Theoretical study on phase conjugation in weakly injected vertical-cavity surface-emitting lasers

This paper gives a detailed theoretical investigation on phaseconjugation induced by nearly degenerate four-wave mixing in singlemode vertical-cavity surface-emitting lasers (VCSELs) with weakoptical injection. Considering VCSELs that can work in linearlypolarized or elliptically polarized states, it derives thetheoretical expression of the conjugated field by small signalanalysis based on the vectoral rate equations---the spin-flip model.For linearly polarized state, VCSELs show similar conjugate spectrato edge-emitting semiconductor lasers. For the ellipticallypolarized state, dichroism and birefringence parameters as well asthe spin-flip rate can change the conjugate spectra. Especially, whenfrequency detuning of the probe and pump waves is between thepositive and negative relaxation oscillation frequency, changes areevident. For specific values of parameters, conjugate efficiencybetween 20,dB to 40dB are obtained.