Absorber for terahertz radiation management

摘要

A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

主权项

1. A method for minimizing the power degradation of a terahertz (THz) beam in a free electron laser (FEL) having a beam tube, comprising:
a. providing a THz absorber ring having an upstream side, a downstream side, and a plurality of wedges spaced radially around the upstream side of the absorber ring; b. placing said THz absorber ring within said beam tube with the upstream side of said THz absorber ring facing the oncoming THz beam; and c. absorbing irregular THz radiation to minimize the power degradation of the THz beam.