A novel method enabling the production of an ultrabroad dual-triangular filter (DTF) is proposed and numerically demonstrated, which is realized by using an optimized phase-modulated helical long-period fibre grating (PM-HLPG) operated especially at wavelengths near the dispersion-turning-point (DTP) of cladding-mode LP${}_{\mathrm{1,10}}$. As a typical design example, four linearly spectral regions, each with dynamic ranges of $\sim$177 nm in wavelength and $\sim$82% in transmission loss, have been successfully achieved, which are the best results reported to date among all grating-based triangular filters. It is believed that the proposed DTF will find potential applications in broadband power-interrogated fibre sensing systems.

提出了一种能够生产超宽双三角滤波器 (DTF) 的新方法并进行了数值演示，该方法是通过使用优化的相位调制螺旋长周期光纤光栅 (PM-HLPG) 实现的，该光栅尤其在色散附近的波长下工作- 包层模式 LP 的转折点 (DTP)${}_{\mathrm{1,10}}$. 作为一个典型的设计示例，四个线性光谱区域，每个区域的动态范围为$～$177 nm 波长和 $～$82% 的传输损耗已成功实现，这是迄今为止所有基于光栅的三角滤波器中报告的最佳结果。相信所提出的 DTF 将在宽带功率询问光纤传感系统中找到潜在的应用。