Wavelength Tunable Visible Picosecond Laser

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 Phase I, we constructed a proof-of-principle demonstrator system and experimentally validated our concept. We demonstrated key parameters targeted by the DOE including continuous wavelength tunability from 484 to 643 nm, pulse energy up to 425 µJ, and output bandwidth of 1 nm. In Phase II, we started developing and characterizing a full-scale Prototype WTVPL targeting the DOE functional requirements. We have fabricated >85% of the Prototype hardware, completed and started activation of the source laser, completed an initial control system for pulse timing and wavelength tuning, and started system activation with 20 ps pulses. In Phase IIA, we will complete the originally planned initial Phase II prototype WTVPL. In particular, we will: 1) Robustize the optics to handle full pulse energy; 2) Robustize the thermal management for continuous operation at high-average power; 3) Develop and validate temporal pulse shaping; and 4) Enhance the computer controls for sub- picosecond level synchronization with the RF wave, 5) Implement the wavelength stabilization, and 6) Conduct systematic validation testing over the entire operating envelope. The resulting laser system will be a full-scale prototype offering a direct path to a photocathode drive laser deliverable in Phase III. Commercial applications for a tunable high-average power laser based on the Aqwest concept include science, remote environmental sensing (illuminator for active hyperspectral imaging), and industrial laser material processing.