No abstract

We present and realized a novel structure of ultra-longperiod fiber gratings (ULPG), which can inhibit specific resonance peak selectively while the wavelength of other peaks rarely change. This compounded ULPG is similar in form to two uniform ULPG interlaced through parallel moving. Owing to the ratio moved equivalent, the peaks caused by 2nd, 3rd or 4th diffraction order will be intentionally inhibited. Experimental results has verified this novel structure and the transmission spectrum observed in experiment shows accordance with the theoretical analysis.