Miniaturized spectrometers have been widely researched in recent years, but few studies are conducted with on-chip multimode schemes for mode-division multiplexing (MDM) systems. Here we propose an ultracompact mode-division demultiplexing spectrometer that includes branched waveguide structures and graphene-based photodetectors, which realizes simultaneously spectral dispersing and light fields detecting. In the bandwidth of 1500–1600 nm, the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE1–TE4 by Tikhonov regularization optimization. Empowered by deep learning algorithms, the 15-nm resolution of parallel reconstruction for TE1–TE4 is achieved by a single-shot measurement. Moreover, by stacking the multimode response in TE1–TE4 to the single spectra, the 3-nm spectral resolution is realized. This design reveals an effective solution for on-chip MDM spectroscopy, and may find applications in multimode sensing, interconnecting and processing.Miniaturized spectrometers have been widely researched in recent years, but few studies are conducted with on-chip multimode schemes for mode-division multiplexing (MDM) systems. Here we propose an ultracompact mode-division demultiplexing spectrometer that includes branched waveguide structures and graphene-based photodetectors, which realizes simultaneously spectral dispersing and light fields detecting. In the bandwidth of 1500–1600 nm, the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE1–TE4 by Tikhonov regularization optimization. Empowered by deep learning algorithms, the 15-nm resolution of parallel reconstruction for TE1–TE4 is achieved by a single-shot measurement. Moreover, by stacking the multimode response in TE1–TE4 to the single spectra, the 3-nm spectral resolution is realized. This design reveals an effective solution for on-chip MDM spectroscopy, and may find applications in multimode sensing, interconnecting and processing.

The past two decades have seen a drastic progress in the development of semiconducting metal-halide perovskites (MHPs) from both the fundamentally scientific and technological points of view. The excellent optoelectronic properties and device performance make perovskites very attractive to the researchers in materials, physics, chemistry and so on. To fully explore the potential of perovskites in the applications, various techniques have been demonstrated to synthesize perovskites, modify their structures, and create patterns and devices. Among them, photo-processing has been revealed to be a facile and general technique to achieve these aims. In this review, we discuss the mechanisms of photo-processing of perovskites and summarize the recent progress in the photo-processing of perovskites for synthesis, patterning, ion exchange, phase transition, assembly, and ion migration and redistribution. The applications of photo-processed perovskites in photovoltaic devices, lasers, photodetectors, light-emitting diodes (LEDs), and optical data storage and encryption are also discussed. Finally, we provide an outlook on photo-processing of perovskites and propose the promising directions for future researches. This review is of significance to the researches and applications of perovskites and also to uncover new views on the light-matter interactions.The past two decades have seen a drastic progress in the development of semiconducting metal-halide perovskites (MHPs) from both the fundamentally scientific and technological points of view. The excellent optoelectronic properties and device performance make perovskites very attractive to the researchers in materials, physics, chemistry and so on. To fully explore the potential of perovskites in the applications, various techniques have been demonstrated to synthesize perovskites, modify their structures, and create patterns and devices. Among them, photo-processing has been revealed to be a facile and general technique to achieve these aims. In this review, we discuss the mechanisms of photo-processing of perovskites and summarize the recent progress in the photo-processing of perovskites for synthesis, patterning, ion exchange, phase transition, assembly, and ion migration and redistribution. The applications of photo-processed perovskites in photovoltaic devices, lasers, photodetectors, light-emitting diodes (LEDs), and optical data storage and encryption are also discussed. Finally, we provide an outlook on photo-processing of perovskites and propose the promising directions for future researches. This review is of significance to the researches and applications of perovskites and also to uncover new views on the light-matter interactions.