提出一种新的多级联线性啁啾光纤光栅密集梳状滤波器,该结构由多个相同的线性啁啾光纤光栅(LCFBG)组成,并对其光谱特性进行了模拟和分析。研究表明,滤波通道间隔由单元光栅构成的法布里-珀罗(F-P)谐振腔的长度确定,通过选择合适的光栅总啁啾量、光栅折射率调制深度和光栅级联数,可以获得反射率高、响应谱宽的多通道滤波效果。采用多级联方式,在较小折射率调制深度的情况下,可以实现高反射率,降低了通常对光栅折射率调制深度的要求。该结构由相同的线性啁啾光纤光栅级联而成,可以采用同一个光栅模板制作,容易实现。

A novel optical dense comb filter is proposed,which is composed of many identical linearly chirped fiber Bragg gratings (LCFBG).The spectral characteristics of optical dense comb filter are numerically simulated and analyzed. The results show that the channel spacing of filter is controlled by the length of Fabry-Perot (F-P) cavity which is equal to that of unit grating. By choosing optimal structure parameters of grating,for example,the total chirp,the index modulation depth of unit grating and the concatenated grating number,the reflection spectrum of the filter shows the characteristics of high reflectivity,large bandwidth and multi-channels. For the multi-concatenated gratings,which are easy to be made with a single grating mask,the high reflection of filter can be achieved with a low index modulation depth.