Research and Fabrication of the Chirped Moiré Fiber Bragg Grating With Tunable Channels Based on Temperature Control

This study presents the design and practical demonstration of a fiber comb filter featuring tunable channels based on the chirped Moiré fiber Bragg grating (CMFBG). This CMFBG is comprised of a Moiré fiber Bragg grating (MFBG) and a temperature control system. The number of channels is determined by the design parameters of this MFBG. Meanwhile, the channel spacing could be linearly regulated by precisely manipulating the linear temperature gradient at both ends of the CMFBG. The spectral characteristics of the CMFBGs with different parameters are investigated by numerical simulations, which provide theoretical guidance for designing such a fiber comb filter. Experimentally, a 5-channel comb filter is obtained, and its free spectral range (FSR) can be continuously tuned within the range of 0.096 nm to 0.184 nm. Furthermore, a comparative analysis of the CMFBGs with varying lengths and configurations is carried out. The proposed tunable comb filter has the potential to be used in wavelength-division-multiplexing systems, fiber lasers, and fiber optic sensors.