No Arabic abstract
We proposed a narrow spectral bandwidth Erbium-doped fiber (EDF) laser Q-switched by a homemade saturable dynamic induced grating (SDIG) which is introduced via reforming the structure of a fiber saturable absorbers FSA with a piece of EDF and a fiber Bragg grating. The SDIG integrates both saturable absorption and spectral filtering effect simultaneously, which was confirmed through theoretical analysis and experimental results for the first time, to the best of our knowledge. Further study verified that the spectral width of the Q-switched emissions is decided by the length of the SDIG and the input power of the pump source. The Q-switched pulse with the narrowest spectral width of about 29.1 pm achieved in this work is the narrowest bandwidth pulse in the domain of the FSA Q-switched fiber lasers when the length of SDIG and pump power are 20 cm and 250 mW, respectively. Our method provides a simple way to obtain the Q-switched pulses with narrow bandwidths, which have promising applications for nonlinear frequency conversion, Doppler LIDAR and coherent beam combinations.
Generally speaking, the self-sweeping effect relies on the dynamical grating formed in a gain fiber. Here, the normal self-sweeping was generated in a pump-free ytterbium-doped fiber which serves as a fiber saturable absorber and is introduced to the laser cavity by a circulator in this experiment. The sweeping rate and the sweeping range alter as usual, both of which can be controlled by the pump power. Further, a new self-pulse signal is observed and discussed in this work, which shows the difference of the self-sweeping effects between active fiber and fiber saturable absorber.
Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multi-layer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 {mu}m. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 {mu}J/cm2, respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 {mu}J and pulse width of 1.18 {mu}s at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-{mu}m fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.
We present a laser frequency comb based upon a 250 MHz mode-locked erbium-doped fiber laser that spans more than 300 terahertz of bandwidth, from 660 nm to 2000 nm. The system generates 1.2 nJ, 70 fs pulses at 1050 nm by amplifying the 1580 nm laser light in Er:fiber, followed by nonlinear broadening to 1050 nm and amplification in Yb:fiber. Extension of the frequency comb into the visible is achieved by supercontinuum generation from the 1050 nm light. Comb coherence is verified with cascaded f-2f interferometry and comparison to a frequency stabilized laser.
The commercialization of lithium niobate on insulator (LNOI) wafer has sparked significant on-chip photonic integration application due to its remarkable photonic, photoacoustic, electro-optic and piezoelectric nature. A variety of on-chip LNOI-based optical devices with high performance has been realized in recent years. Here we developed 1 mol% erbium-doped LN crystal and its LNOI wafer, and fabricated an erbium-doped LNOI microdisk with high quality ($ sim $ 1.05$times 10^{^5}$ ). C-band laser emission with $ sim $1530 nm and $ sim $1560 nm from the high-Q erbium-doped LNOI microdisk was demonstrated both with 974 nm and 1460 nm pumping, and the latter has better thermal stability. This microlaser would play an important role in the photonic integrated circuits of lithium niobate platform.
We investigate the buildup dynamics of broadband Q-switched noise-like pulse (QS-NLP) driven by slow gain dynamics in a microfiber-based passively mode-locked Yb-doped fiber laser. Based on shot-to-shot tracing of the transient optical spectra and qualitatively reproduced numerial simulation, we demonstrate that slow gain dynamics is deeply involved in the onset of such complex temporal and spectral instabilities of QS-NLP. The proposed dynamic model in this work could contribute to deeper insight of such nonlinear dynamics and transient dynamics simulation in ultrafast fiber laser.