Optical Method of Laser Radiation Modulation Using a Resonance Transition From an Excited State

The presence of different modulators within a cavity often leads to increased losses and is bound by temporal limitations. Therefore, it is reasonable to investigate alternative optical approaches to modulate and control radiation parameters. We propose an optical method for laser radiation modulation based on the use of an excited-state absorption (ESA) transition in a laser active medium under the action of resonant radiation from an external control source. The special features of this method are demonstrated by numerical simulations based on a generalized laser model with the minimum number of parameters. A comparison with the data obtained by detailed simulation of the generation dynamics of a holmium fiber laser demonstrated the matching of the key physical features. The obtained data allow us to understand the limitations of such an approach for different types of lasers. The experimental results confirm the successful application of the proposed method in a holmium fiber laser under exposure by the external pulsed control radiation at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\lambda }_c} \simeq $</tex-math></inline-formula> 1.6 μm, corresponding to the ESA transition <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">⁵I₇→⁵I₅</i> in holmium-doped fiber.