In this study, all-optical OR, exclusive OR (XOR), NOR, XNOR, AND, NAND, and NOT logic gates using metalinsulator-metal (MIM) waveguides with a rectangular ring resonator are designed and analyzed. The structure has a...
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In this study, all-optical OR, exclusive OR (XOR), NOR, XNOR, AND, NAND, and NOT logic gates using metalinsulator-metal (MIM) waveguides with a rectangular ring resonator are designed and analyzed. The structure has a silver plate with three input waveguides, one output waveguide, and a rectangular ring resonator. One of the input ports is used as a control port. The finite-difference time-domain (FDTD) method is utilized to obtain the optical spectrum of the proposed structures. To realize all-optical logic gate properties of the designed structures, optical signals with the same phase or different phases are passed through the waveguides. Transmission spectrum (T), contrast ratio (CR), and modulation depth (MD) parameters are obtained to determine the performances of all-optical logic gates. To determine the logic 1 (ON) and logic 0 (OFF) states of the output ports, the threshold transmission value is accepted as 0.23 for all-optical logic gates. For the proposed designs, the highest transmission, contrast ratio, and modulation depth values are 217%, 6.75 dB, and 100%, respectively. The structure also supports a data rate of 24 Tb/s. The designed optical logic gates have valuable features for developing high-performance optical devices.
Resonant mode conversions in partially parity-time (PT)-symmetric multimode waveguides are investigated. First, the symmetry breaking and degeneracy splitting of linear eigenmodes are found numerically and analyticall...
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Resonant mode conversions in partially parity-time (PT)-symmetric multimode waveguides are investigated. First, the symmetry breaking and degeneracy splitting of linear eigenmodes are found numerically and analytically. Moreover, mode conversions in the nonconservative system are demonstrated using longitudinally periodic modulation of the complex refractive index. The results show that, under the resonance condition, conversions between the unbroken modes with the same topological charge can occur, with conversion frequency being presented analytically. Finally, the influence of nonlinear effects on the resonant mode conversions is also discussed. It is found that the mode conversions depend on the dynamic equilibrium of the modes in nonlinear media, resulting in the conversions between the quadrupole modes in self-focusing medium, and the basic modes with ring structure in defocusing medium can be achieved. These results are beneficial for our further understanding of mode conversions in complex waveguides and can be applied to manipulation of the optical beam.
Off-axis twisted waveguides possess unique optical properties such as circular and orbital angular momentum (OAM) birefringence, setting them apart from their straight counterparts. Analyzing mode formation in such he...
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Off-axis twisted waveguides possess unique optical properties such as circular and orbital angular momentum (OAM) birefringence, setting them apart from their straight counterparts. Analyzing mode formation in such helical waveguides relies on the use of specific coordinate frames that follow the twist of the structure. In this paper, the differences between modes forming in high-contrast off-axis twisted waveguides defined in the three most important coordinate systems—the Frenet-Serret, the helicoidal, or the Overfelt frame—are investigated through numerical simulations. We explore modal characteristics up to high twist rates (pitch: 50µm) and clarify a transformation allowing us to map the modal fields and the effective index back to the laboratory frame. In case the waveguide is single-mode, the fundamental modes of the three types of waveguides show significant differences in terms of birefringence, propagation loss, and polarization. Conversely, the modal characteristics of the investigated waveguides are comparable in the multimode domain. Furthermore, our paper examines the impact of twisting on spatial mode properties. At high twist rates, a separation of modes with different spins is observed, suggesting a potential influence of the photonic spin Hall effect. Additionally, twisting induces OAM-dependent changes in the intensity distribution, indicating the presence of the photonic orbital Hall effect. Lastly, modes of single-mode helical waveguides were found to exhibit superchiral fields on their surfaces. These findings provide a comprehensive basis for further research into the physics of twisted off-axis waveguides. Implementation approaches such as 3D nanoprinting or fiber-preform twisting open the doors to potential applications of such highly twisted waveguides, including chip-integrated devices for broadband spin- and OAM-preserving optical signal transport, as well as applications in chiral spectroscopy or nonlinear frequency conversion.
The competition to suggest high performance solutions for terahertz communication targets 0.22-0.32 THz band because of its bandwidth and attenuation advantages over other terahertz frequencies. However, the state-of-...
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ISBN:
(纸本)9781510651456;9781510651449
The competition to suggest high performance solutions for terahertz communication targets 0.22-0.32 THz band because of its bandwidth and attenuation advantages over other terahertz frequencies. However, the state-of-the-art suffers from conventional terahertz waveguide performance. Alternatively, the spoof surface plasmon polariton waveguides (SSPP WGs) measurements achieve the record-low insertion loss per unit length at 0.3 THz. On the other hand, the SSPP WGs require high performance transitions to interface with terahertz active devices such as transistors and diodes. In this paper, we present design, optimization, and experimental verification of high-performance coplanar waveguide-to-SSPP WG (CPW-to-SSPP WG) transitions at 0.25-0.3 THz band. The measurements show that the insertion loss of a CPW to SSPP WG transition can be suppressed up to -0.5 dB at the proposed frequency band.
Multimode interference couplers were fabricated from tantalum pentoxide thin film grown with electron beam evaporation routes. The large Kerr nonlinearity enabled experimental demonstration of a low-power optically co...
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Multimode interference couplers were fabricated from tantalum pentoxide thin film grown with electron beam evaporation routes. The large Kerr nonlinearity enabled experimental demonstration of a low-power optically controlled Y-junction device based on a nonlinear MMI coupler that was 8 mu m wide, 100 nm thick, and 4.3 mm long. The nonlinear switching experiments were comparable to numerical simulations based on the temporal evolution with nonlinear coupled mode equations including self-phase modulation, cross-phase modulation, four-wave mixing, and dispersions. The demonstration suggests a promising platform for nonlinear integrated photonic functional devices such as saturation absorbers and optical power limiters in addition to the demonstrated all-optical switches.
In the silicon-based devices, the third-order nonlinear effects containing Kerr effects, two-photon absorption (TPA), free carrier absorption (FCA) and free carrier dispersion (FCD) play the important role in the phys...
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ISBN:
(纸本)9781510662261;9781510662278
In the silicon-based devices, the third-order nonlinear effects containing Kerr effects, two-photon absorption (TPA), free carrier absorption (FCA) and free carrier dispersion (FCD) play the important role in the physical characteristics. In this paper, taking consideration of the linear and nonlinear effects, a comprehensive numerical analysis model based on the finite-difference-time-domain (FDTD) method is built and demonstrated. The nonlinear characteristics of the silicon-based waveguides and microring resonators are further discussed in the simulated results. The proposed model might provide an effective analysis method for all silicon-based devices, due to its good compatibility and accuracy.
We propose an unsupervised deep learning model based on physics-informed neural network (PINNS) to find the effective refractive index of a slab waveguide. The model accuracy could reach 99% within a time range from 6...
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ISBN:
(数字)9781665453011
ISBN:
(纸本)9781665453011
We propose an unsupervised deep learning model based on physics-informed neural network (PINNS) to find the effective refractive index of a slab waveguide. The model accuracy could reach 99% within a time range from 60 to 120 seconds for symmetric and anti-symmetric waveguide. The results show the success of the introduced method in solving fail cases of the compared methods.
Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with ...
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Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III-V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800 similar to 2400 nm, covering the operating wavelengths of III-V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of similar to 90% near the single-mode limit was obtained, and a low bending loss of similar to 0.01 dB was effectively achieved with the bending radius reaching 90 mu m, 70 mu m, and 40 mu m for wavelengths of 2000 nm, 1550 nm, and 850 nm, respectively. Furthermore, the use of a pedestal structure or a SiO2 bottom cladding layer has shown potential to further reduce bending losses. The introduction of a SiO2 bottom cladding layer effectively eliminates the influence of the substrate's larger refractive index, resulting in further improvement in waveguide performance. The platform enables tightly built waveguides and small bending radii with high field confinement and low propagation losses, showcasing silicon nitride waveguides on sapphire as promising passive components for the development of high-performance and cost-effective PICs.
The authors report a ductile dicing process for manufacturing optical-quality facets in a multi-layered silicon nitride platform without the need for polishing. A surface roughness (Sa) of 1.5 nm was achieved. This te...
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The authors report a ductile dicing process for manufacturing optical-quality facets in a multi-layered silicon nitride platform without the need for polishing. A surface roughness (Sa) of 1.5 nm was achieved. This technique was extended to fabricate ridge waveguides, and the results and characterization are reported. The authors report a ductile dicing process for manufacturing optical-quality facets in a multi-layered silicon nitride platform without the need for polishing. This technique was extended to fabricate ridge waveguides. image
We analyse the behaviour of single photon states within rectangular waveguides. The fields were solved for using normal modes of rectangular waveguides. The system is taken to be coupled to a cavity-atom system and th...
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ISBN:
(纸本)9781510654761;9781510654754
We analyse the behaviour of single photon states within rectangular waveguides. The fields were solved for using normal modes of rectangular waveguides. The system is taken to be coupled to a cavity-atom system and the coupling between the cavity and waveguide was analysed to compute a coupling frequency. The single mode approximation was used assuming a Jaynes-Cummings form for the Hamiltonian to arrive at field operator expressions. These were used along with photodetection theory to compute the output detection probabilities for single photon states in the dominant mode. Finally, the single photon state was analysed within an MZI and a directional coupler. Y splitters and combiners were assumed to have 50% power division. Our results suggest that for single photon states, there is little to no deviation from the classical case in terms of input and output.
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