This research program will develop ultracompact laser instruments for the treatment of vitreo-retinal diseases. In particular, we will focus on researching specific medical needs, and the design and development of instruments that meet the specifications determined (i) for photosensitizer- based photodynamic therapy (PDT) of AMD/ARMD, and (ii) for surgical transections of epiretinal membranes. The various novel and unique fiber laser instruments to be developed here are based on extensive research experience on similar lasers by the team members, and contain diode pumps and rare-earth dopants as common key elements. Significant changes in the performance of the fiber lasers will be achieved by changing the diode pumps and rare-earth dopants (Er, Ho, Pr, Yb). One of the fiber lasers will be designed to emit at the absorption peak (630 nm) of benzoporphyrin derivate (BPD) while the fiber laser designed for surgical transections will emit at the 2.8-2.9 microm range corresponding to wavelengths where strong (acqueous) absorption occurs in epiretinal tissue. The breadboard version of the fiber lasers developed in Phase I will be used for preliminary tissue studies at the University of New Mexico Health Sciences Center, and knowledge acquired in this phase of the program will be utilized for the design and demonstration of laser instrument prototypes that will be used for live animal studies during Phase II. PROPOSED COMMERCIAL APPLICATION: Medical Applications: (i) Mid-IR lasers - compact, efficient and inexpensive replacement for Er:YAG and Er:YSSG lasers: applications include transmyocardial revascularization, tear duct and corneal surgery, dental plaque removal, and ear surgery, and (ii) Red lasers - photodynamic therapy for cancer treatment Non-Medical Applications: (i) Mid-IR lasers - Plastic welding, drilling of high precision micronsized holes in water-rich materials, and (ii) Red lasers - large-scale displays. data storage.