In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules, such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved at higher temperature.
In this work, Bi2Fe4O9superfine particles were prepared by hydrothermal method and effects of hydrothermal conditions on the microstructure of Bi2Fe4O9, especially the concentration of OH-([OH-]) in initial solutions, were investigated. The results showed that [OH-] had obvious influences on the growth of Bi2Fe4O9under the same hydrothermal temperature and hydrothermal time. Phase structure of Bi2Fe4O9unchanged with the increase of [OH-] and maintained orthorhombic structure. Besides, the microstructure of Bi2Fe4O9was carefully studied through transmission electron microscopy (TEM). The results suggested that the mechanism of Bi2Fe4O9growth was Ostwald ripening. In conclusion, Bi2Fe4O9superfine particles with good morphology and microstructure can be successfully synthesized when the concentration of OH-is 2 mol/L and hydrothermal conditions are 240 °C for 6h.Keywords: Bi2Fe4O9, hydrothermal method, phase structure, growth mechanism Topic code numbers: C2
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