We report evidence of strong lasing on the 4p-4s transition at 62.7 nm in nickel-like krypton occurring simultaneously with the usual 4d-4p lasing at 32.8 nm. The gain dynamics of both transitions were experimentally and numerically investigated and found comparable. The two-color amplifier was seeded by the same harmonic pulse, therefore producing a short-duration coherent two-color soft x-ray laser pulse. Both transitions offer similar prospects of pulse energy and duration and could lead to the delivery of intense and ultrashort two-color coherent soft x-ray pulses with a controllable delay.

中文翻译：

---

高密度镍状K等离子体中的两色软X射线激光发射。

我们报告了在镍样k中62.7 nm处的4p-4s跃迁发生强激光的证据，同时在32.8 nm处发生了通常的4d-4p激射。对两个跃迁的增益动力学进行了实验和数值研究，发现具有可比性。双色放大器由相同的谐波脉冲播种，因此产生了短时相干的双色软X射线激光脉冲。两种跃迁都提供了类似的脉冲能量和持续时间前景，并且可能导致以可控制的延迟传递强和超短的两色相干软X射线脉冲。