Affiliation:
1. Shenzhen University
2. Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ)
Abstract
We propose and demonstrate the inscription of ultra-short distributed Bragg reflector fiber lasers (DBR-FLs) in Er/Yb co-doped fiber (EYDF) using a femtosecond laser plane-by-plane (Pl-b-Pl) method. By integrating the spherical aberration (SA) with a laser 2D scanning process, a planar refractive index modification (RIM) region can be induced in the fiber core. Thanks to the Pl-b-Pl inscription, a high-quality fiber Bragg grating (FBG) in an EYDF is produced, exhibiting a grating strength exceeding 40 dB and an insertion loss of 0.1 dB. Subsequently, an ultra-short DBR-FL with an entire length of 7.3 mm is fabricated by the Pl-b-Pl inscription. The Pl-b-Pl ultra-short DBR-FL exhibits an improved slope efficiency of 0.7% compared with the DBR-FLs fabricated using another two direct-writing techniques, namely line-by-line (LbL) and point-by-point (PbP) methods. Furthermore, this ultra-short DBR-FL generates single-frequency and single-polarization radiation with a narrow linewidth (9.4 kHz) and a low relative intensity noise (-105.8 dB/Hz). Moreover, a wavelength-division-multiplexed array consisting of eight ultra-short DBR-FLs with distinct lasing wavelengths is successfully created. The Pl-b-Pl ultra-short DBR-FLs with excellent output performances offer significant potential for high-sensitivity sensing applications requiring high spatial resolution.
Funder
National Natural Science Foundation of China
National Key Research and Development Program of China
Guangdong Provincial Department of Science and Technology
Shenzhen Key Laboratory of Ultra-fast Laser Micro/Nano Manufacturing