提出了波长为λi的入射激光与速度为v0、通过波长为λw周期磁场的电子束背散射产生波长λf激光的方案。只要v0足够大，就有λf远小于λi 。扭摆磁铁覆盖有缝隙的超导片后，λw虽不变，但有效背散射区纵向长度s能显著减小。足够强的入射激光也能使s显著减小。与电子束平行的激光谐振腔能产生强度足够大的入射激光。这样，波长λf激光就能实现。即使出射激光的光子数少于入射激光光子数，出射激光的功率仍可以大于入射激光的功率。

A scheme is investigated that laser with wavelength λf is produced by backscattering of incident laser with wavelength λi and an incident electron beam with its velocity v0 passing through a magnetic field with its period λw . The characteristics of the scheme are as follows. Provided that v0 is large enough, λi-λf.When superconductivity sheets with their gaps cover the waggle magnets, or when incident laser is strong enough, the longitudinal length of effective backscattering region s can markedly decrease. Thus, the laser with its wavelength λf can be realized. A laser resonator parallel with the incident electron beam can produce incident laser with high enough intensity. It is possible that the power of an outputting laser beam is larger than that of an incident laser beam, although the number of the photons of the outputting laser beam is less than that of the incident laser beam.