The 2D layered materials are promising candidates for broadband, low‐cost photodetectors. One deficiency of 2D materials is the relatively low absorbance of light, limiting the applications of the 2D photodetectors. Doping of plasmonic nanoparticles into 2D materials may enhance the optical absorbance owing to the localized surface plasmonic resonance (LSPR) effect; however, considerable defects may be introduced into the 2D materials at the same time, resulting in certain degradation of device performance. Here, a novel design of 2D photodetectors with enhanced photoresponsivity by non‐contact plasmonic nanoparticles (NPs) is proposed, consisting of a hybrid structure of few‐layer SnSe2 transferred a fused silica (SiO2) plate with embedded Ag NPs. The system of Ag NPs‐in‐SiO2 shows strong LSPR effect with significantly enhanced optical absorption, acting on SnSe2 in a non‐contact configuration. Benefiting from well‐preserved intrinsic features of SnSe2 and LSPR effect, the responsivity of the photodetector is enhanced by 881 times with the bias voltage of 0.1 V, which is superior to previously reported results of plasmon‐enhanced 2D photodetectors. Moreover, the SiO2 with embedded Ag NPs is recyclable and can be easy to be recombined with different 2D materials. This work offers additional strategy for development of efficient, low‐cost 2D photodetectors by using plasmonic NPs.

Thin‐film lithium niobate platform, namely lithium‐niobate‐on‐insulator (LNOI), brings new opportunities for integrated photonics, taking advantages from both outstanding crystalline properties and special structural features. The excellent properties of LNOI have triggered development of a variety of on‐chip photonic devices for light generation and manipulation. However, as an indispensable component for photonic circuit with full functionalities, the thin‐film photodetector lacks in portfolios of LNOI‐based devices due to standing obstacles of low electrical conductivity and poor photoelectric conversion ability. Here, a self‐powered broadband LNOI photodetector based on enhanced photovoltaic effect, benefitting from encapsulated plasmonic nanoparticles and doped silver ions, is reported. Maximum responsivity of 0.25 A W−1 and detectivity (1.56 × 1014 Jones) are achieved. First‐principle calculations and electric‐field simulation reveal intrinsic mechanisms and crucial roles of plasmonic nanoparticles and silver ions on photocurrent generation and collection. This work opens an avenue to develop high‐performance on‐chip LNOI photodetectors, offering a conceivable means toward multiple‐functional photonic circuits.

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In this Letter, we report a tailored 532/1064-nm demultiplexer based on a multimode interference (MMI) coupler with an efficiency of 100%. The device structure is designed according to the self-imaging principle, and the propagation and the wavelength division performance are simulated by the beam propagation method. The demultiplexer is fabricated in a y-cut LiNbO3 crystal by femtosecond laser direct writing (FLDW) combined with the ion implantation technique. The end-face coupling system is used to measure the near field intensity distribution, and the spectra collected from the output ports are obtained by spectrometers. The simulated and the experimental results indicate that the customized demultiplexer in the LiNbO3 crystal presents excellent wavelength division performance operating at 532 nm and 1064 nm. This work demonstrates the application potential of FLDW technology for developing miniaturized photonic components and provides a new strategy for fabricating high-efficiency integrated wavelength division devices on an optical monocrystalline platform.