Ultra-Compact Power Splitters with Low Loss in Arbitrary Direction Based on Inverse Design Method

The power splitter is a device that splits the energy from an input signal into multiple outputs with equal or uneven energy. Recently, the use of algorithms to intelligently design silicon-based photonic devices has attracted widespread attention. Thus, many optimization algorithms, which are called inverse design algorithms, have been proposed. In this paper, we use the Direct Binary Search (DBS) algorithm designed with three 1 × 3 power splitters with arbitrary directions theoretically. They have any direction and can be connected to other devices in any direction, which greatly reduces the space occupied by the optical integrated circuit. Through the simulation that comes about, we are able to get the insertion loss (IL) of the device we designed to be less than 5.55 dB, 5.49 dB, and 5.32 dB, separately. Then, the wavelength is 1530–1560 nm, so it can be used in the optical communication system. To discuss the impact of the footprint on device performance, we also designed another device with the same function as the second one from the above three devices. Its IL is less than 5.40 dB. Although it occupies a larger area, it has an advantage in IL. Through the design results, three 1 × 3 power splitters can be freely combined to realize any direction, multi-channel, ultra-compact power splitters, and can be better connected with different devices to achieve different functions. At the same time, we also show an example of a combination. The IL of each port of the combined 1 × 6 power splitter is less than 8.82 dB.

All-optical binary computation based on inverse design method

The development of information technology urgently requires ultrafast, ultra-low energy consumption and ultra-high-capacity data computing abilities. Traditional computing method of electronic chips is limited by the bottleneck of Moore’s Law. All-optical computing of photonic chips provides a promising way to realize such high-performance data computing abilities. Until now, it is still a huge challenge to realize all-optical four arithmetic operations at the same time on a photonic chip. Here, we propose a new encoding scheme for all-optical binary computation, including n-bit addition, subtraction, multiplication and division. We theoretically present n-bit calculation and experimentally demonstrate 1 bit calculation. The computation part includes a half binary adder and a shifter, whose feature sizes are only 2 μm × 19.5 μm and 4 μm × 9 μm, respectively. The half binary adder and shifter consist of three low-loss basic devices through inverse design method. The distance between two adjacent basic devices is smaller than 1.5 μm, within wavelength magnitude scale. The response time is the propagation time of the signal light in a single device, within 100 fs. The threshold energy consumption is within 10 fJ/bit. Our results provide a new method to realize ultrafast, ultra-low energy consumption and ultra-high-capacity data processing abilities all-optical n-bit binary computing.

Study on realizing the personalized customization of bra cup by solving the inverse problem of bra cup design

In the process of bra cup customization, the matching between bra cup surface and breast shape largely depends on the practical experience of designers. To achieve effective customization, this study proposes an inverse design method. This method prescribes the surface of the main test section and subsequently optimizes the corresponding shape of the bra cup, thus minimizing the supremum of pressure in the target region. The optimization framework is mainly based on the particle swarm optimization algorithm and Kriging surrogate model. The inner surface of the bra cup represents the study model, and the three-dimensional morphology of the bra cup is characterized by the free-form deformation. The result exhibits a reduction of 22.51% in the pressure of the design cup as compared to the body size cup. The developed method can contribute to the engineering and personalized customization of the bra cup, thus further improving the fitting of the bra cup.

Inverse-designed ultra-compact high efficiency and low crosstalk optical interconnect based on waveguide crossing and wavelength demultiplexer

In this paper, we use the inverse design method to design an optical interconnection system composed of wavelength demultiplexer and the same direction waveguide crossing on silicon-on-insulator (SOI) platform. A 2.4 μm × 3.6 μm wavelength demultiplexer with an input wavelength of 1.3–1.6 μm is designed. When the target wavelength of the device is 1.4 μm, the insertion loss of the output port is − 0.93 dB, and there is − 18.4 dB crosstalk, in TE0 mode. The insertion loss of the target wavelength of 1.6 μm in TE0 mode is − 0.88 dB, and the crosstalk is − 19.1 dB. Then, we designed a same direction waveguide crossing, the footprint is only 2.4 μm × 3.6 μm, the insertion loss of the wavelength 1.4 μm and 1.6 μm in TE0 mode is − 0.99 dB and − 1 dB, and the crosstalk is − 12.14 dB and − 14.34 dB, respectively. Finally, an optical interconnect structure composed of two devices is used, which can become the most basic component of the optical interconnect network. In TE0 mode, the insertion loss of the output wavelength of 1.4 μm at the output port is − 1.3 dB, and the crosstalk is − 29.36 dB. The insertion loss of the output wavelength of 1.6 μm is − 1.39 dB, and the crosstalk is − 38.99 dB.

Aerodynamic Inverse Design of Transonic Compressor Cascades with Stabilizing Elastic Surface Algorithm

The upgraded elastic surface algorithm (UESA) is a physical inverse design method that was recently developed for a compressor cascade with double-circular-arc blades. In this method, the blade walls are modeled as elastic Timoshenko beams that smoothly deform because of the difference between the target and current pressure distributions. Nevertheless, the UESA is completely unstable for a compressor cascade with an intense normal shock, which causes a divergence due to the high pressure difference near the shock and the displacement of shock during the geometry corrections. In this study, the UESA was stabilized for the inverse design of a compressor cascade with normal shock, with no geometrical filtration. In the new version of this method, a distribution for the elastic modulus along the Timoshenko beam was chosen to increase its stiffness near the normal shock and to control the high deformations and oscillations in this region. Furthermore, to prevent surface oscillations, nodes need to be constrained to move perpendicularly to the chord line. With these modifications, the instability and oscillation were removed through the shape modification process. Two design cases were examined to evaluate the method for a transonic cascade with normal shock. The method was also capable of finding a physical pressure distribution that was nearest to the target one.

An inverse design method for determining the optimal tributary flow into main stream in a rainstorm period

To ensure water quality at the control cross-section of main stream (CCMS) in a rainstorm period, an inverse design method was proposed to determine the optimal discharge flow of tributary rivers. The design variables are tributary discharges and the target variables are the required concentrations of chemical oxygen demand (COD), dissolved oxygen (DO) and ammonia nitrogen (NH3-N) at CCMS. The relationship between target variables and design variables was identified using artificial neural network (ANN). The database was obtained by Environmental Fluid Dynamics Code (EFDC) and the optimal tributary discharges were obtained by genetic algorithm (GA) coupled with well-trained ANN. The results showed the following results: (a) The relative prediction errors of ANN are mostly less than 5%. (b) When the inlet flow rate is 0 m3/s, 30 m3/s, 50 m3/s, 100 m3/s and 200 m3/s, the optimization total discharges of tributaries are 5.7 m3/s, 12.5 m3/s, 18.6 m3/s, 33.4 m3/s and 61.8 m3/s, respectively. (c) Most of optimization plans satisfy entirely the water quality requirements at CCMS except a few plans, which the relative errors between optimized results and required values of COD and DO are less than 0.4% and 0.1%, respectively. The study showed that the inverse design method is efficient for determining the optimal discharges of multiple tributaries.