J.Y. Allain

Bio: J.Y. Allain is an academic researcher from CNET. The author has contributed to research in topics: Fiber laser & Lasing threshold. The author has an hindex of 13, co-authored 18 publications receiving 1022 citations.

Blue upconversion fluorozirconate fibre laser

Abstract: Upconversion lasing is obtained at 455 and 480 nm in a Tm3+-doped fluorozirconate fibre co-pumped at 676.4 and 647.1 nm. Lasing at 1.51 μm by two-photon absorption is also observed. Pumping schemes and dynamics of the lasing transitions are clarified.

Blue upconversion fluorozirconate fibre laser

Abstract: Upconversion lasing is obtained at 455 and 480 nm in a Tm3+-doped fluorozirconate fibre co-pumped at 676.4 and 647.1 nm. Lasing at 1.51 μm by two-photon absorption is also observed. Pumping schemes and dynamics of the lasing transitions are clarified.

Tunable green upconversion erbium fibre laser

Abstract: 50mW of green power and slope efficiency against launched pump power of 15% have been obtained at room temperature in an erbium doped fluorozirconate fibre pumped at 0.97μm. Lasing tunability domain, pump wavelength tunability and the role of colasing at 1.55μm are described.

Tunable CW lasing around 0.82, 1.48, 1.88 and 2.35 μm in thulium-doped fluorozirconate fibre

Abstract: Tunable CW operation of a thulium-doped fluorozirconate fibre laser around 0.82 μm, 1.48 μm, 1.88 μm and 2.35 μm is reported. The fibre is single mode above 1.7 μm. Laser dynamics and competition or collaboration between these wavelengths are examined.

Tunable CW lasing around 610, 635, 695, 715, 885 and 910 nm in praseodymium-doped fluorozirconate fibre

Abstract: CW lasing operation of a praseodymium-doped fluorozirconate fibre laser at 610, 635, 695, 715, 885 and 910 nm is reported, together with large tunability domains around these wavelengths. Output powers in excess of 20 mW at 610 nm, 50 mW at 715 nm and 100 mW at 635 nm, with a photon efficiency larger than 50%, have been obtained.

Upconversion and Anti-Stokes Processes with f and d Ions in Solids

Abstract: Before the 1960s, all anti-Stokes emissions, which were known to exist, involved emission energies in excess of excitation energies by only a few kT. They were linked to thermal population of energy states above excitation states by such an energy amount. It was the well-known case of anti-Stokes emission for the so-called thermal bands or in the Raman effect for the well-known anti-Stokes sidebands. Thermoluminescence, where traps are emptied by excitation energies of the order of kT, also constituted a field of anti-Stokes emission of its own. Superexcitation, i.e., raising an already excited electron to an even higher level by excited-state absorption (ESA), was also known but with very weak emissions. These types of well-known anti-Stokes processes have been reviewed in classical textbooks on luminescence.1 All fluorescence light emitters usually follow the well-known principle of the Stokes law which simply states that excitation photons are at a higher energy than emitted ones or, in other words, that output photon energy is weaker than input photon energy. This, in a sense, is an indirect statement that efficiency cannot be larger than 1. This principle is

Fiber Bragg gratings

Abstract: Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed.

Up-converting reporters for biological and other assays using laser excitation techniques

Abstract: The invention provides methods, compositions, and apparatus for performing sensitive detection of analytes, such as biological macromolecules and other analytes, by labeling a probe molecule with an up-converting label The up-converting label absorbs radiation from an illumination source and emits radiation at one or more higher frequencies, providing enhanced signal-to-noise ratio and the essential elimination of background sample autofluorescence The methods, compositions, and apparatus are suitable for the sensitive detection of multiple analytes and for various clinical and environmental sampling techniques

Ytterbium-doped silica fiber lasers: versatile sources for the 1-1.2 /spl mu/m region

Abstract: Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from /spl sim/800 nm to /spl sim/1064 nm for absorption and /spl sim/970 nm to /spl sim/1200 nm for emission. The simplicity of the level structure provides freedom from unwanted processes such as excited state absorption, multiphonon nonradiative decay, and concentration quenching. These fiber lasers therefore offer a very efficient and convenient means of wavelength conversion from a wide variety of pump lasers, including AlGaAs and InGaAs diodes and Nd:YAG lasers. Efficient operation with narrow linewidth at any wavelength in the emission range can be conveniently achieved using fiber gratings. A wide range of application for these sources can be anticipated. In this paper, the capabilities of this versatile source are reviewed. Analytical procedures and numerical data are presented to enable design choices to be made for the wide range of operating conditions. >

Whispering gallery microcavity lasers

Abstract: Whispering gallery mode (WGM) optical microresonators have attracted intense interests in the past decades. The combination of high quality factors (Q) and small mode volumes of modes in WGM resonators significantly enhances the light-matter interactions, making them excellent cavities for achieving low threshold and narrow linewidth lasers. In this Review, the progress in WGM microcavity lasers is summarized, and the laser performance considering resonator geometries and materials as well as lasing mechanisms is discussed. Label-free detection using WGM resonators has emerged as highly sensitive detection schemes. However, the resolution is mainly limited by the cavity Q factor which determines the mode linewidth. Microcavity lasers, due to their narrow laser spectral width, could greatly improve the detection resolution. Some recent developments in sensing using microcavity lasers are discussed.