Undamped regular spiking of high energy ruby laser

The spatially independent laser rate equation model is generalized to include multimode effects, and it is also shown that the same description of laser behavior as provided by the single-mode model results. Analytical expressions for the steady-state values of the variables in all modes are derived. It is shown that a singularity at the oscillation threshold exists in the steady-state equations which is responsible for the laser action. It is further demonstrated that the inverted population and the photon density in off-axis modes saturates above threshold, whereas the photon density in the primary mode increases linearly with pump rate above threshold. The exact time-dependent solutions are determined numerically, and it was found that the spiking separation and decay time could change by more than 50 percent of their values at the start of laser emission to the region of steady-state oscillation, even when the pump is assumed to be time independent. The linearized expressions for the spiking parameters are, therefore, inadequate-despite their frequent use-to describe phenomena appearing in the early portions of the spiking trace. A comparison with five experimental cases is also made. It was found that this model, with all modes included, provides no improvement over the single mode model, and cannot account for the irregular or undamped spiking or even the multimode oscillations observed experimentally.

Analysis of the uniform rate equation model of laser dynamics

Multimode oscillation of the ruby laser near threshold

Ruby Laser with Piezoelectrically Excited Vibrating Reflector

This article is confined to a brief review of the present state of laser theory and of resonant cavities, together with a discussion of the present situation in gas and doped-crystal lasers. For the most part, the developments of the last 2-3 years are reported following on the article by Geusic and Scovil in the 1964 issue of this publication. An outline of the general features of Lamb's theory is followed by a discussion of axial modes, relaxation oscillation and of mode locking. Parametric effects are briefly mentioned. Resonant cavities are dealt with fairly fully, including results for anisotropic cavities and for cavities with coupling holes. Discussion of gas lasers is largely confined to helium-neon, ion and molecular gas systems; a bibliography on other gas and vapour lasers is included. The general features of Raman and Brillouin lasers are mentioned in so far as they provide methods of producing lasers at frequencies additional to those corresponding to direct transitions. After a brief introduction to the properties of doped-crystal laser materials, and to a discussion of loss mechanisms (which play a dominant role in the performance of such systems), the properties of trivalent and divalent rare earth ions in various host crystals are examined; actinide and transition metal ions are also briefly dealt with. The article closes with a section on second-harmonic generation, viewed as a source of additional laser transitions.

Doped-crystal and gas lasers

http://ieeexplore.ieee.org/iel5/5/31048/01444218.pdf

T.I. Stocker

Papers

Pulsed oscillations in ruby lasers