As an important part of almost all laser systems, optical film is so fragile that easy to damage because of
temperature rise. Based on temperature field theory and thermal conduction equation, the physical model of
temperature field of multiplayer films illuminated by Gaussian laser is built. By solving the Maxwell equation, the
average energy flow rate of plane wave with unit intensity propagation through the films is obtained. The numerical
calculation program of the temperature field of multiplayer films illuminated by 1064nm laser is built using
alternating direction-implicit technique. The simulation results show that laser spot radius, heat exchange coefficient,
laser power and film material have a great effect on the temperature field of multiplayer films. These are the key
factors to damage the optical films. The results obtained in this paper would be both theoretical basis and reference
for optical thin film components developing.
The laser diode(LD) beam propagate through the collimating lens is studied here beyond the paraxial approximation, the
ray from the LD entering the lens at coordinates on one face emerges at approximately the same coordinate on the
opposite face. The lens delays an incident wavefront by an amount proportional to the thickness of the lens at each point,
Further propagation of this field can be adequately represented by the calculation of the Rayleigh-Sommerfeld (RS)
diffraction integral, and the stationary-phase method is employed in order to find the asymptotic expansion of the
diffraction integral. The propagation optical field after the lens is obtained. The model employed to predict the light
intensity at various beam cross sections.
A new model is applied to describe the field distribution at the output of the
LDAs. Formalism describing of the far-field radiation patterns of a laser arrays is
presented, base on rigorous solutions of the Helmholtz equations. The
beam-divergence angles normal and parallel to the junction plane are concluded.
Theoretical results presented are in close agreement with the experiments. and the
final result is expressed in a form convenient for diffraction analysis of LDAs beams.
Beam quality is very important in laser technology and its application. In practice a good beam quality evaluating method can indicate which beam is good and which laser is suitable. Therefore evaluating beam quality is of huge significance. Because the beam of laser diode has many characteristics differ from other lasers, such as the angle of the beam is too big, and the angle in the direction parallel to the junction plane disagrees with it in the perpendicular direction, a new quality parameter Q(θ,ω,d) for evaluating beam quality of laser diode is given. The difficulty of collimation is well expressed by use of Q. The smaller the value of Q is, the more easily the beam is collimated.
The propagation characteristics of Hermite-cosine-Gaussian beams passing through an ABCD optical system with hard-edge aperture is studied, by means of expansion of the window’s function of the hard-edge aperture into a finite sum of complex Gaussian functions, the approximate analytical propagation equations of laser beams are derived. This method is superd in its reduction of computing time, together with the convenience it furnished in analyzing physically the propagation properties of laser beams.
Based on the analysis of the beam output characteristics of laser diodes, using the generalized Collins integral, the propagation characteristics of Hermite-Gaussian beams passing through a gradient index lens is studied. The analytical expressions of intensity distribution is derived and numerical examples is illustrated. it furnished in analyzing physically the propagation properties of the beams of laser diodes.