1. Field of the Invention
The invention concerns lasers and, more particularly, power lasers.
With reference to FIG. 1, it is recalled that a laser is generally constituted by an amplifier medium 10 placed in a cavity, the ends of which are constituted by mirrors M1 and M2, one of them (the output mirror M2) being partially transparent to the wavelength emitted by the laser.
The amplifier medium 10 has active ions that may be excited by a pumping source 12 (which is often an auxiliary pumping laser). This source has the function of exciting the electrons of the active ions from a particular energy level to a higher level from which they may fall back, directly or indirectly, to the first level, in emitting photons at a determined wavelength or in a determined range of wavelengths, and with phase coherence.
An aim of the invention is to improve the possibilities of making lasers, notably with respect to the way in which the amplifier medium is excited, either to facilitate emission at a well-determined frequency or to make the emission frequency tunable by simple means.
2. Description of the Prior Art
It may be pointed out that the defects of presently existing power lasers include, for example, the fact that they have several resonance modes so that they tend to emit several wavelengths, some of which are undesirable. Ancillary means (birefringent filters, references, etc.) are therefore required to eliminate these wavelengths, and these means result in an increase in the complexity of the laser, and in a loss of power when the elimination is done by filtering.
It can also be pointed out that, to obtain a tunable laser (whether or not it is a power laser), it is generally necessary to use filters, with temperature adjustment means in order to carry out the tuning. These too are means that are complicated and generate power losses.