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Due to the extraordinary chemical and physical properties, ternary chalcogenides with wide‐range bandgap, unique structures, and exceptional photoelectric properties have attracted great interest recently. Among them, Chromium thiophosphate (CrPS4) is a promising semiconductor with excellent optical, mechanical, and electronic properties and has a lower lattice symmetry resulting in significant in‐plane anisotropy. Here, the polarization‐dependent nonlinear optical (NLO) responses of CrPS4 flake are investigated. Based on polarization‐resolved Raman spectroscopy, which identifies the crystal axis of sample, the anisotropic linear absorption spectra, I‐scan technique, and pump‐probe measurements are utilized to investigate the optical absorption information of CrPS4. The polarization‐dependent NLO responses are found originating from the anisotropic optical transition probability. And the polar optical phonons play an important role in carrier relaxation processes. Furthermore, CrPS4‐based all‐optical switches are proposed, which can modulate the transmittance of signal light (CW laser) by changing the polarization of switch light (fs laser). This work provides insights into polarization‐dependent CrPS4‐based devices, which is important to promote the potential applications in optical modulator, versatile optoelectronic detection, and so on. [ABSTRACT FROM AUTHOR]

Optical logic gates based on nonlinear optical property of material with ultrafast response speed and excellent computational processing power can break the performance bottleneck of electronic transistors. As one of the layered 2D materials, Ta2NiS5 exhibits high anisotropic mobility, exotic electrical response, and intriguing optical properties. Due to the low-symmetrical crystal structures, it possesses in-plane anisotropic physical properties. The optical absorption information of Ta2NiS5 is investigated by anisotropic linear absorption spectra, femtosecond laser intensity scanning (I-scan), and non-degenerate pump-probe technology. The I-scan results show a distinct maximum of ∼4.9 % saturable absorption (SA) and ∼4 % reverse saturable absorption (RSA) at different polarization directions of the incident laser. And, these unique nonlinear optical (NLO) properties originate from the anisotropic optical transition probability. Furthermore, the novel Ta2NiS5-based all-optical logic gates are proposed by manipulating the NLO absorption processes. And, the all-optical OR and NOR logic gates possess an ultrafast response speed approaching 1.7 THz. Meanwhile, an all-optical information transmission method with higher security and accuracy is achieved, which has promising potential to avoid the disclosure of information. This work provides a new path for designing versatile and novel optical applications based on Ta2NiS5 materials. [ABSTRACT FROM AUTHOR]

The on‐chip near‐infrared (NIR) lasing devices based on van der Waals (vdW) layered materials are highly desired owing to their widespread applications in optoelectronic communication, computing, and sensing. However, the single‐mode NIR lasing devices with superior performance based on vdW layered materials are hard to obtain because of complex and meticulous microcavity structure and the damage to layered materials during preparation. Here, a high‐quality NIR single‐mode lasing device in γ‐phase indium selenide (γ‐InSe) is achieved by using a transferrable planar microcavity. The single‐mode lasing devices based on distributed Bragg reflectors microcavity and super Tamm structure can be simply prepared with quality factors up to 5710 and 3526, respectively. And angle‐resolved spectra show that the lasing device has high directionality with divergence angle <5°. Moreover, the wavelength of lasing device can be tuned ≈30 nm by varying the cavity length via thickness control of γ‐InSe layer. These results not only suggest that γ‐InSe is a promising material for NIR lasing devices, but also present a simple and effective approach for preparing high‐quality lasing devices utilizing other vdW layered materials. [ABSTRACT FROM AUTHOR]

The layer-by-layer buildup of a two-dimensional transition metal dichalcogenide monolayer to form a stack is an important development for these materials, which performs many remarkable properties in the light–matter interaction. Herein, we find clear evidence of exciton–polaritons emerging from WS2/hBN/WS2 heterostructures embedded in a dielectric microcavity under optical pumping. A large Rabi splitting of 15 meV is observed at room temperature, which increases to 25 meV at 5 K. An all-dielectric Fabry–Pérot microcavity provides a simple but effective way to study the room temperature strong coupling between cavity photons and excitons. Our results pave the way for room-temperature polaritonic devices based on quantum-well van der Waals heterostructures. [ABSTRACT FROM AUTHOR]

Inorganic perovskites have become a widely investigated candidate for fabrication of high‐performance micro‐devices due to their excellent optoelectronic properties and stability to the environment. Especially, their excellent lasing characteristics as a micro/nanolaser source, combined with flexible substrates, have great potential in the field of wearable or foldable photonic device applications. Here, the high‐quality CsPbBr3 perovskite microsheets with stress‐induced grooves are directly prepared on the ultrathin fluorine mica by the chemical vapor deposition method, and the single‐mode lasers are realized in these large‐size (>15 × 15 µm) microsheets. Thanks to the flexibility of mica, bending induced tensile strain on CsPbBr3 microsheet causes the laser mode blueshift continuously and reversibly with 15.3 meV %−1, this can be well explained by the Lorentz oscillator model under lasing conditions. Furthermore, by using the first‐principles calculation, it is clarified that the bandedge blueshift originates from the distortion of {PbBr6}4− octahedra and the consequential increase of the bond length of Pb‐Br3 and the Pb‐Br3‐Pb bond angle. This work opens up a new way to realize on‐chip single‐mode lasers with microstructures, and is helpful for the application of flexible photonic device in the fields of integrated on‐chip sensors. [ABSTRACT FROM AUTHOR]