We propose and demonstrate the use of laser intensity modulation for the multiplexing and demultiplexing of fiber Bragg grating-based ultrasound sensors. The method utilizes an intensity modulator to modulate the output power of the laser with a frequency much higher than that of the ultrasounds. The high-frequency-modulated optical signal serves as a carrier signal. Ultrasonic signals impinged onto the sensor appear as the envelope of the carrier signal. In the frequency domain, the carrier signal and the sidebands encoded with the ultrasonic signal are separated from those of other channels and, thus, can be isolated using an electronic bandpass filter for crosstalk-free ultrasound detection. Each laser can be tuned to demodulate any sensor covered by the wavelength range of the laser, and a common photodetector is used for all channels. Both a theoretical analysis and experimental verification are provided to demonstrate the concept.

中文翻译：

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使用激光强度调制的多路复用光纤超声传感器

我们提出并演示了基于激光强度调制的光纤布拉格光栅超声传感器的复用和解复用。该方法利用强度调制器以远高于超声的频率调制激光器的输出功率。高频调制的光信号用作载波信号。撞击到传感器上的超声波信号显示为载波信号的包络线。在频域中，用超声信号编码的载波信号和边带与其他通道的那些分离，因此可以使用电子带通滤波器进行隔离，以进行无串扰的超声检测。可以对每个激光器进行调谐，以解调激光器波长范围所覆盖的任何传感器，并且所有通道均使用通用的光电检测器。