Far-infrared tunable radiation is produced in a four-level laser system by using a pumping means for exciting population from the lowest level of the system to the upper level of a laser transition to create a population inversion between the upper and lower levels of the laser transition and a laser beam which is nearly resonant with the lower level of the laser transition and a fourth level of the system. The laser beam shifts the lower level of the laser transition according to the dynamic Stark effect to provide for tuning of the far-infrared radiation.
A system and method are disclosed for adjusting the gain profile of an optical amplifier including a pump laser and an active gain element by selectively controlling the electron populations of at least one Stark sublevel of the electronic energy levels of the optical amplifier's active gain element. By dynamically controlling the electron populations of selected Stark sublevels the gain profile of the active gain element can be flattened. In a first method for controlling electron populations two-photon transitions are initiated between a pair of Stark sublevels of the same energy manifold of the active gain element. Two-photon transitions are stimulated by two additional pump lasers operating at wavelengths whose difference approximates the energy difference in the pair of Stark sublevels between which electrons are to be moved. In a second method for controlling electron populations single-photon transitions are initiated between a pair of Stark sublevels of different energy manifolds of the active gain element. Single-photon transitions are stimulated by an additional pump laser operating at a frequency difference that approximates the difference in the pair of energy levels. Alternatively, single photon transitions are stimulated by operating the amplifier's pump laser at a wavelength selected so as to simultaneously cause electron transitions from the ground level of the active gain element to one of the higher energy levels and electron transitions from a selected Stark sublevel of the upper laser level to a yet higher energy level.
A method is disclosed for irradiating a biological sample with far infrared (FIR) irradiation, including providing tunable FIR irradiation, removing X rays from the irradiation, and irradiating at least one biological sample with the tunable FIR irradiation, wherein at least a component of the biological sample undergoes at least one of a conformational change or a phase change in response to the irradiating. An FIR irradiation device is disclosed, including an FIR source producing an FIR irradiation having a tunable wavelength, the source being capable of continuous-wave output, and a filter receiving the irradiation from the source.
The present disclosure is directed to laser apparatuses for generating coherent electromagnetic laser radiation having an electron beam generator, a diffraction grating element oriented such that a beam of electrons from the electron beam generator is directed over the diffraction grating element, and at least one wing element coupled to the diffraction grating element. In some embodiments, the wing element(s) can be coupled to a top portion of the diffraction grating element. While in others, the wing element(s) can be coupled to a side portion of the diffraction grating element. The present disclosure is also directed to methods of manufacturing diffraction grating elements involving placing at least one secondary conducting sheet having a first height on at least one primary conductive sheet having a different second height, and securing the primary and secondary conductive sheets together. The primary and secondary conductive sheets can be alternating and their thicknesses may also be different. Additionally, the primary and secondary conductive sheets may be secured via a clamping device.
