Optical detection of conduction-electron spin resonance in GaAs, ${\mathrm{Ga}}_{1-x}{\mathrm{In}}_x\mathrm{As}$, and ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$

The optical detection of conduction-electron spin resonance (CESR) is performed in GaAs, ${\mathrm{Ga}}_{1-x}{\mathrm{In}}_x\mathrm{As}$, and ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$ alloys. The measured g factor of GaAs is $g^{*}=-0.44\mathrm{}\pm 0.02$. The good precision obtained permits a fruitful comparison with theory. It is shown that such measurements are very sensitive to optically created hyperfine nuclear fields which may shift noticeably the CESR line. A simultaneous nuclear saturation is then mandatory to obtain significant results.