Single-longitudinal-mode diamond Raman lasers in the near-infrared spectral region

Lasers operating in single-longitudinal-mode (SLM) are of great importance for high-precision measurements in nonlinear optics and spectroscopy as well as for applications in remote sensing, laser cooling and the flourishing field of gravitational wave detection. However, stable SLM in standing-wave inversion lasers is impeded by spatial hole burning which causes mode instability and can only be overcome at the expense of power limitations and/or higher complexity of the laser system, e.g. by means of injection-seeding, ring or microchip laser designs. As an alternative approach, we demonstrate that the nonlinear optical process of stimulated Raman scattering provides a spatial hole burning free gain which enables the generation of SLM output that is intrinsically stable [1]. The underlying mechanism was harnessed for the development of two compact Raman laser configurations which were realized as external standing-wave cavities, without use of any mode-selective elements, and containing only the CVD diamond Raman-active gain medium. Efficient frequency conversion of a tunable Yb-fiber-amplified distributed feedback (DFB) laser emitting around 1064 nm to the first-and second-order Stokes components produced SLM output in the near-infrared spectral region at powers up to 7 W, while wavelength tuning over a range of 700 GHz was accomplished by varying the temperature of the DFB pump laser, as depicted in Fig. 1a.