Fox-Smith cavity

In a more detailed discussion the absorption losses of the beam splitter BS cannot be neglected, since they cause the maximum reflectance R of the Fox-Smith cavity to be less than 1. Similar to the derivation of (4.76), the reflectance of the Fox-Smith selector, which acts as a wavelength-selecting laser reflector, can be calculated to be [5.53]... 

Figure 5.37b exhibits the reflectance / max for 0 = 2m7r and the additional losses of the laser resonator introduced by the Fox-Smith cavity as a function of the beam splitter reflectance / bs- Tho finesse F of the selecting device is also plotted for R2 = R3 = 0.99 and Abs = 0.5%. The spectral width Av of the reflectivity maxima is determined by... 

Often a Michelson interferometer coupled by a beam splitter BS to the laser resonator is used for mode selection (Fig. 5.39). The free spectral range 8v = c/(L2 + Li) of this Fox-Smith cavity [341] again has to be broader than the width of the gain profile. With a piezoelement PE, the mirror M3 can be translated by a few microns to achieve resonance between the two coupled resonators. For the resonance condition... 

Often a Michel son interferometer is used for mode selection, coupled by a beam splitter St to the laser resonator (Fig.6.16). The free spectral range of this "Fox-Smith cavity" [6.13], which is AX=c/[2(L2+L )], has... 

He-Ne laser oscillating at A = 0.63 ym is selected by a Fox-Smith cavity (see Sect.6.5) with a frequency which can be continuously tuned through the gain profile of the laser transition. The output from a 1.15 ym He-Ne laser is sent col linear with the 0.63 ym beam through the gas discharge and is separated from the 0.63 ym by a prism. The attenuation or amplification of the 1.15 ym beam is detected as a function of the laser frequency and of the inversion n(3 2) - n(2P ), which can be altered by controlling the discharge conditions. The authors call this spectroscopic technique "tuned differential sepctroscopy". 

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