Leonid N. Kaptsov

Doughnut-like laser beam output formation by intracavity flexible controlled mirror

The formation of the given low loss and large beamwidth doughnut-like fundamental mode of stable resonator by an intracavity flexible mirror is discussed. The mirror is a bimorph one with one round and two ring controlling electrodes. An inverse propagation method is used to determine the appropriate shape of the controlled mirror. The mirror reproduces the shape with minimal RMS error by combining weights of experimentally measured response functions of the mirror sample. The voltages applied to each mirror electrode are calculated. The calculations are carried out for industrial CW CO2 laser.

Super-Gaussian laser intensity output formation by means of adaptive optics

An optical resonator using an intracavity adaptive mirror with three concentric rings of controlling electrodes, which produc low loss and large beamwidth super-Gaussian output of order 4, 6, 8, is analyzed. An inverse propagation method is used to determine the appropriate shape of the adaptive mirror. The mirror reproduces the shape with minimal RMS error by combining weights of experimentally measured response functions of the mirror sample. The voltages applied to each mirror electrode are calculated. Practical design parameters such as construction of an adaptive mirror, Fresnel numbers, and geometric factor are discussed.

Active laser resonators - computer simulation and practical realization

Summary form only given. The given laser intensity distribution could be formed by different methods - both extracavity and intracavity. The main advantage of the intracavity method is not only the possibility to form the desirable intensity structure but to increase the total power of the laser radiation. One of the well-known approach is to apply graded reflectivity mirrors. But such mirrors introduce sufficient intrinsic power losses and can be used only in lasers with large gain of active medium (mostly with unstable resonators). It was suggested then to extend the same fabrication technology for making graded-phase mirrors which can be used in stable laser cavities for the given intensity output formation. However the main drawback of such mirrors is the rigidity of their surface profile, so every change of laser parameters needs the special mirror to be made and applied. For the purpose of formation of a specified laser output we used an intracavity flexible mirror composed of a semipassive bimorph element, made in IPLIT Russian Academy of Sciences.