Characterization and Compensation of the Residual Chirp in a Mach-Zehnder-Type Electro-Optical Intensity Modulator

We utilize various techniques to characterize the residual phase modulation of a fiber-based Mach-Zehnder electro-optical intensity modulator. A heterodyne technique is used to directly measure the phase change due to a given change in intensity, thereby determining the chirp parameter of the device. This chirp parameter is also measured by examining the ratio of sidebands for sinusoidal amplitude modulation. Finally, the frequency chirp caused by an intensity pulse on the nanosecond time scale is measured via the heterodyne signal. We show that this chirp can be largely compensated with a separate phase modulator. The various measurements of the chirp parameter are in reasonable agreement.Comment: 11 pages, 6 figure

Some new results on the mechanism of boiling

The paper presents a selection of results found in the authors' laboratories during recent years. Some of these results are partly published elsewhere, others not. First a model of heat transfer to single bubbles is presented which includes the governing physical mechanisms of this process. Then an experimental technique suitable for precise and systematic measurements of entire boiling curves under steady-state and transient conditions is described. Based on this technique studies on the mechanisms of boiling utilizing microoptical probes and microthermocouples are carried out for all boiling regimes between fully developed nucleate boiling and film boiling. The results are discussed and conclusions are drawn on further research requirements. (orig.)Available from TIB Hannover: RR 8872(1998,26) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman