All-fiber passively mode-locked femtosecond fiber lasers

10.32920/ryerson.14638536.v1 ◽

2021 ◽

Author(s):

Jiaqi Zhou

Keyword(s):

Fiber Laser ◽

Pulse Energy ◽

Pulse Width ◽

Fiber Lasers ◽

High Efficiency ◽

Single Mode ◽

Scaling Up ◽

Mode Locking ◽

Raman Signal ◽

Loop Mirror

This dissertation presents three all-fiber designs of passively mode-locked lasers in order to achieve high pulse energy, environmentally-stable dissipative soliton (DS) operation in all-normal-dispersion cavities. A numerical model for DS mode-locked fiber lasers based on the nonlinear Schrodinger equation has been used to guide the experimental designs. Firstly, an environmentally-stable and ultra-compact SESAM mode-locked fiber laser is demonstrated. The all-fiber design is realized using a mode-field-adaptor (MFA) to couple light onto the SESAM. A polarization-maintaining fiber loop mirror serves multiple functions as a highly reflective mirror, an output coupler and polarization selector. Self-starting and stable DS mode-locking operation is achieved with 1.7 nJ pulse energy and a 22 ps pulse width. Secondly, an ultra-stable DS mode-locking was demonstrated in a long cavity ring laser with a nonlinear amplified loop mirror (NALM) as a mode-locking device. The output pulses of 32 nJ, 615 fs de-chirped pulse width were obtained with the Raman signal suppressed below -20 dB in a 81 m long cavity. The mode-locking is self-starting and the mode-locked pulse train shows excellent stability. Thirdly, the mode-laser cavity was extended with a piece of large-mode-area (LMA) fiber with a low dispersion to further scaling up the pulse energy to 56.8 nJ. The laser pulses were compressed to 750 fs by a pair of volume gratings. In the processing of scaling-up the pulse energy of the NALM mode-locked fiber laser, some interesting physical phenomena were observed, such as the operation regime transition from noise-like to DS with a sudden reduction of Raman signal and a unique waves-splitting with a stable temporal spacing. The phenomena were studied and explained in this dissertation. In addition to the mode-locked fiber laser, a CW and a Q-switched fiber lasers were also designed with a single-mode- multimode- single-mode (SMS) filter as an effective mean of overcoming nonlinear effects. The transmission spectral property of the SMS was studied which fits well with theoretical calculation. One high efficiency SMS CW fiber lasers and one SMS Q-switched fiber laser were designed which showed the effectiveness of the SMS filter for inhibiting the SRS and significantly reducing SPM.

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Generation and dynamics of soliton and soliton molecules from a VSe2/GO-based fiber laser

Nanophotonics ◽

10.1515/nanoph-2021-0543 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Benhai Wang ◽

Haobin Han ◽

Lijun Yu ◽

Yueyue Wang ◽

Chaoqing Dai

Keyword(s):

Numerical Simulation ◽

Fiber Laser ◽

Saturable Absorber ◽

Pulse Width ◽

Fiber Lasers ◽

Modulation Depth ◽

Mode Locking ◽

Pulse Interval ◽

Saturable Absorption ◽

Soliton Dynamics

Abstract Recently, in addition to exploring the application of new saturable absorber devices in fiber lasers, soliton dynamics has also become a focus of current research. In this article, we report an ultrashort pulse fiber laser based on VSe2/GO nanocomposite and verify the formation process of soliton and soliton molecules by the numerical simulation. The prepared VSe2/GO-based device shows excellent saturable absorption characteristics with a modulation depth of 14.3% and a saturation absorption intensity of 0.93 MW/cm2. The conventional soliton is obtained with pulse width of 573 fs, which is currently the narrowest pulse width based on VSe2-related material, and has a signal-to-noise ratio of 60.4 dB. In addition, the soliton molecules are realized based on the VSe2/GO for the first time and have a pulse interval of ∼2.2 ps. We study the soliton dynamics through numerical simulation and reveal that before the formation of the soliton, it undergoes multiple nonlinear stages, such as soliton mode-locking, soliton splitting, and soliton oscillation. Furthermore, the results of numerical simulation are agreed well with the experimental data. These results indicate that the VSe2/GO might be another promising saturable absorber material for ultrafast photonics, and deepen the understanding of soliton dynamics in ultrafast fiber lasers.

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Passive mode locking of a neodymium-doped fiber laser with a nonlinear optical loop mirror

IEEE Journal of Quantum Electronics ◽

10.1109/3.481881 ◽

1996 ◽

Vol 32 (2) ◽

pp. 333-339 ◽

Cited By ~ 8

Author(s):

Wang-Yuhl Oh ◽

B.Y. Kim ◽

Hai-Woong Lee

Keyword(s):

Fiber Laser ◽

Nonlinear Optical ◽

Mode Locking ◽

Passive Mode ◽

Nonlinear Optical Loop Mirror ◽

Loop Mirror

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48mJ pulse energy directly from a single-mode Q-switched ytterbium fiber lasers

Optics Express ◽

10.1364/oe.438634 ◽

2021 ◽

Author(s):

Monica Kalichevsky-Dong ◽

Wenping Ge ◽

Thomas Hawkins ◽

Turghun Matniyaz ◽

Liang Dong

Keyword(s):

Pulse Energy ◽

Fiber Lasers ◽

Single Mode

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All-fiber passively Q-switched ytterbium doped double-clad fiber lasers: experiment And modeling.

10.32920/ryerson.14656230 ◽

2021 ◽

Author(s):

Yi Lu

Keyword(s):

Pulse Energy ◽

Traveling Wave ◽

Pulse Width ◽

Fiber Lasers ◽

Peak Power ◽

Wave Model ◽

Core Size ◽

The Core ◽

Q Switching ◽

Output Characteristics

All-fiber passively Q-switched lasers were demonstrated using ytterbium-doped double cladding fiber (YDF) as an active medium. The laser was pumped by three 25W, 975nm fiber coupled diodes and Q-switching was initiated when the amplified spontaneous emission generated in the core of the gain fiber bleached the saturable absorber (SA). A piece of samarium-doped fiber was used as SA in first configuration and pulses with 68μJ pulse energy and 210ns pulse width were obtained. In second configuration, a piece of ytterbium-doped fiber with much smaller core size was used as SA to produce pulse energy of 86μJ. The last configuration incorporated a 9m-long YDF as gain fiber. The far end from pump was acting as SA in this case and pulses with 82μJ pulse energy and 148ns pulse width were observed. The peak power was estimated at 554W. Traveling wave model was implemented to numerically simulate the output characteristics versus pump power.

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Environmentally stable Er-fiber mode-locked pulse generation and amplification by spectrally filtered and phase-biased nonlinear amplifying long-loop mirror

High Power Laser Science and Engineering ◽

10.1017/hpl.2019.29 ◽

2019 ◽

Vol 7 ◽

Cited By ~ 2

Author(s):

Zhengru Guo ◽

Qiang Hao ◽

Junsong Peng ◽

Heping Zeng

Keyword(s):

Repetition Rate ◽

Fiber Lasers ◽

Fiber Amplifier ◽

Mode Locking ◽

Pulse Generation ◽

Erbium Doped ◽

Polarization Maintaining Fiber ◽

Fiber Mode ◽

Polarization Maintaining ◽

Loop Mirror

We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers, which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop mirrors. By employing 100-m polarization-maintaining fiber (PMF) in the nonlinear loop, the fundamental repetition rate reaches 1.84 MHz and no practical limitation is found to further decrease the repetition rate. The filter used in the long loop not only suppresses Kelly sidebands of the solitons, but also eliminates the amplified spontaneous emission which exists widely in low-repetition-rate ultrafast fiber lasers. The bandwidth of the filter is optimized by using a numerical model. The laser emits approximately 3-ps pulses with an energy of 17.4 pJ, which is further boosted to $1.5~\unicode[STIX]{x03BC}\text{J}$ by using a fiber amplifier.

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