| The far infrared region of the electromagnetic spectrum, 15–3000 μm in wavelength, has a paucity of narrow band laser sources. To address the issue of whether a grating based free electron laser could operate well as such a source, a grating loaded waveguide of variable length, driven by a 2.3 MeV electron beam, was modeled, built, and tested, with the expectation of observing gain. Data was collected in the form of power spectra from a Fabry-Perot interferometer. Emission was observed for wavelengths between 0.30 mm and 3 mm, and there was very good agreement between the theoretical predictions for wavelength and the observed wavelengths. Gain was observed to agree with theoretical predictions to within a factor of 10 for wavelengths longer than 1 mm, but was between 10 and 100 times greater than predicted gain for shorter wavelengths. Overall emitted power agreed reasonably well with theoretical predictions, but observed power per wavelength was higher than predicted power for wavelengths shorter than 1.5 mm. |
