Perspectives on Photocathode Lasers for Photo Injectors

Photocathode lasers are an extremely important component in modern photo injectors. In many cases they determine the beam quality of accelerators. Depending on the photocathode concept and the required electron beam properties, the photocathode laser must meet a wide range of requirements such as short pulses in the picosecond and sub-picosecond range with pulse energies up to the μJ level at wavelengths from green to UV, extremely high repetition rates up to 1.3 GHz for CW operation of accelerators, as well as single pulse and macro pulse operation with extreme demands on the pulse-to-pulse stability within these different pulse patterns. The available quantum efficiency and the required bunch charge ultimately determine the pulse energy requirement for the laser. A high repetition rate additionally creates the requirement for high average laser powers. Furthermore low emittance beams require transverse and longitudinal pulse shaping with high precision and flexibility. On the other hand, laser physics and technology have made great progress in the past few years. The aim of this workshop is to summarize the current state of the art of classical photocathode lasers and discuss the application of possible new technologies. In addition, possibilities and experiences of the industry for this area are to be discussed.