A generalised ABCD matrix treatment for laser resonators and beam propagation is developed for computer programming. In this treatment, imaginary parts are introduced into the matrixes for all optical elements, and the beam quality factor M2 and the index of the medium are also taken into account. When the imaginary parts of the complex matrix are zero and the beam quality factor M2 and medium index are unity, the stated method is transformed back into the more classic ABCD matrix format in which the fundamental-mode Gaussian beam transmits through real elements in the vacuum. Based on this method, laser resonator software is realised by the VB programme language. The software can be used to analyse and design stable/unstable standing/travelling cavities, phase-conjugate cavities and beam transformations. 相似文献
The two-dimensional Laplace integral transform technique has been applied to get the spatial and temporal temperature distributions in both the molten layer thickness of a thin film coated on a substrate, the still solid part of the thin film of the target and the temperature distribution in the substrate. Also a formula for the time dependence of the evaporated part of the thin film of the target as well as the molten layer thickness of the thin film were obtained. Calculations of the obtained relations were carried out during the irradiation with a pulsed laser. The derivation has taken into account the temperature-dependent absorption coefficient of the irradiated surface and the chemical reaction in the vapor of the thin film. As an illustrative example, computations were carried out on an aluminum thin film coated on a glass substrate. 相似文献
The two-dimensional Laplace integral transform technique has been used to compute the temperature profile of the molten layer on the surface of a semi-infinite target when irradiated by a pulsed laser. Mathematical expressions for the temperature distribution in the molten layer thickness and the solid part of the target, taking cooling and the temperature-dependent absorption coefficient of the irradiated surface into account, were obtained. As an illustrative example computations were carried out on a semi-infinite aluminum (Al) target. 相似文献
Abstract Of the new laser dyes of coumarin series reported earlier, pyrazolo derivatives have been further studied. The paper reports their laser spectra and efficiencies in various solvents compared to a standard coumarin laser dye C515. One of the derivatives shows comparable output under optimum concentration conditions as compared to the standard. 相似文献
Two hundred years after Malus' discovery of optical anisotropy, the study of polarization‐driven optical effects is as active as ever, generating interest in new phenomena and potential applications. However, in ultrafast optics, the influence of polarization is frequently overlooked being considered as either detrimental or negligible. Here we demonstrate that spatio‐temporal couplings, which are inherent for ultrafast laser systems with chirped‐pulse amplification, accumulate in multi‐pulse irradiation and lead to a strongly anisotropic light‐matter interaction. Our results identify angular dispersion in the focus as the origin for the polarization dependence in modification, yielding an increase in modification strength. With tight focusing (NA ≥ ∼0.4), this non‐paraxial effect leads to a manifestation of spatio‐temporal couplings in photo‐induced modification. We devise a practical way to control the polarization dependence and exploit it as a new degree of freedom in tailoring laser‐induced modification in transparent material. A near‐focus, non‐paraxial field structure analysis of an optical beam provides insight on the origin of the polarization dependent modification. However, single pulse non‐paraxial corrected calculations are not sufficient to explain the phenomena confirming the experimental observations and exemplifying the need for multi‐pulse analysis.