Abstract: Two approaches are provided for achieving an optical amplifier system capable of producing high peak power, high energy pulse outputs while suppressing scattering noise. The first approach relates to an optical amplifier system which has at least one laser diode pulsed or cw pumped double clad fiber amplifier utilized for receiving a high frequency modulated injected signal pulse of short duration from the laser diode, via the fiber core, for amplification by coupling pump light into the inner cladding of the fiber. The average signal power is sufficient to saturate the gain of the fiber so as to minimize significant onset and buildup of forward and backward scattering noise. The duty cycle of the injected signal source pulse is chosen to allow adequate gain recovery in the fiber amplifier between pulses.

Abstract: A method of fabricating an integrated circuit with trenches, without parasitic edge transistors, for isolating FET transistors from each other without degrading the FETs operating characteristics by junction leakage, breakdown or shorting when a metal silicide is used in the source/drain regions. A silicon wafer, is formed with a gate electrode material on a gate insulating layer before forming the trenches for isolation. Now, with an etch protective layer on the gate electrode, trenches are etched and filled with an insulating material in the gate electrode material, the gate insulating layer and the silicon wafer to isolate the active regions. After the gate electrode material is etched to define the gate electrodes, the tops of gate electrodes are in essentially the same plane as the tops of the trenches. Preferably in the fabrication process, sidewalls are formed on the walls of the trenches and the gate electrodes.

Abstract: An optical amplifier pumping system with built-in redundant reliability for lightwave communication system provides plural levels of redundancy. A first level of redundancy deals with redundancy in the form of plural primary laser diode sources in the lightwave communication system. A second level of redundancy deals with redundancy of multiple single mode laser emitters on the same chip or bar sufficiently segmented so as not to interfere with operation of or cause failure to adjacent or neighboring emitters on the same chip or bar. A third level of deals with redundancy of a plurality of fiber pump sources for pumping a plurality of serially connected injection signal fiber amplifiers.

Abstract: An upconversion fiber laser uses a pump source which may be another fiber laser, such as a high power, diode-laser-pumped, fiber laser. The upconversion fiber laser includes an optical fiber whose core region is doped with an active lasing ionic species capable when optically pumped of undergoing upconversion excitation, such as certain rare earth ionic species, and which is embedded in a cladding of the optical fiber. Use of a fiber pump laser can improve coupling of pump light into the optical fiber, thereby achieving higher pump intensities in the core region and improved upconversion efficiency. The upconversion fiber laser's resonant laser cavity is defined by feedback means which can include at least one reflective grating formed in the optical fiber, as well as a reflective end face of the optical fiber.

Abstract: In an optical transmission medium, such as a fiber amplifier, two optically distinguishable signals with complementary modulation are both inputted into the amplifying medium for encoding information, particularly a serial stream of digital data, or alternatively, redundant encoding of pulses. The gain profile in the medium is preferably maintained approximately constant at all times, so that whichever amplified signal is used as the primary information carrier, its output intensity will be substantially stable from pulse to pulse, independent of recent pulse history. The two complementary signals may have different orthogonal linear polarizations or wavelengths with the same stimulated emission cross-section, so that the population inversion profile stays constant, whichever signal happens to be on at a given moment.

Abstract: An upconversion fiber laser with a double-clad fiber is pumped with a laser-diode-based laser pump source, the inner cladding of the fiber forming a low transmission loss waveguide for the pump light. The central core of the fiber is doped with an active lasing ionic species capable of undergoing upconversion excitation, such as certain rare earth ionic species. The use of a double-clad fiber permits the use of high power, high brightness laser diodes, including those with broad emitting apertures, as well as high power diode laser pumped fiber lasers, as the pump source, thereby achieving higher pump intensities within the upconversion laser fiber and improved upconversion efficiency. Pump brightness can be further increased with multiple pump schemes which use multiple pump wavelengths in different absorption bands, multiple pump wavelengths within the same absorption band, pump light from pairs of cross-polarized sources, and pumping from both ends of the fiber.