Supercontinuum generation using continuous-wave multiwavelength pumping and dispersion management

We experimentally demonstrate that continuous-wave supercontinuum generation in optical fibers can be significantly enhanced by using both multiwavelength pumping and dispersion management. We show by detailed spectral analysis that continuum enhancement is achieved mainly through a combination of Raman-assisted modulation instabilities, soliton compression, and dispersive wave generation. With this technique, an 800 nm wide (from 1.2 to 2.0 microm) 2 W supercontinuum source is reported that uses a three-wavelength pump and a dispersion-tailored four-optical fibers arrangement.     

Asymptotic modeling of linearly piezoelectric slender rods

The piezoelectric thin plate modeling already derived by the authors is extended to rod-like structures. Two models corresponding to sensor or actuator behavior are obtained. The conditions of existence of non-local terms in the limit models are discussed. To cite this article: T. Weller, C. Licht, C. R. Mecanique 336 (2008).     

Dynamic measurement of room impulse responses using a moving microphone

A technique for the recording of large sets of room impulse responses or head-related transfer functions is presented. The technique uses a microphone moving with constant speed. Given a setup (e.g., length of the room impulse response), a careful choice of the recording parameters (excitation signal, speed of movement) leads to the reconstruction of all impulse responses along the trajectory. In the case of a moving microphone along a circle, the maximal angular speed is given as a function of the length of the impulse response, its maximal temporal frequency, the speed of sound propagation, and the radius of the circle. As a result of the presented algorithm, head-related transfer functions sampled at 44.1 kHz can be measured at all angular positions along the horizontal plane in less than 1 s. The presented theory is compared with a real system implementation using a precision moving microphone holder. The practical setup is discussed together with its limitations.     

Self-induced modulational instability laser revisited: normal dispersion and dark-pulse train generation

We study theoretically and experimentally the so-called self-induced modulational instability laser and show that the passive mode-locking mechanism that is at play in this laser relies on a dissipative four-wave mixing process that leads to generation of a dark-pulse train in the normal-dispersion regime.     

Mathematical modeling of piezomagnetoelectric thin plates

We present the outline of the rigorous mathematical derivation of linearized piezomagnetoelectric thin plate models and focus on the results it leads to. It is in particular shown how four different models emerge from theoretical tools. New mixed ‘senso-actuator’ and ‘actuato-sensor’ behaviors appear. Moreover, the influence of all the 45 crystal symmetry classes on our models is described. We point out the extremely important structural switch-off phenomenon for which the electromagnetoelastic coupling disappear for some specific crystal classes.     

Inclusion of C60 into an adjustable porphyrin dimer generated by dynamic disulfide chemistry

A new, highly flexible porphyrin dimer was isolated in preparative scale from a dynamic disulfide library; this receptor adjusts to fit guests with a wide range of steric requirements and, whilst C60 proved to be an unsuitable template for this library, a new C60-porphyrin complex was isolated and characterised.     

Dynamic synthesis of a macrocycle containing a porphyrin and an electron donor

New macrocycles incorporating a porphyrin and a [small pi] electron-rich aromatic were prepared from a dynamic disulfide library. The outcome could be influenced by use of templates.