Lasing Without Inversion in He and He-like Ions in XUV and X-Ray Regions

这个项目是为了演示在极真空紫外线(XUV)和X射线区域的无反转激光(LWI)。该项目的基础是最近发展起来的在58 nm的He原子和6.1 nm的三重电离B的类He离子中的LWI理论，作为三能级系统中的瞬时激光。LW I的重要特征是XUV和X射线的相干控制，激光波长随着Z的增加而迅速减小，这种激光与Dicke超辐射有共同的特点，因此可以产生强的XUV和X射线激光。原子和辐射物理中的量子相干现象导致了许多有趣和意想不到的结果。例如，在相干叠加态中制备的原子系综将产生自感透明、光子回波和相干拉曼拍子。通过在相干叠加态中制备原子系统，在一定条件下，原子的相干性可以抵消吸收，但不能抵消发射，这是LWI的基础。这通常是在三能级或四能级原子系统中完成的，在这些系统中，存在可能破坏性干扰的相干吸收路径，从而导致吸收的取消。在系统的激发态下的少量布居可以导致净增益。以前的LWI研究主要局限于光谱的可见光和红外区。这是第一次尝试通过激光重振在XUV和X射线区域产生激光，这两个区域很难产生。实现XUV的LWI并将其进一步扩展到X射线区域，将为需要便携式、廉价的相干XUV和X射线设备的研究人员提供一个极好的工具。这项研究将为研究生和非常高级的本科生的教学和培训提供一个极好的机会。我们以前的几名研究生已经是在激光和等离子体基本理论、实验、激光和等离子体物理应用以及实验和激光应用的计算机模拟领域的有成就的科学家和行政领导。

This project is to demonstrate Lasing Without Inversion (LWI) in extreme vacuum ultraviolet (XUV) and X-ray regions. The basis for the project is the recently developed theory of LWI in He atoms at 58 nm and in He-like ions of triply ionized B at 6.1 nm, as transient lasing in a three-level system. The important features of LWI are the coherent control in the XUV and X-ray, and that lasing wavelengths rapidly decrease with increasing Z. Such lasing has common features with Dicke super-radiance, and, hence, can yield strong XUV and X-ray lasing. The quantum coherence phenomenon in atomic and radiation physics has led to many interesting and unexpected consequences. For example, an atomic ensemble prepared in a coherent superposition of states will yield self-induced transparency, photon echo, and coherent Raman beats. By preparing an atomic system in a coherent superposition of states, under certain conditions it is possible for atomic coherence to cancel absorption but not emission, which is the basis for LWI. Frequently, this is accomplished in three- or four-level atomic systems in which there are coherent routes for absorption that can destructively interfere, thus leading to the cancellation of absorption. A small population in the excited state of the system can lead to net gain. Previous LWI studies have been limited primarily to the visible and infrared regions of the spectrum. This is the fist attempt to produce lasing in the XUV and X-ray regions, which are difficult to generate, via LWI. Achieving the proposed LWI for XUV and farther extending it to the X-ray region would provide an excellent "tool" for researchers who need portable, inexpensive coherent XUV and X-ray devices.Ths research will provide an excellent opportunity for teaching and training of graduate students, and also for very advanced undergraduate students. Several of our former graduate students are already accomplished scientists and administrative leaders in the areas of basic laser and plasma theory, experiments, applications of lasers and plasma physics, as well as in computer simulations of experiments and laser applications.