Hao Junbo, Ma Ting, Ye Zilin, Chen Chen, Yang Dahai, Zhou Keya, Wang Yiqun, Jin Peng, Lin Jie
Key Laboratory of Micro-systems and Micro-structures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
Nanotechnology. 2022 Mar 8;33(22). doi: 10.1088/1361-6528/ac547b.
Long-wave infrared imaging systems are widely used in the field of environmental monitoring and imaging guidance. As the core components, the long-wave infrared lenses suffer the conditions of less available materials, difficult processing, large volume and mass. Metalens composed of sub-wavelength structures is one of the most potential candidates to achieve a lightweight and planar optical imaging systems. Meanwhile, it is essential to obtain large-aperture infrared lenses with high power and high resolution. However, it is difficult to use the finite-difference time-domain method to simulate a large-aperture metalens with the diameter of 201 mm due to the large amount of computational memory and computational time required. Here, to solve the mentioned problem, we firstly propose a simulation method for designing a large-aperture metalens, which combines the finite-difference time-domain algorithm and diffraction integration. The finite-difference time-domain algorithm is used to simulate the meta-atom's transmitted complex amplitude and the one-dimensional simplification of the diffraction integral is to calculate the focused field distributions of the designed metalens. Furthermore, the meta-atom spatial multiplexing is applied to design the all-silicon metalenses with the aperture of 201 mm to realize dual-wavelength (10 and 11m) achromatic focusing, super anomalous dispersion focusing and super normal dispersion focusing. The designed metalenses are numerically confirmed, which reveal the feasibility of all-silicon sub-wavelength structures to accomplish the multiwavelength dispersion control. The designed all-silicon metalenses have the advantage of lightweight and compact. The proposed method is effective for the development of large-aperture imaging systems in the long-wave infrared.
长波红外成像系统在环境监测和成像制导领域有着广泛应用。作为核心部件，长波红外镜头面临着可用材料少、加工困难、体积和质量大等问题。由亚波长结构组成的超构透镜是实现轻量化平面光学成像系统最具潜力的候选方案之一。同时，获得高功率、高分辨率的大口径红外镜头至关重要。然而，由于所需的计算内存和计算时间量大，很难用时域有限差分法模拟直径为201毫米的大口径超构透镜。在此，为解决上述问题，我们首先提出一种设计大口径超构透镜的模拟方法，该方法将时域有限差分算法和衍射积分相结合。时域有限差分算法用于模拟超原子的透射复振幅，衍射积分的一维简化用于计算所设计超构透镜的聚焦场分布。此外，应用超原子空间复用设计孔径为201毫米的全硅超构透镜，以实现双波长（10和11微米）消色差聚焦、超反常色散聚焦和超正常色散聚焦。所设计的超构透镜经数值验证，揭示了全硅亚波长结构实现多波长色散控制的可行性。所设计的全硅超构透镜具有轻量化和紧凑的优点。该方法对长波红外大口径成像系统的发展有效。
