A three dimensional investigation of two dimensional orbits

Orbits in the principal planes of triaxial potentials are known to be prone to unstable motion normal to those planes, so that three dimensional investigations of those orbits are needed even though they are two dimensional. We present here an investigation of such orbits in the well known logarithmic potential which shows that the third dimension must be taken into account when studying them and that the instability worsens for lower values of the forces normal to the plane. Partially chaotic orbits are present around resonances, but also in other regions. The action normal to the plane seems to be related to the isolating integral that distinguishes regular form partially chaotic orbits, but not to the integral that distinguishes partially from fully chaotic orbits.Comment: Accepted for publication in CMD

Photonics-based millimeter and terahertz wave generation using a hybrid integrated dual DBR polymer laser

The generation of high frequency signals into the terahertz range is dominated by photonics-based systems pushing the development of ultra-broadband wireless communication links. Recently, photonic integrated circuits have been proposed to implement different photonic signal generation techniques offering different semiconductor laser structures. Here we present for the first time a dual wavelength source for optical heterodyning based on hybrid integration of active InP elements and thermo-optically tunable polymer waveguide structures. The chip integrates two external cavity lasers, each with an InP gain chip coupled to a polymer phase and Bragg gratings sections, combined with a Y-junction. Each laser has a wavelength tuning range over 20 nm, enabling the generation of signals from tenths of GHz up to several THz with MHz resolution. We demonstrate the generation of a 330-GHz free-running beat-note has a linewidth of few MHz ( â¼3 MHz)