Optical fiber acoustic sensing multiplexing system based on TDM/SFDM

We propose a system of time-division multiplexing(TDM) and spatial frequency-division multiplexing(SFDM). Extrinsic Fabry–Perot interferometric sensors are applied to detect weak acoustic signals. The broadband source is employed, the light from it is modulated by a pulse signal sequence and is efficiently amplified by semiconductor optical amplifiers. Experimental results show that the equivalent noise pressure spectrum level is-97.2 d B re 1 rad/√Hz below 1250 Hz, and the cross talk between two sensors in one TDM channel is-32.7 d B with a cavity length difference of 60 μm. The number of sensors in this multiplexing system can theoretically reach 160.     

进出口方式对微小通道热沉性能的影响

搭建微小通道热沉系统实验台,分别测试了单进单出和两进两出方式的微小通道热沉的流动与传热特性。结果表明,在相同体积流量和微小通道热沉结构的条件下,单进单出热沉的传热系数高于两进两出热沉,而压降低于后者。在相同耗功下,单进单出热沉的传热系数明显高于两进两出热沉。同时,单进单出热沉均温性优于两进两出热沉。故热沉进出口采用单进单出的方式性能更优。