Jean-Francois Marcerou

General theoretical approach describing the complete behavior of the erbium-doped fiber amplifier

A theoretical analysis of the erbium-doped fiber amplifier completely describes this device. This modeling is developed within the most attractive configurations : 1. 48im and O. 98im pump wavelengths. The original approach used to take into account the amplified spontaneous emission (ASE) enables us to fully characterize the amplifier at any pump and signal regime. Thus we may quantitavely predict the influence of optogeometrical parameters erbium distribution and spectroscopic properties pump and signal powers and wavelengths and amplifier lengths over the amplifier performances in terms of gains residual pump powers co- and counter-propagating ASE frequency components. The agreement between predictive calculations and experiments appears truly excellent. Moreover this original ASE modeling results in noise figures compelling with published experiments and this analysis may also be used for superfluorescent sources design. Due to its quantitative nature this numerical tool can be used for erbium-doped fiber optimization optimal set-up conditions for amplifier modules transmission link evaluations and network applications.

The 7F0-5D0 two-photon transition: A test of theoretical models

Abstract Measurements of the polarization dependence of the 7F0→5D0 two-photon transition for the Sm2+ ion in BaClF are reported. The standard second-order Axe theory is shown to fail in interpreting the obtained data. A phenomenological approach taking account of higher-order contributions is then followed. It turns out to reproduce the experimental results in a very satisfactory way. It is pointed out that the scalar term responsible for the isotropic contribution to the 7F0→5D0 two-photon transition intensity is not the only one to be operative in this material.

Direct two-photon excitation in some terbium materials

Abstract Direct two-photon excitation of the visible fluorescence of TbF3 have been investigated, at low temperature, using infrared pulsed laser radiations. An excellent agreement with the peak positions of the one photon absorption is reported despite of a considerable change of proportion in the line intensities.

Inhomogeneous line broadening of optical transitions in Nd3+ and Er3+ doped preforms and fibers

Summary of the main results for the fluorescence of Nd doped materialsErbium doped materials Erbium ions were excited through the , I. absorotion transition accessible with our c. w. Ti—sapohire laser, the laser excitation ranging from 950 run to 990 nm. A low noise and very sensitive Ge detector was used because of the long lifetime (lOms) of the regular infrared erbium fluorescence attributed to the I i transition. Figure 6 presents the data for the Er3 doped i5/2 areform. showing the line—narrowing effect for various excitation wavelenQths across the absorDtion band. In contrast to the Nd case, ohonon relaxation occurs to populate the metastable I level with a time ia/2 faster than the detector response. The room temoerature soectrum depicted at the top of Fig. 6 has the well known asymmetrical shape which does not depend on the excitation wavelength. A similar profilewas also obtained usinc the excitation of the green Argon laser line. At low temoerature, a drastic line narrowing is observed, the