We propose and numerically investigate a photonic crystal fiber (PCF) based on As₂S₃ for supporting the orbital angular momentum (OAM) modes up to 26. The designed PCF is composed of four well-ordered air hole rings in the cladding and an air hole at the center. The OAM modes can be well separated due to the large effective index difference of above 10^-4 between the eigenmodes and maintain single-mode condition radially. In addition, the dispersions of the modes increase slowly with wavelengths, while the confinement loss keeps as low as 10^-9 dB/m. The proposed PCF increases the supported OAM modes which could have some potential applications in short-distance, high-capacity transmission.

We report the coexistence of high-order harmonic soliton molecules and rectangular noise-like pulses (NLP) in a figure-eight fiber laser mode-locked by a nonlinear amplifying loop mirror. The harmonic soliton molecule has a repetition rate of 936.6 MHz, corresponding to the 466th harmonics of the fundamental cavity repetition rate, with soliton separation of 16.5 ps. Meanwhile, the rectangular NLP operates at the fundamental repetition rate. In addition, these two types of pulses could be generated independently by manipulating the polarization controllers. The experimental results demonstrate an interesting operation regime of the fiber laser and contribute to enriching the dynamics of mode-locked pulses in fiber lasers.

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The effect of temperature on optical performance of a dual‐layer liquid crystal display (LCD) is investigated by considering LC material parameter and structural deformation of LC panels simultaneously. First, the optical anisotropy of LC material under the influence of temperature is calculated theoretically. Then, the thermal deformations of the dual‐layer LC panels caused by temperature are simulated. Combined with the two factors, the change in optical performance of a dual‐layer LCD under the influence of temperature can be analyzed. In white state, the color in the central area of a dual‐layer LCD is shifted towards blue, and a yellowish border in the edge area may appear. In gray or black state, there may be a light leakage in the edge area of a dual‐layer LCD under the influence of temperature.

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