Photonically controlled ultrasonic arrays: scenarios and systems

Wavelength diversity coupled with fiber-based time delay, optical energy delivery, and ultrasonic energy generation and sensing, are proposed for the first time to form a novel, rapidly tunable (e.g., 1 kHz-100 MHz) and wide instantaneous bandwidth (e.g., >50 % bandwidth at center carrier), ultrasonic probe system. This novel photonic system can be used for a wide variety of ultrasonic applications such as therapy, diagnostics, and non-invasive surgery, particularly for intracavity operation with a typical 100 channel/transducer element count. This ultrasonic system architecture relies on a novel multi-wavelength optical delay line module using two high speed (i.e., <10 microseconds wavelength switching time), bulk acousto-optic tunable filters, that provide collinear, high power, multi-wavelength optical input and output beams. This wavelength selection module also provides high optical throughput (e.g., 85% efficiency), and excellent, e.g., <-30 dB optical or <-60 dB electrical blockage of the unwanted leakage (undiffracted) light, preventing noise propagation when such modules are cascaded to provide switched signal time delays.