The geometry mismatch between active and passive fibers and particularly the presence of a pedestal around the core of active fibers creates a light coupling from this pedestal to the cladding of the passive fiber when spliced together. This signal light propagating in the cladding can results in a beam degradation that reduces the laser performances. We proposed a new solution consisting in using a perfectly matched couple of fibers by adding a pedestal around the core of the passive fiber. This pedestal maintains the coupling light in a quasi-single-mode pedestal area that will not lead to any power losses and not degrade the output beam.
In this conference, we show the realization of a high power 2.12 μm Ho3+-doped fiber (HDF) laser integrating for the first time to our knowledge a 1.94 μm triple clad fiber (3CF) combiner. This 3CF combiner, specifically developed for the above mentioned HDF laser, presents low losses properties thanks to a low-index glass capillary implemented in the component. Moreover, in this contribution we will discuss the power scalability of such a HDF laser monolithic architecture based on a triple clad fiber combiner pumped at 1.94 μm using Tm3+-doped fiber lasers.
In this contribution, we show for the first time to our knowledge the realization of a high power 1.94 µm triple clad fiber combiner with low insertion losses, thanks to the implementation in the component of a low-index glass capillary. Moreover, in this contribution we discuss the power scalability of a 2.1 µm Ho3+-doped fiber laser architecture integrating the above mentioned triple clad fiber combiner and pumped at 1.94 µm using Tm3+-doped fiber lasers developed at ISL.
Thanks to a high atmospheric transmission, 2 μm fiber lasers offer unique benefits for both civil and military applications, such as LIDAR, laser weapons or optical countermeasures. All-fibered sources are of particular interest since they allow compact, robust and alignment-free systems. Furthermore, they are well-suitable for power upscaling thanks to a good thermal dissipation. We present in this contribution the recent results achieved on 2 μm fiber lasers and fibered components allowing all-fibered architectures. In particular, the power upscaling up to 500 W-class and the efficiency of Tm3+ -doped and Tm3+, Ho3+ -codoped fiber lasers are discussed.
The influence of a static electric field on a non-polar molecule has been studied by means of multiplex coherent anti-Stokes Raman scattering (M-CARS). A parallel measurement of electric field induced second harmonic generation (EFISHG) has also been led. Both techniques suggest a reorientation of the molecule due to the presence of an electric field. This phenomenon can be used to increase the chemical selectivity and the signal to non-resonant background ratio, namely, the sensitivity of the M-CARS spectroscopy.
Particle size analyzers based on laser scattering commonly make use of light diffraction and scattering around the particle considered in its medium. For particle size below 50 μm, Fraunhofer theory must be abandoned in favor of Mie model, which requires to know the complex refractive index of both the particle and the medium. In this paper, we demonstrate that particle size characterization can be realized by measuring the macroscopic Raman spectral response of the whole set of particles excited by a laser beam. We use a home-made setup based on coherent anti-Stokes Raman scattering (CARS) and having a 0.36 cm-1 spectral resolution, in which the laser source is a dual-output infrared nanosecond supercontinuum source (1064 nm monochromatic pump wave, 1100-1640 nm broadband Stokes wave). The samples are latex beads in water with different diameters (20 nm, 50 nm, 100 nm, 5 μm). The C-H stretching line around 3050 cm-1 is studied. For this vibration, we study the variation of both the CARS central frequency and linewidth as a function of the particles size. A quasi linear increase of the linewidth with the inverse of the diameter is measured. A difference of 15 cm-1 is obtained between beads with diameters of 5 μm and 20 nm respectively. The physical phenomena at the origin of this difference are discussed, especially considering the contributions of the center and of the boundaries of the object to the global Raman response.
We demonstrate all-normal dispersion supercontinuum generation in the 1080 nm-1600 nm range by propagating subnanosecond pulses in a high numerical aperture standard optical fiber. The extreme saturation of the Raman gain provides a flat spectrum in the considered range, making this broadband source particularly suitable for coherent Raman spectroscopy. This unusual regime of supercontinuum generation (Raman gain saturation regime) is investigated through an experimental spectrotemporal study. The possibility of operating spectrometer-free time-coded coherent Raman spectroscopy is introduced.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.