Luo Fubin, Yang Zining, Zhao Huizi, Jiang Longfei, Sun Janyong, Liu Qinshan, Wang Rui, Yang Weiqiang, Wang Hongyan, Xu Xiaojun
Opt Express. 2025 Jun 30;33(13):28832-28840. doi: 10.1364/OE.566505.
Diode-pumped alkali lasers (DPALs) are promising candidates for high-energy lasers. Traditionally, the volume Bragg grating coupled diode lasers were used as pumping sources with a spectral linewidth of ∼100 pm (FWHM). To match the pump spectrum, buffer gases such as helium at atmospheric pressure are typically employed to broaden the alkali atomic absorption line. In this study, we conducted an ultra-narrow diode laser with pm-level linewidth and used it as the pumping source to demonstrate a low-pressure rubidium vapor amplifier. By inserting an Rb Faraday anomalous dispersion optical filter (FADOF) into the external cavity, the wavelength of the diode laser was strictly locked to the Rb D line (∼780.25 nm), and the linewidth was narrowed from 1.7 nm to 3.9 pm (1.9 GHz). Using this pumping source, effective amplification was achieved even at a CH pressure as low as 50 Torr. At 200 Torr CH pressure, the system attained an amplification factor of ∼344 with a large gain coefficient of 2.9 cm, comparable to the amplification factor of 348 obtained at 400 Torr CH. The low-pressure DPALs pumped by pm-level ultra-narrow diode lasers offer advantages such as low pump threshold, high optical conversion efficiency, and good beam quality, which has potential for power scaling applications.
二极管泵浦碱金属激光器（DPALs）是高能激光器的有前途的候选者。传统上，体积布拉格光栅耦合二极管激光器被用作泵浦源，其谱线宽度约为100 pm（半高宽）。为了匹配泵浦光谱，通常采用诸如大气压下的氦气等缓冲气体来展宽碱金属原子吸收线。在本研究中，我们研制了一种线宽为皮米级的超窄二极管激光器，并将其用作泵浦源来演示低压铷蒸汽放大器。通过在外腔中插入一个Rb法拉第反常色散光学滤波器（FADOF），二极管激光器的波长被严格锁定到Rb D线（约780.25 nm），线宽从1.7 nm窄化到3.9 pm（1.9 GHz）。使用这种泵浦源，即使在低至50 Torr的CH压力下也能实现有效放大。在200 Torr的CH压力下，该系统获得了约344的放大倍数，增益系数高达2.9 cm，与在400 Torr CH下获得的348的放大倍数相当。由皮米级超窄二极管激光器泵浦的低压DPALs具有泵浦阈值低、光转换效率高和光束质量好等优点，在功率放大应用方面具有潜力。
