Absfracf-The high-harmonic gyro-traveling wave tube (gyro-TWT) is a high-power ( 2 1 kW) millimeter wave amplifier based on the synchronous interaction of a beam of lafge-orbit axis-encircling electrons with a high-order cylindrical waveguide mode. Since the interaction occurs at a high harmonic of the cyclotron frequency, the intense magnetic fields required for the conventional fundamental-mo...

An electron cyclotron resonance plasma produced in a cylindrical waveguide with external permanent magnets was investigated as a possible plasma cathode electron source. The configuration is desirable in that it eliminates the need for a physical antenna inserted into the plasma, the erosion of which limits operating lifetime. Plasma bulk density was found to be overdense in the source. Extract...

The design, fabrication and spectroscopic characterization of ytterbium-doped Ta2O5 rib waveguide are described. The waveguides are fabricated on silicon substrates and operate in a single mode at wavelengths above 970 nm. The peak absorption cross-section was measured to be 2.75 × 10 cm at 975 nm. The emission spectrum was found to have a broad fluorescence spanning from 990 nm to 1090 nm with...

We present the self-aligned fabrication of on-chip devices in which waveguides, incorporating integrated photoconductive switches, are combined with two-dimensional electron systems to allow probing of the ultrafast (terahertz frequency range) properties of confined semiconductor systems, both at cryogenic temperatures and in high magnetic fields. We demonstrate the direct injection of on-chip ...

1098-4402= A Bragg waveguide consisting of multiple dielectric layers with alternating index of refraction becomes an excellent option to form electron accelerating structure powered by high power laser sources. It provides confinement of a synchronous speed-of-light mode with extremely low loss. However, laser field cannot be coupled into the structure collinearly with the electron beam. There...

Solid state lasers have achieved high energy output with very short pulses (several Joules with pulses shorter than 1ps, peak power in the order of terawatts)[1]-[5]. Lithography and micro machining enables fabrication of features much less than 1μ m[13]-[17]. Combined with the fact that material damage threshold increases with shorter pulses[20][21], it is now possible to achieve electric fiel...

We present details of the homo-epitaxial growth of Yb:YAG onto a <100> oriented YAG substrate by pulsed laser deposition. Material characterization and initial laser experiments are also reported, including the demonstration of laser action from the 15 μm-thick planar waveguide generating 11.5 W of output power with a slope efficiency of 48%. This work indicates that under appropriate condition...

A metallic coupler is proposed to interface a silicon on insulator (SOI) waveguide with a narrow hybrid plasmonic waveguide (200× 200 nm). The device operation is investigated and optimized to attain the best tradeoff between the mode confinement and the propagation loss. Calculations reveal that a high confinement and low loss of the energy is achieved from a silicon slab waveguide into the di...

Abstract The HE 11 hybrid mode, propagating in an overmoded corrugated circular waveguide, is widely used for low loss transmission of high-power microwaves. Due to the inherent broadband frequency behaviour, this will be also essential future radar applications, like space debris observation earth orbit (LEO). A promising amplifier concept such sensors a helical gyro-TWT. However, since mode n...

There is a great deal of interests and efforts in the area of femtosecond (fs) laser direct writing of transparent materials, which shows promise to be a powerful and flexible technique for rapid fabrication of photonic micro-device, such as gratings, waveguides and optical amplifiers. Waveguide properties depend critically on the sample material properties and writing laser characteristics. In...