This paper will first discuss characteristics of the different laser sources with particular emphasis on the display output power needs. There are a number of nonlinear optical effects that appear useful to display systems; of particular interest for displays are the effects related to the controllable change of the wavelength of coherent radiation incident on the nonlinear media. The nonlinear techniques to be discussed are those related to harmonic generation, Raman laser action, and optical parametric amplification and oscillation. Calculations on the parametric oscillation effect show that a one watt blue or UV laser can effectively provide the optical pumping which would result in a very appreciable tunable optical output over the visible spectrum.