Kazue Otsuka

Measuring the longitudinal distribution of four-wave mixing efficiency in dispersion-shifted fibers

We measured and analysed four-wave mixing (FWM) efficiency and fluctuation along the actual dispersion-shifted fibers (DSFs). In the short, 1.1-km DSF, our results agreed with theory, and we also obtained zero-dispersion wavelength /spl lambda//sub 0/, zero-dispersion slope dD/d/spl lambda/, and nonlinear refractive index n/sub 2/ simultaneously. In the long, 23-km, DSF, a high FWM efficiency was observed in the wide wavelength region, due to the longitudinal zero-dispersion wavelength distribution. The fluctuation range was about 3.5 nm and the maximum slope about 1.1 km/nm.<<ETX>>

Electron Linear Accelerator Using Phased Multi-Electromagnetic-Wave Beams

The motion of charged particles in a multi-electromagnetic-wave beam (multi-EM beam) system has been investigated numerically. This system consists of many plane electromagnetic-wave beams propagating parallel to each other, but the phase is delayed successively from one beam to the next. The resultant electromagnetic field seems to be a slow wave which can interact with the particle beam. When a static magnetic field is applied parallel to the fluctuating magnetic field of the wave, it is concluded from numerical calculations that the charged particles injected in this scheme are trapped in the apparent wave and accelerated stably to high energy, close to the speed of light.

Electron Linear Accelerator Based on the Crossed-Wave Electric and Static Magnetic Field

A new type of linear electron accelerator, based on the crossed-wave-electric field and static magnetic field system known as the vp×B acceleration mechanism observed originally in plasma, has been demonstrated in vacuum for the first time. In this scheme a static magnetic field is applied vertically to direction of the wave propagation and the particles are accelerated along the wavefront in a constant phase with respect to the wave. The present machine can be either a conventional linear accelerator or a new type of vp×B accelerator without any modification. An energy gain of 12.8 keV for electrons is observed from an incident energy of 66 keV in a 0.5 m accelerator, when an external magnetic field of 2.5 G is applied. The energy gain is 30% higher than that of conventional linacs. The energy gain is proportional to the square of the applied magnetic field strength B0

Optical communication system which determines the spectrum of a wavelength division multiplexed signal and performs various processes in accordance with the determined spectrum

as long as the electrons are trapped within a wave trough. Experiments have been carried out with two different RF power levels in order to confirm the trapping condition for electrons, which depends on both the electric field and the applied magnetic field. The results of experiments and theories are in fairly good agreement.