Abstract: Sets of power amplifier branches (which comprise an RF/microwave amplifier stage) are power combined within each stage and each set of power amplifier branches are biased in different classes of operation by bias circuits possessing different impedance characteristics such that the fundamental frequency components present at the output are in-phase with one another and the IMD3 components are anti-phase over a broad range of power levels. The RF input signal is provided by the output of the previous stage of the RF/microwave amplifier. The output of each stage is formed by power combining sets of these power amplifier branches, each of which are separately biased, so the fundamental components are additive resulting in the maximum possible output power and the IM3 components cancel partially or completely.

Abstract: Electrical conduits and conductors may be sealed using a chamber configured for attachment to a conduit through which at least one conductor runs such that the at least one conductor also runs through the chamber. A vent allows gas that enters the chamber from the conduit to exit the chamber. A sealing compound fills the chamber and surrounds the conductor and the vent.

Abstract: A Raman cell for Raman shifting of a laser pump beam, to an output beam of a different wavelength, the cell containing a gaseous Raman medium at a pressure of 100-1000 PSIG. An input window for a pump beam is located at one end of the cell and an output window for a Raman shifted wavelength output beam is located at the cells opposite end. The output window is formed as a plane mirror having an inner face coated with dielectric thin films which provide a high reflectivity for the wavelength of the pump beam and a partial reflectivity at the cell's Raman shifted wavelength. The input window includes at least one lens that forms a converging lens for the pump beam which has a focal length in the Raman medium of about 3/2 of the cell's inner length to substantially focus the pump beam at the center of the cell after it is reflected back by the inner face of the plane mirror.