Transverse pattern modifications in a stable apertured laser resonator

Abstract

The effects of hard apertures on the transversal mode distribution and the output near and far field distributions are investigated both theoretically and experimentally. Wavefronts propagating in different directions inside a CO(2) laser cavity were measured at the same plane and found to have different transversal amplitude profiles. The influence of intracavity aperture's location and diameter on the near field distribution and far field beam quality were measured and calculated. Quantitative figures of merit are introduced to evaluate the departure of the transversal mode patterns from ideal Gaussians.

End-to-End Transmission Analysis of Simultaneous Wireless Information and Power Transfer using Resonant Beam

“…From these positions (new wave sources), the wavelets are emitted. The field distribution at a position in space is the result of coherent superposition of these wavelets at that position [18,24,25]. The expression of this theory can be depicted as Fresnel-Kirchoff's diffraction integral:…”

Spatial properties of a diffracted high-order radial Laguerre–Gauss LGp0beam

“…The selected fundamental mode is no longer Gaussian in shape due to the diffraction both inside [8][9][10] and outside [10][11][12] the laser cavity. The main result that we have to remember from these and many other studies is that when a Gaussian laser beam is incident upon a circular aperture the emerging beam is highly perturbed in the region of the nearfield [13], and again becomes quasi-Gaussian in shape in the far-field [14].…”

Observing mode propagation inside a laser cavity

“…The peculiarity is that, due to diffraction upon the mode selecting aperture, the forward and backward beams can be very different in a given plane. This is in fact the design principle behind unstable resonators [3,4], but has received very little attention in the case of stable resonator systems, and this almost always theoretical [11][12][13][14][15][16]. Unfortunately the literature almost exclusively concerns itself with the transverse shape of the mode at the output coupler plane of the laser or at least at one of the two mirrors, whereas as we explain later, these planes do not allow for an experimental observation of the differences in the two counter-propagating beams.…”

“…Unfortunately the literature almost exclusively concerns itself with the transverse shape of the mode at the output coupler plane of the laser or at least at one of the two mirrors, whereas as we explain later, these planes do not allow for an experimental observation of the differences in the two counter-propagating beams. Some attempts have been made to experimentally study the beam propagation external to the cavity in order to infer the behavior of the counter-propagating waves inside the resonator cavity [15][16][17][18], but to date there has been no experimental study on the full propagation of the forward and backward beams inside a laser cavity.…”