Transient behaviors in a spectrum-tailored all-PM NALM mode-locked fiber laser.

We demonstrate an all-polarization-maintaining (PM) dispersion-managed mode-locked ytterbium-doped fiber oscillator based on a nonlinear amplifying loop mirror (NALM). Experimentally, three mode-locking regimes with distinct tailored spectra are achieved with carefully designed cavity setup and adjusted pump power. Using the dispersive Fourier transformation (DFT) technique, the real-time transition dynamics among these regimes are observed as the pump power decreases.

Spectral Failsafe System of High-Power Laser Using Dual Fiber Bragg Gratings.

Phase-modulated (PM) spectral failsafe systems are necessary to promptly terminate amplification processes following accidental seeding of a high-power laser chain with a non-PM pulse to prevent optical damage. In this work, we present a reliable spectral failsafe system that can indicate the presence or absence of sufficient PM light. This requirement is met by combining dual temperature-sensitive fiber Bragg gratings detection with high-speed RF amplitude comparisons.

Ultrafast convergent power-balance model for Raman random fiber laser with half-open cavity.

The power-relevant features of Raman random fiber laser (RRFL), such as lasing threshold, slope efficiency, and power distribution, are among the most critical parameters to characterize its operation status. In this work, focusing on the power features of the half-open cavity RRFL, an ultrafast convergent power-balance model is proposed, which highlights the physical essence of the most common RRFL type and sharply reduces the computation workload. By transforming the time-consuming serial calculation to a parallel one, the calculation efficiency can be improved by more than 100 times.

Off-axis eight-pass neodymium glass laser amplifier with high efficiency and excellent energy stability.

A new relay-imaged off-axial eight-pass laser amplifier with several joules energy and 1 Hz repetition rate was demonstrated. The extraction efficiency and pulse-to-pulse energy stability were greatly improved. Under the single-pass small-signal gain of 3.

Temporal pulse precisely sculpted millijoule-level fiber laser injection system for high-power laser driver.

A fiber laser injection system used as a seeder for a high-power laser facility of inertial confinement fusion was designed to meet stringent requirements. Herein, we demonstrate the fiber laser injection system, whose output single-pulse energy reaches the millijoule class. With two-stage amplitude modulators, the system produces a pulse with a higher pulse shaping capability.

Coherent Φ-OTDR based on I/Q demodulation and homodyne detection.

We demonstrate a novel distributed acoustic sensing (DAS) system based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). Both the phase and the amplitude of the Rayleigh scattering (RS) light can be demodulated in real-time. The technique is based on I/Q demodulation and homodyne detection using a 90° optical hybrid.

Cascaded random distributed-feedback Raman fiber laser assisted by Fresnel reflection.

We propose a new type of cascaded random distributed- feedback Raman fiber laser (RD-RFL), with the linear output at the second-order Stokes wavelength. The guideline about building such a RD-RFL with particular output power and conversion efficiency is presented based on numerical study. We also experimentally instantiate the principle, and confirm the effectiveness of the scheme on lasing generation.

Role of the mirror's reflectivity in forward-pumped random fiber laser.

In this paper, we thoroughly analyze the role of the point reflector's reflectivity in the performance of forward-pumped random fiber laser, in both the long- and short-cavity cases. The results show that the power performance is sensitive to the small reflection added on the pump side of the fiber end, whereas both the power distribution and threshold tend to be stable when the reflectivity reaches a relatively high level (>0.4).

Broadband flat-amplitude multiwavelength Brillouin-Raman fiber laser with spectral reshaping by Rayleigh scattering.

In this letter, we propose a novel configuration for generating multiwavelength Brillouin-Raman fiber laser (MBRFL). The spectral reshaping effect introduced by Rayleigh scattering in a 50 km single mode fiber unifies the generated Brillouin comb in terms of both power level and linewidth. As a consequence, we are able to obtain a 40 nm flat-amplitude MBRFL with wide bandwidth from 1557 nm to 1597 nm covering >500 Stokes lines.

Third-order random lasing via Raman gain and Rayleigh feedback within a half-open cavity.

Third-order random lasing operating in 1670 nm spectral band is experimentally demonstrated for the first time to the best of our knowledge, with only 2.45 W pump threshold. The lasing cavity is formed by G.