Papers by Keyword: Multi-Wavelength

Abstract: In this paper, we present the theoretical investigation of index-coupled distributed feedback (DFB) laser with tilted single mode ridge waveguides. By tilting part of the ridge waveguide in various degrees, DFB laser with manifold effective grating periods can be realized. The structure is analyzed using couple mode theory in matrix form based on threshold analysis. Important parameters of DFB laser like resonant frequency and threshold gains are obtained by solving the eigen-equation. The results indicate not only that the lasing frequency is modulated by the waveguide titling angle, but also large Gain Margin (GM) can be achieved at the threshold condition which enhance the stable single mode operation in index-coupled DFB laser.

Abstract: An instrumental method for measuring the properties of liquids has been developed. The instrument, called the fiber-capacitive drop analyzer (FCDA), is based on a specially designed drop sensor by means of the fiber drop analyzing technology and the capacitive drop analyzing technology, and produces a volume-based fiber drop trace (VFDT), which shows the relation between the light intensity passing through the liquid drop and the instant drop volume. Preliminary experiments have been carried out and these prove that VFDT externalizes the overall properties of tested liquids and is suitable for fine discrimination among different kinds of liquids. In this paper, a multi-wavelength drop analysis (MWDA) method is described. In this case, the light source of the FCDA is developed from a single wavelength to a multi-wavelength. A special filter is employed to sort out the signals from the mixed multi-wavelength signals and it becomes possible to get two or three VFDT with different light wavelength at the same time. As one knows, a material will absorb the light on certain wavelengths. It means that, for a mixed liquid, one can get different VFDTs by MWDA at the same time. By this way, the resolution capability of a FCDA is enhanced very much due to more information including in those VFDTs. A special signal process circuit, the key technology of the MWDA, is described in this paper. The test results show that the new circuit had satisfied the MWDA method well and will be very useful to an instrument of the FCDA with MWDA.