Chodzko R A
Appl Opt. 1974 Oct 1;13(10):2321-5. doi: 10.1364/AO.13.002321.
A new type of unstable resonator has been developed that permits multiple-selected-line operation. Selected-line operation is obtained with a diffraction grating that is oriented at an angle that is different from the Littrow angle. Secondary feedback mirrors at the appropriate angles provide an independent threeelement cavity for each wavelength selected. The off-Littrow configuration is less efficient than a singleline cavity at the Littrow angle because there are secondary zero-order beams at each wavelength as well as a primary zero-order beam at all selected wavelengths. In the limit of a high gain this loss in efficiency is shown to be significantly reduced. Two types of multiple-selected-line unstable resonators are considered: an edge-coupled design, which produces an annular beam with a 45 degrees output coupling mirror, and a continuously coupled design, which uses the primary zero-order beam as output. Experiments have been carried out with a multiple-selected-line unstable resonator on a cw HF laser. Selected-line operation was obtained on the P(2) (5) and P(1) (6) HF transitions in a continuously coupled design.
已经开发出一种新型的不稳定谐振器，它允许进行多谱线选择操作。通过一个与利特罗角成不同角度取向的衍射光栅来实现谱线选择操作。以适当角度设置的二次反馈镜为每个选定波长提供一个独立的三元件腔。非利特罗配置在效率上比处于利特罗角的单谱线腔要低，因为在每个波长处都有二次零级光束，并且在所有选定波长处都有一个初级零级光束。在高增益极限情况下，这种效率损失被证明会显著降低。考虑了两种类型的多谱线选择不稳定谐振器：一种是边缘耦合设计，它通过一个45度输出耦合镜产生环形光束；另一种是连续耦合设计，它将初级零级光束用作输出。已经在连续波HF激光器上使用多谱线选择不稳定谐振器进行了实验。在连续耦合设计中，在P(2)(5)和P(1)(6) HF跃迁上实现了谱线选择操作。
