A high pulse energy and high power all-fiber-optic single frequency laser at 1572 nm has been demonstrated and delivered for CO2 LIDAR applications. The main amplifier is made with the company's ...proprietary large mode area highly erbium-doped silicate glass fiber with a core diameter of 50 μm. The pump laser is a high power 1480 nm Raman fiber laser. A maximum pulse energy of 2.2 mJ has been achieved at 2.5 kHz pulse repetition rate with diffraction limited beam quality, which is the highest pulse energy and average power combination for an all-fiber based laser at 1572 nm to the best of our knowledge. For purpose of extended lifetime and consistent performance, the output pulse energy from the delivered unit was limited to 1.8 mJ with a pulse duration of ~600 ns, corresponding to a peak power of ~3.0 kW.
We propose an energy transfer model with a cubic atomic population dependence to accurately model the behavior of various reported high-power erbium-doped fluoride fiber lasers operating near 2.8 ...microns. We first show that the previously introduced weakly interacting (WI) and strongly interacting (SI) models are not adequate for precisely modeling such high-power erbium-doped fluoride fiber lasers. We compare results obtained with the WI and SI models to the proposed model by simulating 4 different highly doped (7 mol.%) fiber lasers previously reported in the literature. Laser efficiencies and powers are reproduced with great accuracy. In addition, four other fiber laser systems based on erbium concentrations varying from 1-6 mol.% are also simulated with good accuracy using the proposed model with the exact same set of spectroscopic parameters, which confirms its validity for various erbium doping concentrations. Redshifting of laser wavelength is also taken into account by considering the full cross section spectra and computing signal powers over several wavelength channels.
This study proposed a high-quality fiber ring laser combining four-subring resonators and a saturable absorber within a ring cavity. An un-pumped erbium-doped fiber is introduced as the saturable ...absorber (SA) within the ring structure. By employing the vernier effect, we arrange four subrings with different lengths to form the four-subring resonators, achieving a single-longitudinal-mode (SLM) operation. At a pump power of 100 mW, the laser output power and wavelength deviations during a one-hour test were measured to be 0.01 dB and 0.059 nm, respectively. Additionally, using the delayed self-heterodyne measurement system and Lorentzian fit analysis, we measured an ultra-narrow linewidth of 623.1 Hz.
Compared with Yb, Nd has potential in 1120 nm fiber lasers, with the characteristics of larger emission cross section and four-level structure. In this work, Nd-doped fiber (NDF) oscillator and ...Nd-Raman fiber (NRF) oscillator were built using single-mode 5/125 NDF to study the lasing characteristics at 1120 nm, especially the suppression of amplified spontaneous emission at 1060 nm. Limited by the parasitic oscillation at 1060 nm, the NDF oscillator achieved 5 W output at 1120 nm. The NRF oscillator removed the limitation due to the Raman shift from 1064 nm to 1120 nm and obtained an output of 7.7 W at 1120 nm with a spectral peak-to-peak contrast of 36 dB. This work provides experimental basis for the application of NDF in 1.1 μm.
In this Letter, we used a home-made high-power and -brightness random Raman fiber laser (RRFL) at <inline-formula> <tex-math notation="LaTeX">1.69~\mu \text{m} </tex-math></inline-formula> as the ...pump to demonstrate free-running and widely tunable operations of dysprosium (Dy)-doped ZrF 4 fiber laser in the 3 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> mid-infrared (MIR) region. In an optimal F-P cavity arrangement, the maximum output power of 1.92 W with a slope efficiency of 18.3% was achieved at 2.992 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>, indicating the highest power level of Dy fiber lasers under near-infrared (NIR) pumping. Using a modified scheme, in which a ruled diffraction grating (RDG) in a Littrow configuration was adopted as the wavelength selector and output coupler, the laser wavelength could be continuously tuned in the >700 nm range of <inline-formula> <tex-math notation="LaTeX">2.710\sim 3.415~\mu \text{m} </tex-math></inline-formula>, almost entirely covering the emission bands accessed by erbium (Er) and holmium (Ho) ions in this region. To our knowledge, this is the widest level (in terms of wavelength domain), to date, from not only a Dy laser, but a rare-earth-doped laser at any wavelengths. Additionally, the possibility of further extending the tuning range has been also predicted by preliminary modeling, validated by the experimental data. These results highlight the great potential of this NIR pumped Dy fiber laser for developing high-performance coherent source at <inline-formula> <tex-math notation="LaTeX">\sim 3~\mu \text{m} </tex-math></inline-formula>.
•The tapered fiber-graded-index multimode fiber-tapered fiber acts as a SA.•The dual-wavelength mode-locking is achieved.•The switchable harmonic solitons molecules is obtained.
We report a ...switchable single wavelength and dual-wavelength all-fiber ultrafast mode-locked lasers based on nonlinear multimode interference (NL-MMI) effect of graded-index multimode fiber (GIMF). The saturable absorber (SA) used in the laser is composed of tapered fiber-GIMF-tapered fiber. The use of tapered fibers not only reduces the dependence on the length of GIMF, but also simplifies the fabrication of SA. The modulation depth of the SA was measured to be 9%. By adjusting intra-cavity loss and the polarization controllers properly, traditional switchable single wavelength and dual-wavelength mode-locking can be realized. Meanwhile, a single wavelength harmonic soliton molecule mode-locking can be observed, and the central wavelength with the same modulation period can be switched between 1558 nm and 1531 nm. Such a switchable harmonic soliton molecules mode-locked laser with wide wavelength intervals could be useful in measuring chemical reactions, and has rarely been reported.
We experimentally demonstrated the harmonic mode-locking (HML) dissipative soliton resonance (DSR) pulses in an erbium-doped fiber laser with large normal dispersion utilizing an optical integrated ...module (OIM) mode locked by nonlinear polarization rotation (NPR) technique. With fixed intra-cavity parameters, various HML operations in the DSR regimes are available through adjusting the polarization controller (PC). Triggered by extra filtering loss due to broadened spectra under the stronger pump power or variations of polarization states, the multi-pulsing operation in the cavity assisted by pulse self-organizing enables the fundamental mode-locking (FML) DSR pulses to transform into HML conditions, where the newly formed HML DSR pulses are evolving in the same characteristics as the FML DSR pulses during each harmonic order. Under specific polarization states, the harmonic order is able to increase sequentially as the pump power ramps up with spectral redshift. Further tuning the PCs at a strong pump power will enable other harmonic states, of which the order could be up to 17th.
Coherent Beam Combination of Ultrafast Fiber Lasers Klenke, Arno; Muller, Michael; Stark, Henning ...
IEEE journal of selected topics in quantum electronics,
2018-Sept.-Oct., 2018-9-00, Volume:
24, Issue:
5
Journal Article
Peer reviewed
Open access
The performance of fiber laser systems has drastically increased over recent decades, which has opened up new industrial and scientific applications for this technology. However, currently a number ...of physical effects prevents further power scaling. Coherent combination of beams from multiple emitters has been established as a power scaling technique beyond these limitations. It is possible to increase the average power, and for pulsed laser systems, also parameters such as the pulse energy and the peak power. To realize such laser systems, various aspects have to be taken into account that include beam combination elements, stabilization systems, and the output parameters of the individual amplifiers. After an introduction to the topic, various ways of implementing coherent beam combination for ultrashort pulses are explored. Besides the spatial combination of beams, the combination of pulses in time will also be discussed. Recent experimental results will be presented, including multidimensional (i.e., spatial and temporal) combination. Finally, an outlook on possible further developments is given, focused on scaling the number of combinable beams and pulses.
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