Ellipsoidal diffraction grating as output coupler for quasi-optical gyrotrons
The use of a diffraction grating arranged in the -1 Littrow mount as an output coupler for a quasi-optical Fabry-Pérot resonator at microwave frequencies (100 GHz) was suggested in 1990. A planar grating with curvilinear grooves (in order to match the Littrow condition everywhere on the surface for a given Gaussian beam) gives a power coupling efficiency of 85%, which is limited by the depolarisation induced by the curvature of the grooves. An ellipsoidal grating with linear, equidistant grooves minimises the depolarisation but gives approximately the same global efficiency because of distortion. Low power tests on an improvement of the second scheme are reported, based on curved grooves on an ellipsoidal surface, which gives a global efficiency of 94%.
Bibliographic Reference: Paper presented: 16th International Conference on Infrared and Millimeter Waves, Lausanne (CH), Aug. 26-30, 1991
Availability: Available from (1) as Paper EN 36309 ORA
Record Number: 199111112 / Last updated on: 1994-12-02
Original language: en
Available languages: en