Measurements of pulse mode behavior in weakly-clad silica waveguides

The behavior of 30 MHz pulses in eight weakly-clad (acoustically) silica fibers was examined with the goal of developing catheters for intravascular ultrasonic imaging. Comparisons of pulses prior to entering and after exiting the waveguide (single pass) were made to assess the fibers ability to propagate high frequency sound. An immersion transducer focussed sound into the proximal ends of 500 micron diameter silica fibers and a high frequency hydrophone was used to measure the ultrasound signal arriving at the distal ends. Attenuation and dispersion were found to be too large for imaging purposes.