Photocathodes are critical for generation of high-brightness electron beams in accelerators that are used in science, industry, and medical disciplines. A visible wavelength-tunable picoseconds laser is required to support optimization of photocathodes leading to more compact, high-performance, and cost-effective systems. Such lasers are not available commercially. With new sources of high-brightness electron beams affordable for universities, commercial laboratories (e.g., semiconductor material development), and hospitals, the US would be able to maintain its technological leadership. In the proposed Phase I, we will experimentally validate and characterize the performance of Aqwestâs concept, anchor our predictive models, validate future scaling, and use these results to design a Phase II prototype driver. Means for pulse selection and synchronization will be evaluated. We will also generate plans for Phase II and eventual commercialization. In Phase II, we plan to develop and demonstrate a photocathode drive laser meeting the DOE functional requirements. Commercialization plans will be further refined and put into effect. Our innovative architecture enabled by the advent of SC lasers offers a direct path to the development and early deployment of visible wavelength- tunable photocathode drivers. The tunable laser developed by this project will also become an important tool for a broad range of applications. For example, in laser material processing such as cutting, welding, surface treatment, 3D printing, a tunable high-average power laser offers a new capability to precisely tune into specific absorption features of the workpiece. This new capability promises to revolutionize the field and possibly create new industry segments. A tunable blue-to-red laser is also needed for medical imaging and photodynamic therapy for cancer. A tunable laser scanning through the spectrum is desired as an illuminator for active hyper-spectral imaging for long-standoff remote sensing especially for ecological, environmental, agricultural, and industrial purposes