C-band 41-wavelength-switchable single-longitudinal-mode fiber laser with sub-kHz linewidth and high stability using a wide-band chirped Moiré fiber Bragg grating

A high-performance wavelength-switchable single-longitudinal-mode (SLM) fiber laser with ultra-narrow linewidth and high stability in C-band was proposed and demonstrated, mainly benefiting from the use of a wide-band chirped Moiré fiber Bragg grating (WB-CM-FBG) with 41 ultra-narrow channels. By combining the WB-CM-FBG with a manual tunable bandpass filter and using a subring cavity with a length of only 34 cm to efficiently stabilize the SLM lasing, we achieved switchable lasing operation among 41 wavelengths, with a switching-step of ~0.96 nm from 1526.592 nm to 1565.126 nm, covering the whole C-band, and obtained sub-kHz linewidth at every lasing wavelength. The high stability was validated by the measured slight fluctuations of lasing wavelength and optical power of <0.004 nm and <0.113 dB, respectively, in 1.5 h. To the best of authors’ knowledge, this is the state-of-the-art CM-FBG-based fiber laser reported with the greatest number of switchable-wavelengths covering C-band, and, what’s more, each switchable lasing wavelength was with sub-kHz linewidth. The performance of the proposed fiber laser can be improved further with good temperature compensation and vibration isolation packaging for practical applications.