Two kinds of tunable coherent photons for positronium formation and annihilation can be generated by coalescing focused, high-intensity e and e+ beams which are accelerated in the same direction. Positronium formation can be enhanced by laser irradiation or by installing an undulator magnetic field in cases where the density of e and e+ plasma is not high. In the case of very high density, slender rod-type geometry plasma, positronium can be formed by super-radiant, superfluorescence, or amplified, spontaneous emission processes, and a coherent laser can be generated.