Light guide protection structures for plasma system to disrupt vascular lesions

A catheter system for imparting pressure to induce fractures in a treatment site within or adjacent a vessel wall, comprising:

• a catheter that is configured to be advanced to the treatment site, the catheter comprising an elongate shaft, a balloon coupled to the elongate shaft, and a first light guide disposed along the elongate shaft, the elongate shaft defining a first recess within the balloon, the balloon being configured to be filled with a balloon fluid, the first light guide being configured to be positioned at least partially within the balloon and the balloon fluid, the first light guide including a first portion that is configured to extend into the first recess;
• and
• a first protection structure that contacts the first portion of the first light guide, the first protection structure being configured to provide structural protection to the first portion of the first light guide, the first protection structure including a potting material that at least partially fills the first recess, the potting material being optically matched to the first light guide.