Spectral Characteristics Analysis of a Novel Optical Comb Filter Based on a Single-Core 2D Chirped Optical Fiber Grating

Resonator structures with a multiwavelength filter are critical devices for the fabrication of stable output multiwavelength fiber lasers. In this study, we propose a spatially separated multiwavelength filter based on a 2D chirped fiber grating. The resonant fields of lasers with different wavelengths are spatially separated, reducing cross-gain modulation. In addition, the structure of the 2D chirped fiber grating is analyzed, and the spectral output characteristics of the device are investigated for different grating parameters, which provides theoretical guidance for designing such a novel optical comb filter. Furthermore, by fabricating the 2D chirped fiber grating onto a single-mode fiber, a multiwavelength filter with 17 wavelengths, a frequency interval of approximately 88 GHz, and a grating length of 4.8 cm is created. This device is characterized by its compact structure and simple fabrication method.