Optical cavity design

The light generated by stimulated emission is usually identical to the light that stimulates it in wavelength, phase, and polarization. This gives laser light its characteristic coherence and allows it to maintain the uniform polarization and (often) monochromaticity allowed by the optical cavity design. 

The word laser is an acronym for light amplification by the stimulated emission of radiation. Lasers of all kinds consist of several basic components an active medium, an outside energy source, and an optical cavity with carefully designed mirrors on both ends. One of the mirrors is 100 percent reflective... 

B. Agate, B. Stormont, A.J. Kemp, C.T.A. Brown, U. Keller, and W. Sibbett, Simplified cavity designs for efficient and compact femtosecond Cr LiSAF lasers. Optics Communications 205,207-213 (2002). 

To illustrate some of the considerations involved in designing a simple optical cavity, we consider the low gain He-Ne system operating at 6328 A. We assume that the design aim is to obtain the maximum output power on the TEMqq mode. We arbitrarily choose a discharge tube of length 80 cm, and... 

We have seen in preceding sections that the diffraction losses in optical cavities can be reduced to negligible values by careful design. However, all practical resonators have finite losses associated with the output transmission at the mirrors and so the Q of the cavity, defined by... 

The designs for several small-scale cw HF(DF) chemical lasers have been given in the literature. " These devices deliver power outputs of a few watts when operated with mixtures of H2(D2), SFe, and helium. Operation as an HCl chemical laser is also possible in this type of laser with either the Cl + HI > HCl + I or H + CI2 -> HCl + Cl reactions, albeit with somewhat lower power outputs than the HF(DF) lasers. Figure 3.8 illustrates one such device. An electrical discharge of about 1 kW(DC, RF, or micro-wave) is commonly used for dissociation of SFg to provide a source of F atoms. Hydrogen is injected by means of small orifices in a direction transverse to the primary flow of partially dissociated SFg in a helium diluent. The optical cavity is aligned transversely to the flow direction as shown in Figure 3.8. The output of such lasers usually consists of several P-branch transitions in the 1 ->0, 2-> 1, or 1 ->0, 2-> 1, and 3->2 bands for HF or DF, respectively. Operation as an HCl laser produces P-branch transitions in the... 

---