Abstract: Methods and apparatus for providing signal modulation or control of collector initialized and sustained field emission in field emitter devices without input circuit loading. A special control gate is used to modulate emission with no resultant steady-state emitter-gate current, thus increasing input resistance. The control gate may be well spaced from the emitter tip and the collector because it is not used to initiate and sustain emission from the emitter. This lowers emitter-gate and collector gate capacitances, thereby increasing input reactance for high frequency input signals. The collector-sustained field emission provides a low output resistance with relatively great collector-emitter spacing to provide high output reactance so that the high frequency response is extended.

Abstract: An optical fiber for amplifying or sourcing a light signal in a single transverse mode. The fiber comprises a host glass doped with erbium (Er) and a sensitizer such as ytterbium (Yb) or iron (Fe). Preferably the host glass is doped silicic glass (e.g., phosphate or borate doped). Electrical energy is provided to diode lasers that pump the Nd laser rod, which in turn pumps the fiber. Such a configuration for pumping the fiber provides a high energy transfer from the diodes to the Nd laser rod, which in turn enables high pumping powers to be coupled into the single-mode co-doped fiber. Based on the amplification characteristics of the co-doped fiber and the efficient coupling of power from the laser diodes, the amplifier provides power and small signal gains comparable to the best observed, while requiring only conventional and readily available diode-based pump sources.