a first light guide and a second light guide that are each configured to selectively receive light energy from the light source;

a multiplexer that receives the light energy from the light source in the form of a source beam and selectively directs the light energy from the light source in the form of individual guide beams to each of the first light guide and the second light guide, the multiplexer including (i) a multiplexer base that is fixed in position relative to the first light guide and the second light guide, (ii) a multiplexer stage that is movably supported on the multiplexer base, (iii) a stage mover that is configured to move the multiplexer stage in a single linear degree of freedom relative to the multiplexer base, (iv) a redirector that is mounted on the multiplexer stage, and (v) coupling optics that are mounted on the multiplexer stage;

a catheter shaft;

a balloon that is coupled to the catheter shaft, the balloon including a balloon wall that defines a balloon interior, the balloon being configured to retain a balloon fluid within the balloon interior, the balloon being selectively inflatable with the balloon fluid to expand to an inflated state such that when the balloon is in the inflated state the balloon wall is configured to be positioned adjacent to the treatment site, the first light guide and the second light guide being positioned at least partially within the balloon interior; and

a system controller including a processor that is configured to control operation of the light source to generate a single source beam in the form of pulses of light energy that are directed to the multiplexer;

wherein the source beam being directed toward the multiplexer initially impinges on the redirector, the redirector being configured to redirect the source beam toward the coupling optics, the coupling optics being configured to focus the individual guide beams received from the redirector to each of the first light guide and the second light guide;

wherein movement of the multiplexer stage relative to the multiplexer base results in corresponding movement of the redirector and the coupling optics relative to the first light guide and the second light guide;

wherein the stage mover moves the multiplexer stage to align a first beam path of a first guide beam with the first light guide before the system controller fires the light source to generate the first guide beam that is directed to the first light guide;

wherein the stage mover subsequently moves the multiplexer stage to align a second beam path of a second guide beam with the second light guide before the system controller fires the light source to generate the second guide beam that is directed to the second light guide; and

wherein the first light guide and the second light guide receive the light energy from the light source and guide the light energy from the light source into the balloon interior to generate plasma in the balloon fluid within the balloon interior, the plasma generation causing rapid bubble formation and imparting pressure waves upon the balloon wall adjacent to the treatment site.