Synthesis of laser resonator configurations as an inverse problem in optics

Abstract

In this paper, we present a comprehensive study on the potentials and limitations of high repetition rate pulsed laser deposition (PLD), using a diode-pumped solid state (DPSS) Nd : YAG laser, operated at 532 nm. Titanium oxide thin films were deposited at 5 Pa of oxygen on silicon substrates with a different number of pulses, typically several tens of millions, and at pulse repetition rates (PRR) between 10 and 30 kHz, while keeping the pulse energy at a constant value. The lateral variation of thickness, void content and optical parameters along the radii of the circularly symmetric films were measured by spectroscopic ellipsometry and atomic force microscopy images were taken to reveal the surface topography of the films. In contrast to the conventional, i.e. low repetition rate PLD, the optical and topographical properties of the films were found to be uniform within an area of approximately 50 mm in diameter, while a decrease in the roughness of the films was evidenced towards the edges. The effects of an inherent property of DPSS lasers, namely the interrelated nature of PRR and pulse duration, were investigated. By means of a simple thermal model, it was shown that careful consideration of the characteristics of the laser is required to explain the experimentally revealed trends in the PRR dependence of the film growth rate.

High-Power Optics

“…In the regimes of 'modulation' and 'phase conjugation' the amplitudes of local displacements of the reflecting surface should reach 0.1 − 0.5 0 and 1 − 5 0 , respectively. To ensure such displacement amplitudes we proposed adaptive POE actuators of new types, which are made of magnetostrictive materials and implement the conditions for the Joule and Wiedemann effects [73][74][75][76][77][78]. At the same time we pointed out the prospect of creation of compact highly efficient actuators, providing a stable amplitude displacement in the frequency range up to 10 kHz.…”

“…According to the results of modelling intracavity optical systems [78][79][80][81][82][83][84][85][86], the use of adaptive POEs allows one to obtain the diffraction angular divergence of radiation fluxes when use is made of unstable resonators in high-power carbon dioxide laser systems. Adaptive POEs were essentially a new type of devices ensuring the local control of phase characteristics of coherent radiation fluxes.…”

“…In this part of the review we present the results of the studies on the creation of phase correctors of the beam path for laser systems based on POEs being cooled [79][80][81][82][83][84][85][86]. The shape of the reflecting surface is controlled in this case by the deformation of the porous structure of the heat exchanger.…”

“…This method is simple to implement and is widely used when creating precise adaptive POEs for highpower lasers and astronomical telescopes. At present, adaptive POEs of mirror type were created with an aperture diameter of one meter and the number of control channels (i.e., the number of actuators) up to several hundreds [75][76][77][78][79][80][81][82][83][84][85]. The study of adaptive POEs showed the versatility and high efficiency of this method for obtaining aberration-free fluxes of coherent radiation.…”

High-power optics and its new manifestations

“…Third, and in our opinion, the most promising line of laser diode assemblies is the creation of a phase-locked diode array [50][51][52][53][54][55][56]. The output radiation of such a laser is a set of narrowly focused interference peaks (in particular one peak) with a small divergence.…”