Ring laser

A ring laser [5,19] utilizes an optical resonator consisting of at least three reflecting surfaces which can be provided by mirrors or prisms. 

A unidirectional ring laser also avoids the unwanted hole-burning effects in inhomogeneous gain profiles of active media in Fabry-Perot type resonators, which are caused by the fact that the wave travelling into the z direction is absorbed by molecules with a velocity component v = +(v - Vq)c/vq, but the reflected wave by other molecules with v = -(v - Vq)c/vq (see Sects. 

If the whole ring laser is placed on a revolving platform the frequency of the two waves running in opposite directions is split due to the Sagnac effect [5.201. The frequency difference Av = - v is proportional to 

In Sect.5.4 we saw that the radial intensity distribution of a laser oscillating in the fundamental mode has a Gaussian profile. The laser beam emitted through the output mirror therefore also exhibits this Gaussian intensity profile. Although such a nearly parallel laser beam is in many respects 

A laser beam travelling into the z direction can be represented by the field amplitude 

---

H.P. Weber, R. Ulrich, A Ihin-film ring laser Appl. Phys. Lett. 1971, 19. 3b. 

Fig. 12.12 Comparison between the shifts in the emitted wavelength of a CBNL and a conven tional ring laser for changes in the ambient refractive index...

Figure 3.25. Laser resonators applicable to molecular glasses A = microdroplet, B = microdisk, C = ring laser, D = vertical cavity distributed bragg laser, E = distributed feedback laser, F = random laser.

We have developed FM lasers based on a commercial ring laser (Coherent 699-21). In this case all the intracavity etalons are removed and replaced by a lithium niobate phase modulator. This modulator can be resonantly driven at a frequency close to the cavity mode spacing. A simple theory of FM operation of a laser suggests that the modulation index is given by [12]... 

Figure 7. Tunable dimer ring laser scheme.

---