A Four Green TM/Red TE Demultiplexer Based on Multi Slot-Waveguide Structures

A Compact Polarization MMI Combiner Using Silicon Slot-Waveguide Structures

The study of designing a compact transverse electric (TE)/transverse magnetic (TM) polarization multimode interference (MMI) combiner based on silicon slot-waveguide technology is proposed for solving the high demands for high-speed ability alongside more energy power and minimizing the environmental impact of power consumption, achieving a balance between high-speed performance and energy efficiency has become an important consideration in an optical communication system. The MMI coupler has a significant difference in light coupling (beat-length) for TM and TE at 1550 nm wavelength. By controlling the light propagation mechanism inside the MMI coupler, a lower order of mode can be obtained which can lead to a shorter device. The polarization combiner was solved using the full-vectorial beam propagation method (FV-BPM), and the main geometrical parameters were analyzed using Matlab codes. Results show that after a short light propagation of 16.15 μm, the device can function as TM or TE combiner polarization with an excellent extinction ratio of 10.94 dB for TE mode and 13.08 dB for TM mode with low insertion losses of 0.76 dB (TE) and 0.56 dB (TM) and the combiner function well over the C-band spectrum. The polarization combiner also has a robust MMI coupler length tolerance of 400 nm. These attributes make it a good candidate for using this proposed device in photonic integrated circuits for improving power ability at the transmitter system.

Low-loss and broadband cascaded SiN RGB coupler with dual-mode interference

We design and demonstrate a cascaded SiN-based RGB coupler with dual-mode interference (DMI) for a micro laser scanning image projector. The DMI configuration in SiN-based waveguides mitigates the adverse effects of self-image point deviation caused by wavelength dispersion, achieving decreased device length and high transmission efficiency. The underlying mechanisms are discussed based on coupled-mode theory and 3D finite difference time domain simulation. A small footprint of 3µm×70µm is achieved for the RGB coupler device without input/output circuits, and the insertion losses are less than 0.56 dB at RGB wavelengths. There are two orders of magnitude reduction in device length as compared with the conventional S i O ₂-based RGB coupler, which greatly promotes the miniaturization of the couplers and displays integration advantages with a laser diode and waveguide photodetector. In addition, the 3 dB bandwidth is over 50 nm for the coupler, and it demonstrates good fabrication tolerance. This design can further be integrated into visible light communication systems and applied to visible light integrated photonics.

GD (Generative Design) Applied to a Plastics Recovery Drone (PRD) Using IDeS (Industrial Design Structure)

The evolution of innovative and systematic design methodologies over time has widened the design concept involvement from the product development phase, which also includes the production and start-up phases. Literature findings have presented to accomplish a Generative Design (GD) approach through the application of an innovative method called Industrial Structure Design (IDeS), a systematic design method able to discover the customer’s needs and the fundamental technical solutions to obtain a good innovative product, involving the whole organization for this achievement. Nevertheless, there is a social demand for solutions to the dramatic and growing problem of marine pollution from plastic materials, encouraging the designers to conceive a new innovative drone for waste collection at sea. Therefore, this study aims to merge all the most advanced design technologies with IDeS in an integrated way, by generating a structure that can also be adopted to plan the organization of a production company. The approach is validated with the design of the Recovery Plastic Drone (RPD) obtained with the IDeS methodology, combining Design and Product development phases, leading to a better and innovative solution for the market.

Tunable Narrowband Silicon-Based Thermal Emitter with Excellent High-Temperature Stability Fabricated by Lithography-Free Methods

Thermal emitters with properties of wavelength-selective and narrowband have been highly sought after for a variety of potential applications due to their high energy efficiency in the mid-infrared spectral range. In this study, we theoretically and experimentally demonstrate the tunable narrowband thermal emitter based on fully planar Si-W-SiN/SiNO multilayer, which is realized by the excitation of Tamm plasmon polaritons between a W layer and a SiN/SiNO-distributed Bragg reflector. In conjunction with electromagnetic simulations by the FDTD method, the optimum structure design of the emitter is implemented by 2.5 periods of DBR structure, and the corresponding emitter exhibits the nearly perfect narrowband absorption performance at the resonance wavelength and suppressed absorption performance in long wave range. Additionally, the narrowband absorption peak is insensitive to polarization mode and has a considerable angular tolerance of incident light. Furthermore, the actual high-quality Si-W-SiN/SiNO emitters are fabricated through lithography-free methods including magnetron sputtering and PECVD technology. The experimental absorption spectra of optimized emitters are found to be in good agreement with the simulated absorption spectra, showing the tunable narrowband absorption with all peak values of over 95%. Remarkably, the fabricated Si-W-SiN/SiNO emitter presents excellent high-temperature stability for several heating/cooling cycles confirmed up to 1200 K in Ar ambient. This easy-to-fabricate and tunable narrowband refractory emitter paves the way for practical designs in various photonic and thermal applications, such as thermophotovoltaic and IR radiative heaters.

Enhancement of Luminance in Powder Electroluminescent Devices by Substrates of Smooth and Transparent Cellulose Nanofiber Films

Powder electroluminescent (EL) devices with an electric field type excitation are surface light sources that are expected to have a wide range of practical applications, owing to their high environmental resistance; however, their low luminance has hindered their use. A clarification of the relationship between the properties of the film substrates and the electroluminescence is important to drastically improve light extraction efficiency. In this study, powder EL devices with different substrates of various levels of surface roughness and different optical transmittances were fabricated to quantitatively evaluate the relationships between the substrate properties and the device characteristics. A decrease in the surface roughness of the substrate caused a clear increase in both the current density and the luminance. The luminance was found to have a direct relationship with the optical transmittance of the substrates. The powder EL device, which was based on a cellulose nanofiber film and was the smoothest and most transparent substrate investigated, showed the highest luminance (641 cd/cm2) when 300 V was applied at 1 kHz.

A Three Demultiplexer C-Band Using Angled Multimode Interference in GaN-SiO2 Slot Waveguide Structures

One of the most common techniques for increasing data bitrate using the telecommunication system is to use dense wavelength division multiplexing (DWDM). However, the implementation of DWDM with more channels requires additional waveguide coupler devices and greater energy consumption, which can limit the system performances. To solve these issues, we propose a new approach for designing the demultiplexer using angled multimode interference (AMMI) in gallium nitride (GaN)–silica (SiO₂) slot waveguide structures. SiO₂ and GaN materials are selected for confining the infrared light inside the GaN areas under the transverse electric (TE) field mode. The results show that, after 3.56 mm light propagation, three infrared wavelengths in the C-band can be demultiplexed using a single AMMI coupler with a power loss of 1.31 to 2.44 dB, large bandwidth of 12 to 13.69 nm, very low power back reflection of 47.64 to 48.76 dB, and crosstalk of −12.67 to −15.62 dB. Thus, the proposed design has the potential for improving performances in the telecommunication system that works with DWDM technology.

Ultra-Narrow-Band Filter Based on High Q Factor in Metallic Nanoslit Arrays

Here we propose a novel high Q ultra-narrow-band filter in the optical regime. Multiple high Q resonances are achieved in ultra-thin metallic nanoslit arrays on stacked low index–high index dielectric (LID–HID) substrate. Based on the cooperative effect of suppressed modes and transmission modes, the high spectral resolution of transmission peaks is obtained. The number and Q factor of transmission peaks can be freely manipulated by a simple combination of the stacked LID–HID. It is demonstrated that the linewidths of the transmission peaks can be reduced down to the extreme limit of 1 nm and the Q factor is up to 700 by optimizing the structure parameter of the three-layer LID–HID. The results provide a theoretical basis to design a multi-band nanophotonic device with a high Q factor and have potential applications in the next generation of high-resolution plasmonic biosensing and filtering.