Author Affiliations
Abstract
1 School of Electronic Science and Engineering, University of Electronic Science and Technology of China (UESTC)https://ror.org/04qr3zq92, Chengdu 611731, China
2 State Key Laboratory of Terahertz and Millimeter Wave, City University of Hong Kong, Hong Kong 999077, China
3 Department of Electrical Engineering, City University of Hong Kong, Hong Kong 999077, China
Optical antennas have received considerable attention in recent years due to their unique ability to convert localized energy to freely propagating radiation and vice versa. Sidelobe level (SLL) is one of the most crucial parameters in antenna design. A low SLL is beneficial to minimize the antenna interference with other optical components. Here a plasmonic optical leaky-wave antenna with low SLL is reported. Shifting spatial frequency by periodically modulating the electric-field amplitude in a plasmonic gap waveguide enables a free-space coupled wave out of the antenna. At the same time, precise control of the aperture fields by the modulation depth allows for reducing SLL. Simulation results indicate that the proposed design can achieve a high directivity of 15.8 dB and a low SLL of at the wavelength of 1550 nm. A low SLL below is experimentally demonstrated within the wavelength range from 1527 to 1570 nm. In addition, the low-SLL property is further verified by comparing it with a uniformly modulated antenna. By modulating the guided waves in the plasmonic gap waveguide in different forms, the aperture fields can be flexibly arranged to achieve arbitrary wavefront shaping. It bridges the gap between guided and free-space waves and empowers plasmonic integrated devices to control free-space light, thus enabling various free-space functions.
Photonics Research
2023, 11(9): 1500
1 上海应用技术学院, 上海 201418
2 浙江亿米光电科技有限公司, 杭州 314100
针对LED高光效、低功耗的要求, 在分析LED光学性能的基础上, 采用了COB(chip on board)即板上芯片封装技术。研究了不同电流下和点亮不同时间后, 分析其LED光通量、光效和色温。研究分析影响LED光学性能的因素并进行测试。结果表明, 用两种色温接近3 000 K的样品, 电流由500 mA增大到900 mA, 色温升高了1.685%、2.626%, 光通量也随着电流的变大而升高68.532%、84.625%, 但相反光效却降低了13.535%、9.971%; 而在电流保持不变的情况下, 点亮的时间由0~1 min、0~5 min、0~10 min, 其色温分别上升了0.537%、1.209%、2.384%; 0.369%、1.104%、2.943%, 同时, 光通量分别降低1.474%、4.855%、7.493%; 2.073%、3.859%、7.793%, 光效也分别降低2.527%、4.617%、6.671%; 2.171%、4.903%、7.579%。实验发现, 电流与点亮时间直接影响LED光学性能。
光学性能 电流 时间 光谱能量分析 chip on board (COB) COB optical performance LED light-emitting diode (LED) electric current time spectral energy analysis
1 上海应用技术学院 理学院, 上海 201418
2 上海应用技术学院 材料与工程学院, 上海 201418
3 浙江亿米光电科技有限公司, 浙江 嘉兴 314100
4 上海博恩世通光电股份有限公司, 上海 201108
立体发光灯片的关键是在保证光通量的前提下,如何获得均匀的正反面发光.本文对3种荧光粉平面涂覆立体灯片的正面和反面的瞬态和稳态光通量、色温、色品坐标进行了研究,发现直接涂覆荧光粉胶的灯片总的光通量最大,但正反面的发光性能相差很大；在涂覆荧光粉之前先平面涂覆一层硅胶,可获得正反面发光较均匀的灯片；而在该硅胶层内掺杂扩散粉的灯片,不但没有提高灯片的正反面发光均匀度,反而大幅度降低了光通量值.此外,测试3种样品的发光角度,发现其发光角度分布相似,而发光强度与积分球测试的光通量比值相近.结果表明,涂覆荧光粉之前先平面涂覆一层硅胶工艺,既可以保证立体发光灯片具有较大的光通量又可以获得均匀的正反面发光.
立体发光 LED灯片 光通量 色温 色品坐标 three-dimensional light-emitting LED lamp luminous flux color temperature chromaticity coordinate
