Possibility of a distributed-feedback x-ray laser

It is suggested that distributed feedback might greatly improve the chances of achieving x-ray laser action in a crystalline material. We have considered the case where the cavity mirror structure is provided by internal Bragg scattering which is distributed throughout the lasing medium. In addition to providing efficient feedback, higher effective gains can be achieved by eliminating the influence of periodic absorbers which occur in selectively x-ray-pumped polyatomic crystals. This is accomplished by establishing a standing wave with its nulls on the periodically spaced absorbers.