Abstract: We have invented a set of calculation and display methods for polarized light using a representation that we call the Hybrid Polarization Sphere (HPS). The HPS incorporates the Poincaré Sphere and its dual, the Observable Polarization Sphere (OPS). The HPS uses a four-pole spherical polar coordinate system to map the transformation of the state(s) of polarization (SOP) of a beam of light as the beam propagates through one or more polarizing elements (polarizer, waveplate, or rotator). A simple computing aid based on the HPS leads to methods for solving optical polarization problems directly by visual measurement and interpolation. These avoid both the linear algebra and trigonometry of the underlying mathematics and the external apparatus needed to use the Poincaré Sphere for computing phase shifts. Furthermore, simulating and animating these methods on an electronic graphical display produces helpful visual explanations of numerical solutions to polarization problems.

Abstract: High output power, high gain, and low noise are achieved in a two-stage optical amplifier, suitable for use as a repeater for a long haul lightwave communication system, in accordance with the principles of the invention, by employing a first amplifying stage having a signal gain sufficiently small to prevent self-saturation by amplified stimulated emission (ASE) that uses counter-propagating pump light to cause maximum inversion of the first stage amplifying medium. In an illustrative embodiment of the invention, EDFAs are used in each of two amplifying stages. The length of the EDFA in the first stage is short enough to ensure nearly complete inversion of the EDFA from pump light that counter-propagates with the signal. The counter-propagating pump light allows the invention to advantageously avoid the significant noise figure penalty from the input loss associated with co-propagating pump light.

Abstract: The placement of one or a pair of suitably biased thin semiconductor epital layers on the secondary emission surface of a multipactor device provides an improvement of devices which operate in accordance with the principle of multipactoring. A multipactor device is disclosed having a multipactor region comprised of at least one surface formed of one or more thin epitaxial semiconductor layers, the outer layer being of n-type semiconductor material consisting of, for example, gallium phosphide covered with cesium which provides an abundance of free electrons at the surface when biased in the forward direction. In one disclosed configuration the multipactor region is located in a section of waveguide while in another arrangement the region is located on the top of a post in a multipactor input cavity.