百瓦级1.2/1.5μm双波长金刚石拉曼激光器(特邀)

Hundred-watt dual-wavelength diamond Raman laser at 1.2/1.5 μm(Invited)

具有高功率、高光束质量的双波长激光器在精密光谱、共振干涉测量和激光雷达等领域有着重要的应用。但是受到激光工作物质固有的光谱和增益特性制约,通过传统的粒子数反转激光器难以直接获得高功率的双波长激光输出,因此通常需要结合非线性光学频率变换技术将常规的单一波长高功率激光拓展至一个或若干个特殊波段。受激拉曼散射作为一种三阶非线性效应,具有频移大、自相位匹配和光束净化等优点,是实现高效率、高光束质量波长转换有效手段。利用具有宽光谱透过范围(>0.23μm)、超高热导率(>2 000 W·m^(-1)·K^(-1))和大拉曼频移(1 332 cm^(-1))等优异特性的金刚石晶体作为拉曼增益介质,通过外腔振荡结构实现了1μm泵浦光直接向1.2μm和1.5μm双波长激光的高效转换,在最高稳态泵浦功率414 W的条件下获得了1.2μm和1.5μm功率分别为72 W和110 W的输出。该研究为实现高功率的双波长激光输出开辟了新的途径。

Dual-wavelength lasers with high power and high beam quality are critical to the applications such as precision spectroscopy, resonant interferometry, lidar, etc. However, limited by the intrinsic spectral and gain characteristics of currently available laser gain materials, it is difficult to realize high-power dual wavelength lasing directly from inversion lasers. To overcome this problem, nonlinear optical frequency conversion has been applied to convert the high-power laser in a conventional band to another or several hard-to-reach bands. As a third-order nonlinear effect, stimulated Raman scattering has advantages including large frequency shift, selfphase matching, and beam clean-up effect that lead to Raman laser an effective means to achieve high efficiency and high beam quality wavelength conversion. In this paper, diamond crystal that with a wide spectral transmission range(>0.23 μm), ultra-high thermal conductivity(>2 000 W·m^(-1)·K^(-1)) and large Raman frequency shift(1 332 cm^(-1)) was used as the Raman gain medium. By using a 1 μm laser as pump source, dual-wavelength lasing at 1.2 and 1.5 μm was achieved based on an external cavity Raman oscillator. With a maximum steadystate pump power of 414 W, output powers up to 72 W at 1.2 μm and 110 W at 1.5 μm were obtained. This study has opened a new way to realize high-power dual-wavelength laser output.