On-chip structured light, with potentially infinite complexity, has emerged as a linchpin in the realm of integrated photonics. However, the realization of arbitrarily tailoring a multitude of light field dimensions in complex media remains a challenge1, Through associating physical light fields and mathematical function spaces by introducing a mapping operator, we proposed a data-driven inverse design method to precisely manipulate between any two structured light fields in the on-chip high-dimensional Hilbert space. To illustrate, light field conversion in on-chip topological photonics was achieved. High-performance topological coupling devices with minimal insertion loss and customizable topological routing devices were designed and realized. Our method provides a new paradigm to enable precise manipulation over the on-chip vectorial structured light and paves the way for the realization of complex photonic functions.

In the development of silicon photonics, the continued downsizing of photonic integrated circuits will further increase the integration density, which augments the functionality of photonic chips. Compared with the traditional design method, inverse design presents a novel approach for achieving compact photonic devices. However, achieving compact, reconfigurable photonic devices with the inverse design that employs the traditional modulation method exemplified by the thermo-optic effect poses a significant challenge due to the weak modulation capability. Low-loss phase change materials (PCMs) exemplified by Sb2Se3 are a promising candidate for solving this problem benefiting from their high refractive index contrast. In this work, we first developed a robust inverse design method to realize reconfigurable silicon and phase-change materials hybrid photonic devices including mode converter and optical switch. The mode converter exhibits a broadband operation of >100 nm. The optical switch shows an extinction ratio of >25 dB and a multilevel switching of 41 (>5 bits) by simply changing the crystallinity of Sb2Se3. Here, we experimentally demonstrated a Sb2Se3/Si hybrid integrated optical switch for the first time, wherein routing can be switched by the phase transition of the whole Sb2Se3. Our work provides an effective solution for the design of photonic devices that is insensitive to fabrication errors, thereby paving the way for high integration density in future photonic chips.

Mid-infrared (mid-IR) on-chip photonic devices have attracted increasing attention because of their potential applications in chemical and biological sensing and optical communications. In particular, chalcogenide glasses (ChGs) have long been regarded as promising materials for mid-IR integrated photonics, owing to their broad infrared transparency, high nonlinearity, and excellent processing capabilities. Here, an inverse design approach is introduced to ChG photonic device design with a new robust inverse design method. A high-performance mid-IR inverse design polarization beam splitter, waveguide polarizer, mode converter, and wavelength demultiplexer are demonstrated for the first time. They all have a footprint of only several micrometers. The robust inverse design method could improve the robustness of device performance against fabrication variations and would be a general approach for designing and optimizing miniaturized chalcogenide photonic devices.

System-in-Package (SiP) has been facing the problem of excessive radiation leakage. In this article, a novel technique of absorptive sheet is proposed for suppressing unwanted microwave radiated emission in an advanced high-speed SiP module backed with a heat sink. Different from the conventional periodic resonant structure or absorptive film, the electromagnetic energy is consumed based on the mechanism of spoof surface plasmon polaritons (SSPP) in our design. By adjusting the length of the metallic strip to control its k-dispersion characteristics, the SSPP modes could be excited around one frequency point. Therefore, a relatively wide absorption band is created by arranging stepped strips in arrays on a dielectric medium. According to the electromagnetic distribution in the SiP module, SSPP-based absorptive units are circularly arranged to constitute the complete proposed absorptive sheet with adequate absorption efficiency. From the simulated results, the proposed design can provide 90$\%$ absorption performance covering a wide frequency range of 26.3–31.6 GHz, with a substrate thickness of only $\lambda _{L}$/228 and a total thickness of $\lambda _{L}$/134, where $\lambda _{L}$ is the wavelength at the lowest operating frequency. Finally, the proposed absorptive sheet is fabricated and measured, where measurement results agree well with the simulated ones, which corroborates the feasibility and effectiveness of applying the SSPP-based absorbing techniques for suppressing the radiated emission in microwave and millimeter-wave frequency range in SiP modules.

This article introduces the inverse design into the all-optical logic gates. Using direct-binary search (DBS) and the adjoint method, the ultra-small XOR logic gate is designed, and the size is only 1.2um*2.5um, which is the smallest record known so far. The device with parallel logic function in C-band and O-band is realized for the first time. All designs conform to standard processes, laying the foundation for the development of optical computing and optical neural networks.

This paper presents a topology optimization design method to achieve the inverse design for nanophotonics device. In this paper, we use the direct binary search algorithm (DBS) for inverse design and propose a 90° curved waveguide with an ultra-small bending radius (inner radius, r < 0.1λ0). The transmission rate exceeds 90% in 1380~1465nm, which nearly 10% higher than the traditional design. Furthermore, we design a compact all-optical XOR logic gate in the same method. All designs are compatible with the standard process, which laid the foundation for the development of optical computing and optical neural networks.

Optical logic operations lie at the heart of optical computing, and they enable many applications such as ultrahigh-speed information processing. However, the reported optical logic gates rely heavily on the precise control of input light signals, including their phase difference, polarization, and intensity and the size of the incident beams. Due to the complexity and difficulty in these precise controls, the two output optical logic states may suffer from an inherent instability and a low contrast ratio of intensity. Moreover, the miniaturization of optical logic gates becomes difficult if the extra bulky apparatus for these controls is considered. As such, it is desirable to get rid of these complicated controls and to achieve full logic functionality in a compact photonic system. Such a goal remains challenging. Here, we introduce a simple yet universal design strategy, capable of using plane waves as the incident signal, to perform optical logic operations via a diffractive neural network. Physically, the incident plane wave is first spatially encoded by a specific logic operation at the input layer and further decoded through the hidden layers, namely, a compound Huygens’ metasurface. That is, the judiciously designed metasurface scatters the encoded light into one of two small designated areas at the output layer, which provides the information of output logic states. Importantly, after training of the diffractive neural network, all seven basic types of optical logic operations can be realized by the same metasurface. As a conceptual illustration, three logic operations (NOT, OR, and AND) are experimentally demonstrated at microwave frequencies.

We systematically investigated graphene-based slot and multi-slot waveguides. A tri-slot waveguide which significantly enhances the light-graphene interaction was experimentally demonstrated with low insertion loss. By integrating a dual-layer graphene h-BN heterostructure on the tri-slot waveguide, a high efficiency modulator is designed, which combines the advantages of high modulation efficiency (0.376 dB/μm), low insertion loss (0.01 dB/μm), large modulation bandwidth (∼0.13 THz) and low power consumption (∼0.128 pJ/bit). Our work may promote the development of future high efficient graphene-based optical devices.

Electromagnetically induced transparency like effect, which can form a sharp transmission window within a broad spectrum, has been widely studied due to its potential in many optical devices. In this work, unlike traditional couple-ring resonator structure, we propose a new scheme to achieve electromagnetically induced transparency using only one hole-ring resonator. Thus, the proposed scheme can greatly miniaturize the device. At the wavelength of about 1550 nm, the structure can form multiple transparency windows and can behave as a refractive index sensor with high resolution, the figure of merit can reach larger than 530. The proposed scheme can pave the way for many practical applications such as optical sensors, optical switches and slow light devices.

In this work, a wide band slow light is achieved in a simple one-dimensional grating waveguide. A flat band indicating slow light with group index of 13 and bandwidth over 10nm is obtained.