Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

The backward mode in an electromagnetically pumped free electron lasers

Abstract: A detailed analysis of the backward mode of an electromagnetic standing wave wiggler for FELs (free-electron lasers) is conducted. The analysis results in a clear understanding of the backward mode. It is indicated that the mode, for its absolute instability, should be suppressed in experiments for forward mode radiation to avoid beam disruption. On the other hand, it can be used as a self-excited high-power source with high efficiency in the low-frequency region and can saturate on a much higher level than the conventional forward mode. >

Planar lightwave circuit, including an optical branch circuit

Abstract: A planar lightwave circuit is provided which can be easily fabricated by an existing planar-lightwave-circuit fabrication process, which can lower the propagation loss of signal light and which can convert inputted signal light so as to derive desired signal light. A planar lightwave circuit having a core and a clad which are formed on a substrate, has input optical waveguide(s) (111) which inputs signal light, mode coupling part (112) for coupling a fundamental mode of the inputted signal light to a higher-order mode and/or a radiation mode, or mode re-coupling part (113) for re-coupling the higher-order mode and/or the radiation mode to the fundamental mode, and output optical waveguide(s) (114) which outputs signal light. The mode coupling part or the mode re-coupling part is an optical waveguide which has core width and/or height varied continuously.

Experimental study of a slot antenna excited by a TE011 mode coaxial cavity

Abstract: A slot antenna is developed to excite the high harmonic waveguide mode for generating large-area plasmas. This antenna consists of a TE011 mode coaxial cavity with the axial slots positioned on equal interval on the inner wall. The waves radiated from those slots can excite the high harmonic mode in the central area. With the azimuthal symmetric wave field of the TE011 mode, the number of the slots can be chosen to match the field pattern of the high harmonic mode. In this report, the dispersion relation of the coaxial waveguide, the coupling scheme and the mode competition of the cavity are studied. A method has been successfully developed to suppress the TE121 mode which is the most competing mode to the TE011 mode.

Mode Partition Noise In Nearly Single Mode Lasers With Multiple Side Modes

Abstract: The power penalty estimation for fiber optic communication due to mode partition noise in nearly single mode lasers is discussed. Nearly single mode lasers are modeled here as those with a single dominant mode and n side modes with significant strength. The dropout rate of each side mode obeys exponential distribution. The combined distribution of the dropout rate for n side modes is derived here. This distribution is combined with the statistically independent Gaussian receiver noise in estimating error probability and hence the power penalty. Calculations show that to ensure a 10 -12 error rate, the ratio of the main mode to the side modes must be greater than 57:1 for one side mode and greater than 67:1 for two side modes.

Circular to rectangular waveguide mode conversion through a parabolic cylinder waveguide–TEON incident

Abstract: The output mode of the gyrotron used as a high-power millimeter wave source for nuclear fusion plasma heating is the TEOn of a circular waveguide. It is desirable that this mode be converted to a linearly polarized mode such as the TEmO in a rectangular waveguide. This paper discusses mode conversion from a circular TEOn mode to rectangular waveguide modes in an oversized waveguide system in which a parabolic cylinder waveguide with its axis as a focal axis is inserted between the circular and rectangular waveguides. First, an approximate analysis is introduced based on the geometrical optics approximation by taking advantage of an oversized waveguide system. Subsequently, the mode matching method is used by expanding the fields into eigen-modes. The results for the optimum length of the parabolic cylinder waveguide obtained by the mode matching period agreed with those from the geometrical optics approximation. Hence, to a certain extent, an estimate based on the geometrical optics is effective in the oversized waveguide system. Since no accurate eigenvalues have been reported for the parabolic cylinder waveguide, the computed results are presented.