(英)浸入式光栅谱线特性研究
投稿时间:2017-04-28  修订日期:2017-06-12  点此下载全文
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作者单位E-mail
唐茜 西安电子科技大学 qtang@xidian.edu.cn 
郭立新 西安电子科技大学 lxguo@xidian.edu.cn 
基金项目:国家自然科学基金青年基金(批准号:61501361)、国家重点实验室开放基金(批准号:SKLST201509)、教育部/广东省重点实验室开放基金(批准号:GD201712)、中科院重点实验室开放基金(批准号:LSIT201506)和中央高校科研业务费基金(批准号:JB160509)
中文摘要:浸入式光栅通常应用于光学材料折射率较高的红外谱段。因其特殊的工作模式,不可避免的存在一系列普通(工作在空气中)的反射式光栅不需要面临的问题,如介质内部特性导致的谱线条纹变化等情况,而它们对于浸入式光栅的应用却是十分重要的。论文推导了普通光栅长波端与短波端谱线长度的关系。针对折射率与波长相关的特点,以短波红外(1.5μm -2.5μm)为例,分析浸入式光栅的谱线位置分布及光谱分辨率变化特性。结果表明,当采用浸入式光栅时,谱线相较于普通光栅的分布有明显差异,“梯形”谱线会发生倾斜。短波红外谱段(1.5μm -2.5μm),由于介质折射率变化较大,“梯形”谱线倾斜程度较明显。在以长波(2.5μm,108级)配准Littrow条件时,谱线向短波端倾斜,以短波(1.5μm,180级)配准时,谱线向长波端倾斜,并且Littrow波长均漂离中心波长。在热红外谱段,由于折射率变化较小,“梯形”谱线倾斜较小,更接近普通光栅的情况。由于折射率的变化,浸入式光栅的光谱分辨率也随之发生改变。同一级中,波长增大,光谱分辨率增大;各级之间,级数减小(即波长增大),光谱分辨率减小。同时,由于高级次(短波) 光谱分辨率大于低级次(长波),因此各级谱线长度之比不再满足普通光栅中L_long/L_short =〖[λ_long/λ_short ]〗^2的关系。同时,论文结合分析结果对浸入式光栅的设计与探测器选择进行了讨论
中文关键词:光栅,浸入式,折射率,谱线漂移
 
Characteristics of the spectral lines of immersion gratings
Abstract:Immersion gratings are typically used in the infrared spectral band of optical materials with high refractive index. Issues that normal (operating in the air) reflection gratings do not usually face, such as changes in spectral line fringes resulting from the internal characteristics of the medium, inevitably arise due to its special operating mode. However, such problems are critical to the application of immersion gratings. This study investigates the relations between the lengths of the long- and short-wave ends of normal gratings. For the features of the relevance of the refractive index with wavelength, the short-wave infrared spectral band (1.5 μm–2.5 μm) is taken as an example to analyze the change characteristics of spectral line location and spectral resolution of immersion gratings. Results show that when immersion gratings are adopted, significant differences are observed in the distribution of spectral lines as compared with normal gratings, and “trapezoidal” spectral lines tilt. For short-wave infrared spectral lines (1.5 μm–2.5 μm), the inclination of the “trapezoidal” spectral lines becomes more apparent due to larger changes in the refractive index of the medium. When Littrow conditions are registered with short-wave length (2.5 μm, the 108th order), the spectral line tilts toward the short-wave end. When registration is done with long wave (1.5 μm, the 108th order), the spectral line tilts toward the long-wave end, and the Littrow wave length drifts away from the central wavelength. At the thermal infrared spectral band, as smaller changes occur in the refractive index, the tilt of “trapezoidal” spectral lines is smaller and more similar to that of normal gratings. The spectral resolution of immersion gratings varies due to changes in the refractive index. At the same order, the wavelength increases, and spectral resolution increases; between various orders, the series decrease (that is, wavelength increases), and the spectral resolution decreases. Meanwhile, considering that the high-order (short wave) spectral resolution is larger than the low-order (long wave) spectral resolution, the ratio of the lengths of spectral lines at various orders no longer meets the relation of L_long/L_short =〖[λ_long/λ_short ]〗^2 in normal gratings.
keywords:grating, immersion, refractive index, spectral line drift
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