近地爆烟尘由不同粒径尺度的放射性颗粒组成，且运动的时空尺度大。针对近地爆烟尘的大气γ电离辐射环境模拟这一难题，首先开展了γ大气辐射机理分析，进行了无风条件设定，建立了烟尘γ辐射的理论模型，其次引入和提出了相应的数值差分与积分算法，最后给出了对1 000 kt内华达近地爆烟尘在大气中的放射性活度和辐射剂量率的模拟算例，完成了一定的辐射环境时空演变规律总结与结果对比，对比发现本模型在保证活度结果一致性的同时，能计算出大气辐射剂量率的理论最大值。

A good thermo-optic property of strontium dodeca-aluminum oxide (SrAl12O12, SRA) host material is very advantageous to the development of high-performance lasers by doping rare-earth ions for gain medium. In this work, we report on diode-end-pumped high-performance continuous-wave and passively Q-switched Nd:SRA lasers. For continuous-wave operation, a maximum output power of 6.45 W is achieved at 1049 nm with a slope efficiency of about 41.6%. Using a Y3Al5O12 (YAG) etalon, we have firstly achieved a 1066 nm laser with a maximum output power of 4.15 W and a slope efficiency of about 27%, to the best of our knowledge. For passively Q-switched operation, with Cr4+:YAG as a saturable absorber, a maximum average output power of 1.82 W was achieved with the shortest pulse width of 18.2 ns at pulse repetition rate of 22.9 kHz. The single-pulse energy and pulse peak power were 79.4 μJ and 4.3 kW. This work has further verified that the Nd:SRA crystal is very promising for high-performance laser generation.

In this Letter, we have shown that a giant Goos–H nchen shift of a light beam reflected at terahertz frequencies can be achieved by using a composite structure, where monolayer graphene is coated on one-dimensional photonic crystals separated by a dielectric slab. This giant Goos–H nchen shift originates from the enhancement of the electrical field, owing to the excitation of optical Tamm states at the interface between the graphene and one-dimensional photonic crystal. It is shown that the Goos–H nchen shift in this structure can be significantly enlarged negatively and can be switched from negative to positive due to the tunability of graphene’s conductivity. Moreover, the Goos–H nchen shift of the proposed structure is sensitive to the relaxation time of graphene and the thickness of the top layer, making this structure a good candidate for a dynamic tunable optical shift device in the terahertz regime.

In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal (1DPC) separated by a dielectric. Due to the excitation of optical Tamm states (OTSs) at the interface between the graphene and 1DPC, a strong absorption phenomenon occurs induced by the coupling of the incident light and OTSs. Although the perfect absorption produced by a metal–distributed Bragg reflector structure has been researched extensively, it is generally at a fixed frequency and not tunable. Here, we show that the perfect absorption at terahertz frequency not only can be tuned to different frequencies but also exhibits a high absorption over a wide angle range. In addition, the absorption of the proposed structure is insensitive to the polarization, and multichannel absorption can be realized by controlling the thickness of the top layer.

The photonic spin Hall effect (SHE) has been intensively studied and widely applied, especially in spin photonics. However, the SHE is weak and is difficult to detect directly. In this paper, we propose a method to enhance SHE with the guided-wave surface-plasmon resonance (SPR). By covering a dielectric with high refractive index on the surface of silver film, the photonic SHE can be greatly enhanced, and a giant transverse shift of horizontal polarization state is observed due to the evanescent field enhancement near the interface at the top dielectric layer and air. The maximum transverse shift of the horizontal polarization state with 11.5 μm is obtained when the thickness of Si film is optimum. There is at least an order of magnitude enhancement in contrast with the transverse shift in the conventional SPR configuration. Our research is important for providing an effective way to improve the photonic SHE and may offer the opportunity to characterize the parameters of the dielectric layer with the help of weak measurements and development of sensors based on the photonic SHE.