, and XNOR, are realized by one nanoring and four DMD plasmonic waveguides. To realize the logic gates, an ultrasmall size of 300 nm × 300 nm device is designed. The performance of the plasmonic logic gates is based on constructive and deconstructive interference between input and control ports. To evaluate the logic state of the output port, the threshold transmission limit is assumed to be 0.35. The transmission ratio, T, contrast ratio, CR, modulation depth, MD, insertion loss, IL, and contrast loss, CL, parameters measure the seven logic gates’ performance. A maximum T of 232% is obtained for AND, OR, and XNOR logic gates. Simulation results show that the dimensional parameters are optimized because of very high MD for all seven logic gates. Maximum values of CR and CL are obtained for the NOT gate. For the AND gate, a minimum IL value is achieved. The studied plasmonic logic gates can be employed in building blocks of all-optical signal-processing nanocircuits and nanophotonics devices. The finite element method (FEM) simulates the structure with COMSOL Multiphysics 5.4 software.

Simple and reconfigurable all-optical logic gate

A photonics-based digital signal processing structure that has the ability to realise all the six basic logical operations, namely XOR, OR, AND, XNOR, NOR and NAND, is presented. It is based on applying the two digital inputs into a dual-polarisation modulator and adjusting the angle of a waveplate connected to the modulator output to realise different logical operations. The proposed dual-polarisation modulator based optical logic gate has a simple and compact structure and robust performance. Switching between different logical operations can be realised in high speed by adjusting only one system parameter, with no change in the system physical configuration. The proposed dual-polarisation modulator based optical logic gate is theoretically analysed. Using the system parameter setting obtained from the theoretical analysis, the six basic logical operations are experimentally demonstrated. To our knowledge, this is the first report of an optical logic gate that is capable of switching between all the six basic logical operations by adjusting only one system parameter.

Simulation of universal optical logic gates under energy sharing collisions of Manakov solitons and fulfillment of practical optical logic criteria.

The universal optical logic gates, namely, nand and nor gates, have been theoretically simulated by employing the energy sharing collision of bright optical solitons in the Manakov system, governing pulse propagation in a highly birefringent fiber. Further, we also realize the two-input optical logic gates, such as and, or, xor, xnor, for completeness of our scheme. Interestingly, our idea behind the simulation naturally satisfies all the criteria for practical optical logic, which in turn displays the strength and versatility of our theoretical simulation of universal optical logic gates. Hence, our approach paves the way for the experimentalists to create a new avenue in this direction if the energy sharing collisions of Manakov solitons are experimentally realized in the future.

Ultrafast snapshots of terahertz electric potentials across ring-shaped quantum barriers

Abstract Probing the time evolution of the terahertz electric field within subwavelength dimensions plays a crucial role in observing the nanoscale lightwave interactions with fundamental excitations in condensed-matter systems and in artificial structures, such as metamaterials. Here, we propose a novel probing method for measuring terahertz electric potentials across nanogaps using a combination of optical and terahertz pulse excitations. To achieve this, we employ ring-shaped nanogaps that enclose a metallic island, allowing us to capture tunneling charges when subjected to terahertz electromagnetic pulse illumination. By controlling and manipulating the terahertz tunneling charges through a focused optical gate pulse, we can obtain the terahertz potential strength as a function of spatial coordinates and time delays between pulses. To accurately quantify the time evolution of terahertz electric potential across quantum barriers, we carefully calibrate the recorded nonlinear tunneling current. Its on-resonance and off-resonance behaviors are also discussed, providing valuable insights into the antenna’s characteristics and performance.

A versatile device for implementing the optical quantum gates in multiple degrees of freedom

Optical quantum logic gates are the basic elements for building optical quantum computer. Usually, to implement different logic gates, different optical elements and frameworks are needed. Here, we propose a versatile device that a modified Sagnac interferometer composed of a spatial light modulator (SLM) for implementing multiple optical gates within a classical light framework. We demonstrate that the device can manipulate the polarization and full-field spatial modes of photons to perform multi-qubit logic operations. And versatile conversions between different logic gates are achieved by simply altering the hologram imposed on SLM. Our device shows a good performance in exploring the photon’s full degrees of freedom, which makes it an appropriate candidate for integrated optical computing.

Achieving Ultralong Room-Temperature Phosphorescence in Two-Dimensional Metal Halide Perovskites by Alkyl Chain Engineering.

Two-dimensional (2D) metal halide perovskites with highly efficient ultralong room-temperature phosphorescence (URTP) are rare due to their uncertain structures and complicated intermolecular interactions. Herein, by varying the alkyl length of organic units, we synthesized two single-component 2D metal hybrid perovskites, i.e., B-MACC and B-EACC, with obvious URTP emission. In particular, B-EACC exhibits a green-yellow URTP emission with an ultralong lifetime (579 ms) and a high efficiency (14.86%). It is found that the molecular packing of B-EA+ cations because of the presence one more carbon in the alkyl chain affords strong hydrogen bonding and π-π stacking interactions, which immobilizes and reduces the triplet exciton quenching. Moreover, B-MACC and B-EACC with space-time dual-resolved characteristics can be utilized for dynamic information encryption and optical logic gate applications. This study is the first to disclose the relation between the characteristics of molecular packing and the resultant URTP of 2D metal hybrid perovskites, significantly advancing the development of next-generation URTP materials for versatile applications.

Femtosecond Optical Kerr Gate in tissues.

The Optical Kerr Effect is investigated for the first time in biological tissues. This nonlinear effect was explored in both human brain and avian breast tissues using a time-resolved femtosecond pump-probe Optical Kerr Gate that looks for phase changes that arise in the probe from the pump induced Kerr refractive index change. The tissue samples produced a unique ultrafast (700-800 fs) doubled peaked temporal signal, which is indicative of interplay between the different ultrafast mechanisms (electronic plasma and molecular) that make up the Kerr index. The unique profile was replicated in theoretical simulations. The properties of the temporal profile varied between samples suggesting that it could be used as a new diagnostic. Understanding this behavior can help improve the scientific understanding of nonlinear spectral diagnostic techniques and potentially create a new Kerr-based optical biopsy method.

Two-dimensional photonic crystal based optical CNOT gate

Two-dimensional photonic crystal based optical CNOT gate

One‐dimensional molecular co‐crystal alloys capable of full‐color emission for low‐loss optical waveguide and optical logic gate

AbstractThe luminescence color of molecule‐based photoactive materials is the key to the applications in lighting and optical communication. Realizing continuous regulation of emission color in molecular systems is highly desirable but still remains a challenge due to the individual emission band of purely organic molecules. Herein, a novel alloy strategy based on molecular co‐crystals is reported. By adjusting the molar ratio of pyrene (Py) and fluorathene (Flu), three types of molecular co‐crystal alloys (MCAs) assemblies are prepared involving Py‐Flu‐OFN‐x%, Py‐Flu‐TFP‐x%, Py‐Flu‐TCNB‐x%. Multiple energy level structure and Förster resonance energy transfer (FRET) process endow materials with tunable full‐spectra emission color in visible region. Impressively, these MCAs and co‐crystals can be successfully applied to low optical loss waveguide and optical logic gate by virtue of all‐color luminescence from blue across green to red, together with smooth surface of one‐dimensional microrods, which show promising applications as continuous light emitters for advance photonics applications.

Realizing efficient emission and triple‐mode photoluminescence switching in air‐stable tin(IV)‐based metal halides via antimony doping and rational structural modulation

AbstractRecently, many lead‐free metal halides with diverse structures and highly efficient emission have been reported. However, their poor stability and single‐mode emission color severely limit their applications. Herein, three homologous Sb3+‐doped zero‐dimensional (0D) air‐stable Sn(IV)‐based metal halides with different crystal structures were developed by inserting a single organic ligand into SnCl4 lattice, which brings different optical properties. Under photoexcitation, (C25H22P)SnCl5@Sb·CH4O (Sb3+−1) does not emit light, (C25H22P)2SnCl6@Sb‐α (Sb3+−2α) shines bright yellow emission with a photoluminescence quantum yield (PLQY) of 92%, and (C25H22P)2SnCl6@Sb‐β (Sb3+−2β) exhibits intense red emission with a PLQY of 78%. The above three compounds show quite different optical properties should be due to their different crystal structures and the lattice distortions. Particularly, Sb3+−1 can be successfully converted into Sb3+−2α under the treatment of C25H22PCl solution, accompanied by a transition from nonemission to efficient yellow emission, serving as a “turn‐on” photoluminescence (PL) switching. Parallelly, a reversible structure conversion between Sb3+−2α and Sb3+−2β was witnessed after dichloromethane or volatilization treatment, accompanied by yellow and red emission switching. Thereby, a triple‐mode tunable PL switching of off–onI–onII can be constructed in Sb3+‐doped Sn(IV)‐based compounds. Finally, we demonstrated the as‐synthesized compounds in fluorescent anticounterfeiting, information encryption, and optical logic gates.

Quantum optical tristate Toffoli gate using frequency encoding principle of light with semiconductor optical amplifier

Quantum optical tristate Toffoli gate using frequency encoding principle of light with semiconductor optical amplifier

Intensity-Dependent Optical Response of 2D LTMDs Suspensions: From Thermal to Electronic Nonlinearities.

The nonlinear optical (NLO) response of photonic materials plays an important role in the understanding of light-matter interaction as well as pointing out a diversity of photonic and optoelectronic applications. Among the recently studied materials, 2D-LTMDs (bi-dimensional layered transition metal dichalcogenides) have appeared as a beyond-graphene nanomaterial with semiconducting and metallic optical properties. In this article, we review most of our work in studies of the NLO response of a series of 2D-LTMDs nanomaterials in suspension, using six different NLO techniques, namely hyper Rayleigh scattering, Z-scan, photoacoustic Z-scan, optical Kerr gate, and spatial self-phase modulation, besides the Fourier transform nonlinear optics technique, to infer the nonlinear optical response of semiconducting MoS2, MoSe2, MoTe2, WS2, semimetallic WTe2, ZrTe2, and metallic NbS2 and NbSe2. The nonlinear optical response from a thermal to non-thermal origin was studied, and the nonlinear refraction index and nonlinear absorption coefficient, where present, were measured. Theoretical support was given to explain the origin of the nonlinear responses, which is very dependent on the spectro-temporal regime of the optical source employed in the studies.

Intrinsic photomixing detector based on amorphous silicon for envelope mixing of optical signals

In this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defect-induced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.

Encryption Using Optical Pseudo-Random Binary Sequence Based on Optical Logic Gate

In this paper, we propose a scheme for high-speed all-optical Pseudo-Random Binary Sequence (PRBS) generator and use it for generating keystream for encryption. This PRBS generator design is based on Linear Feedback Shift Registers (LFSR) and optical XOR and AND gates. The optical logical gates are based on quantum dot-semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA-MZI). With two photon absorption (TPA) in quantum dot-semiconductor optical amplifier (QD-SOA), this kind of optical logic gates performs well when processing data in an ultra-fast timescale and therefore able to function as high speed PRBS generator. Result shows that it’s possible for this scheme to realize all-optical encryption and decryption at high process rate up to 320 Gb/s. We simulated different ways of generating keystream with schemes such as cascaded generator, parallel generator and alternating step generator. These generators use more than one LFSR. Result shows that the schemes we use can function as stable and complex keystream generators.

Investigations of all-optical gates based on linear photonic crystals using the PSK technique and beam interference effect

ABSTRACT In this paper, all optical OR, AND, NOR and NAND gates based on linear photonic crystals (LPhCs) have been numerically designed and simulated by the plane wave expansion (PWE) and finite difference time domain (FDTD) methods. The LPhC fundamental structure with cross-section of 114 is used for designing the proposed all optical gates (AOGATEs), which is composed of 15 × 23 cubic matrix of dielectric silicon rods in air substrate. The mechanism of the proposed AOGATEs is performed based on phase shift keying (PSK) technique and beam interference effect. Simulation results by FDTD approach illustrate the minimum contrast ratio of 8.88 and 10.31 dB for all optical AND/NOR and OR/NAND logic gates, respectively. Also, the minimum bit rate is obtained as 3.34 Tb/s for AND/NOR and 5 Tb/s for OR/NAND logic gates.

Simulation and Numerical Analysis of SOA Based All Optical NAND Gate for High Data Rate Communication

As a result of the development of advanced semiconductor-based optical switching devices and their commercialization, concepts and technologies in all-optical signal processing have evolved significantly in the past few years. In order to realize logical operations in photonic computing, universal gates are needed. In this research, the simple and compact all-optical NAND gate was designed using SOA and simulated at a high data rate of 10Gbps to 40 Gbps. The performance of the proposed NAND gate is shown by the numerical analysis for various input combinations and SOA. By changing wavelengths, injection currents, confinement factors, as well as optical components such as sources, amplifiers, and filters, a numerical analysis is performed. Unique results were obtained at a 10 Gbps data rate for NRZ-L user-defined bit sequences. This kind of all-optical NAND gate will be the perfect alternative in the field of optical computing to realize a high-speed optical communication network. An extinction ratio of 11.48 dB is achieved at a high-speed data rate of 10 Gbps to 40Gbps. The output spectrum of the designed NAND logic is also received for a wide input spectrum and the system responds selectively for the input wavelength at 1548.3 nm which is the probe signal wavelength.

Self-Assembled π-Conjugated Organic/Polymeric Microresonators and Microlasers

Optical microresonators are minute dielectric objects that are utilized as essential components in micrometer-scale light and laser sources, optical integrated circuits, micro-displays, chemo- and biosensors, and so forth. Particularly, microresonators made from organic and polymeric materials find unique applications owing to its structural flexibility, color tunability, and functionality with simple fabrication process, low cost and low energy consumption. In this Account, we highlight our recent progress on the organic/polymeric microresonators made through precisely controlled self-assembly process. The microstructures display novel optical functions such as circularly polarized luminescence emission, lasers, light energy harvesters, optical gate operations, optical memories and authentications, and optical sensing for environmental changes and mechanical forces. Our methodology for the precise design and control of organic and polymeric microstructures, will bridge between nanometer-scale supramolecular chemistry and bulk materials and will pave the way toward flexible optical and laser applications. Precise control of microstructures by self-assembly of π-conjugated organic molecules and polymers offers materials with sophisticated optical functions such as optical resonators and lasers, circularly polarized luminescence emitters, optical logic gate operations, optical memories, and light energy harvesting, which are utilized as optical sensors for environmental changes and mechanical forces.

Transient optical properties, laser induced avalanche effect, and all optical switching in molecular aggregates

Organic dyes have attracted expressive research interest in recent years due to their wide range of applications. Self-aggregation occurs in a variety of organic molecules, a phenomenon that changes the photochemical and photophysical properties of dyes. Laser beams with wavelengths of 663 nm and 532 nm were used for thermal modulation of the aggregation states of the methylene blue dye, which led to the discovery of a novel avalanche phenomena in the molecular/supramolecular level and observations of not yet reported material optical behaviors. The obtained experimental data reveals the existence of asymmetric optical responses of aggregated dyes under laser excitation with wavelengths at the monomer or at the dimer absorption bands. The observed optical behaviors, resulting from the laser modulation of the molecular aggregation states, may find applications in the field of organic electronics and devices, such as optical logical gates and optical power limiters. A dual mechanism all optical switching driven by the simultaneous action of the cooperative effects of the laser induced disruption of dimeric dye units and thermal lensing was achieved.