Standing-wave saturation resonances

C. Freed and A. Javan, "Standing-Wave Saturation Resonances in the COj 10.6 y Transitions Observed in a Low-Pressure Room-Temperature Absorber Gas," App. Phys. Lett. J 7, 53 (1970). 

Fig.5.24a-d. Spatial intensity distribution for two standing waves with slightly different wavelengths X and A.2 (a), (b), and their corresponding saturation of the inversion AN z) (c). Explanation of spatial hole-burning modes in the active medium (d) with a small length L, close to a resonator mirror Ml (a< b)... 

A laser mode represents a standing wave in the laser resonator with a z-de-pendent field amplitude E(z) as illustrated in Fig.5.20a. Since the saturation of the inversion aN, discussed in the previous section, depends on the inten-sity I JE, the inversion saturated by a single laser mode will exhibit a spatial modulation aN(z) as drawn in Fig.5.20c. Even for a completely homogeneous gain profile, there are always regions of unsaturated inversion... 

Fiq.5.20a-c. Spatial hole burning Field distributions of two standing waves with slightly different wave lengths along the resonator axis and the resultant spatial modulation of the inversion due to gajn saturation... 

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