Net gain coefficient

Here, lin and lout denote the intensities of the incoming and outgoing beam, respectively, a is the cross-section for stimulated emission, Nexc is the concentration of excited Si states, and L is the path length of the light in the sample. The term gnet=( exc represents the net gain coefficient of the material. 

The net gain coefficients A and the cross-coupling coefficients C for modes bi depend on the dressed populations by the relations... 

Data compiled by Hanks (1983) show that, contrary to earlier notions, the m coefficient in Equation 1 may be affected by the genotype. A relatively greater net gain of carbon for the same rate of transpiration under stress may be reflected in the m coefficient (Equation 1), in the ratio between assimilation and transpiration (assimilation ratio) or in the agronomic index, WUE (Equation 2). 

Some low-molecular dyes also have been investigated in inactive polymer matrices. For stilbene compounds in polystyrene, peak wavelengths in the green spectral region are obtained, with net optical gain coefficients of g = 15-20 cm-1 [187],... 

If bifimctional molecules do not form glasses, they can be incorporated into polymer binders. Examples of bifunctional molecules are shown in Fig. 24. DTNBl (molecule (b) in Fig. 24) was doped in PMMA and Cgg was used as a sensitizer. Diffraction efficiencies of 7%, sub-second grating growth times, and net two-beam coupling gain coefficients of 34 cm" were observed in such samples [81]. DPANST (molecule (c) in Fig. 24) was doped into PBMA [84]. Recently, ms response times were reported in photorefractive glasses based on the bifunctional chromophore DRDCTA (molecule (d) in Fig. 24) doped with the plasticizer DOP (molecule (b) in Fig. 23) and Cgg as a sensitizer [89, 90]. 

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