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A novel passively mode-locked all-fiber laser using a chiral fiber grating as a polarization-selective element is demonstrated for the first time, to the best of our knowledge. The chiral fiber grating serves as a key component to form an artificial saturable absorber to realize mode locking through nonlinear polarization rotation in the cavity. The laser generates stable short pulses with energy of 0.34 nJ, a fundamental repetition rate of 3.27 MHz, and an FWHM bandwidth of 28 nm. We also show that harmonic mode-locked pulse trains of different orders can be obtained by increasing the pump power.

Er‐activated fiber lasers are critical for many significant applications, including fiber communication, gas sensing, lidar and military. Although the design of suitable fiber materials has improved the performance of Er‐activated fiber lasers, extension of their operation wavebands still remains a significant challenge. Here, a compact all‐fiber laser is proposed and demonstrated, which can support lasing beyond 1630 nm, based on an Er‐activated hybridized glass fiber. The collaborative theoretical analysis and experimental characterization indicate that various distinct structure units can form in the hybridized fiber. This leads to the notable inhomogeneous spectral broadening. By using this hybridized fiber, a tunable fiber laser device is constructed and the wavelength can be rationally tuned in the range from 1609 to 1631 nm by mechanically stretching the fiber Bragg gratings (FBGs) manufactured by the point‐by‐point femtosecond laser inscription. Furthermore, a new fiber sensor system based on this seldom exploration waveband is built and efficient ethylene detection is demonstrated. The results highlight that rational hybridization mediated short‐ and medium‐structure modification strategy, demonstrated here in Er‐activated fiber laser, can be extended to other rare‐earth glass fiber systems for the exploration of fiber devices at new wavebands. [ABSTRACT FROM AUTHOR]

A compact self-Q-switched Nd-doped silica all-fiber laser near 920 nm is experimentally demonstrated for the first time. Under an 808 nm laser diode (LD) pumping, a pair of homemade cavity mirrors that include a fiber Bragg grating (FBG) and a fiber end-facet mirror (FM) construct a compact and simple all-fiber resonator. A piece of 2.8-m-long Nd-doped silica fiber not only provides an optical gain, but also functions as a saturable absorber (SA). Stable Q-switching operation was successfully achieved. The pulses of 919.8 nm are generated at a threshold of 90 mW, and the maximum average power obtained is 8.56 mW with a pulse width of 1.62 μ s and a repetition rate of 72.03 kHz. And especially, a single pulse energy of 123.4 nJ is realized. To the best of our knowledge, this work represents the first compact Q-switched Nd-doped silica all-fiber laser operating at 919.8 nm, and the highest pulse energy is highlighted in the pulsed Nd-doped all-fiber lasers. [ABSTRACT FROM AUTHOR]