We report on the use of OH diffusion barrier coatings to suppress fiber tip degradation in high-power 3 μm fiber lasers. To this extent, silicon nitride thin-films are sputtered on the endface of a 20 W erbium-doped fluoride fiber laser at 2.83 μm. By monitoring the temperature evolution of the output fiber tip over a 24 hour time period, we validate the effectiveness of silicon nitride thin films in mitigating fiber tip degradation. These results, along with previous demonstrations, underline the potential of 3 μm fiber lasers to reach 100 W of output power in the near future.
Novel ultrafast sources based on fluoride fiber lasers and amplifiers have emerged as a new alternative for the efficient generation of coherent broadband signal in the mid-infrared (> 3 µm). It was shown recently that the amplification of a 2.8-µm ultrafast signal using Er3+: fluoride fiber leads to different output regimes in the mid-infrared (supercontinuum or tunable femtosecond pulses) depending on the input signal properties. Here, we study the underlying mechanisms that affect the amplification and spectral conversion dynamics of ultrashort pulses inside such amplifier through a complete numerical model based on accurate measurements of the amplifier properties. The numerical results, which are in very good agreement with the experiment, show an enhanced output stability due to the attractor properties of the amplifier and the possibility of generating a supercontinuum extending from 2.8 to 4.2 µm with more than 4 W of average power using off-the-shelf fluorozirconate fibers. By designing the appropriate amplifier, tunable and spectrally isolated femtosecond solitons with peak power up to 400 kW around 3.4 µm that can be shifted up to 4 µm could also be achieved. Future perspectives with novel mid-IR laser transitions and different fluoride glass compositions with extended transmission are also discussed.
Optical fiber lasers offers the advantage of being relatively compact and efficient. However, the materials such as fluoride
and chalcogenide glasses used for their fabrication must be exempt of defects in order to make efficient laser systems.
However, most existing quality control techniques are not compatible with chalcogenide fibers because of their limited
transparency in the visible spectral range. For this reason, the Université Laval’s Centre d’optique, photonique et laser
(COPL), in Quebec City, Canada, has developed a novel non-destructive testing (NDT) methodology based on infrared
imaging to address this problem. The results show how this simple screening technique eases the selection of high-quality
fibers for the design of high-power mid-IR lasers.
Optical fiber lasers offers the advantage of being relatively compact and efficient. However, the materials such as fluoride and chalcogenide glasses used for their fabrication must be exempt of defects in order to make efficient laser systems. However, most existing quality control techniques are not compatible with chalcogenide fibers because of their limited transparency in the visible spectral range. For this reason, the Université Laval's Centre d'optique, photonique et laser (COPL), in Quebec City, Canada, has developed a novel non-destructive testing (NDT) methodology based on infrared imaging to address this problem. The results show how this simple screening technique eases the selection of high-quality fibers for the design of high-power mid-IR lasers.
The recent development of soliton femtosecond fiber lasers emitting at 2.8 μm opens a new avenue for the generation of ultrashort pulses in the mid-infrared spectral region. In this paper, we investigate the peak power scalability of such lasers. By optimizing the output coupling ratio and the length of the Er3+: fluoride fiber in the cavity, we demonstrate the generation of 270-fs pulses with an energy of 7 nJ and an estimated peak power of 23 kW. These record performances at 2.8 μm surpass by far those obtained from standard soliton lasers at 1.55 μm. A numerical model of the laser including the effect of the intracavity atmospheric absorption is also presented. Numerical simulations agree well with the experimental results and suggest that the atmospheric propagation in the cavity could prevent the laser from self-starting in a mode-locked regime. This femtosecond laser could be the building block for simple and compact mid-infrared frequency combs and supercontinuum sources.
A growing number of applications are calling for compact laser sources operating in the mid-infrared spectral region. A review of our recent work on monolithic fiber lasers (FL) based either on the use of rare-earth fluoride fibers or on Raman gain in both fluoride and chalcogenide glass fibers is presented. Accordingly, an erbium-doped double clad fluoride glass all-FL operating in the vicinity of 3 μm is shown. In addition, we present recent results on the first demonstrations of both fluoride and chalcogenide Raman fiber lasers operating at 2.23 and 3.34 μm, respectively. It is shown that based on this approach, monolithic FLs could be developed to cover the whole 2 to 4 μm spectral band.
A growing number of applications are calling for compact laser sources operating in the mid-infrared spectral region. A review of our recent work on monolithic fiber lasers based either on the use of rare-earth fluoride fibers or on Raman gain in both fluoride and chalcogenide glass fibers is presented. Accordingly, an erbium-doped double clad fluoride glass all-fiber laser operating in the vicinity of 3 μm is shown. In addition, we present recent results on the first demonstrations of both fluoride and chalcogenide Raman fiber lasers operating at 2.23 μm and 3.34 μm, respectively. It is shown that based on this approach, monolithic fiber lasers could be developed to cover the whole 2-4 μm spectral band.
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