Design theory and experimental investigation of the low frequency and high power rare earth magnetostrictive flextensional transducer (Ⅰ). Theoretical part

The energy relationships among all the elements, by which the magnetostrictive transducers are manufactured, in Finite Element Method (FEM) are analyzed, then the expres- sions of FEM dynamics equations and performances formulas for magnetostrictive transducers are derived. The vibrating modes of the class VII transducer and its shell vibration are calcu- lated theoretically and the results point out that there is a breathing mode and if the transducer works at this mode, the transducer will vibrate with a greater volume speed and source level.

Investigation of ellipticity and pump power in a passively mode-locked fiber laser using the nonlinear polarization rotation technique

An elliptical initial polarization state is essential for generating mode-locked pulses using the nonlinear polarization rotation technique. In this work, the relationship between the ellipticity ranges capable of maintaining mode-locked operation against different pump power levels is investigated. An increasing pump power, in conjunction with minor adjustments to the polarization controller＇s quarter waveplate, results in a wider ellipticity range that can accommodate mode-locked operation. Other parameters such as noise, pulsewidth, and average output power are also observed to vary as the ellipticity changes.

Design theory and experimental investigation of the low frequency and high power rare earth magnetostrictive flextensional transducer (Ⅱ). Experimental part

Vibrating modes of the manufactured flextensional transducer and its shell are experimentally investigated. The result are consistent with the theoretical calculations. The acoustical performances for the transducer are measured: resonance frequency is 1.16 kHz in the underwater, bandwidth is 680 Hz, mechanical quality factor is 1.71, transmitting current response is 186.1 dB, electromechanical efficiency is 13.1%.