The effects of self-mixing interference on gain-coupled (GC) distributed-feedback (DFB) lasers are analyzed. From coupled-wave theory, the oscillation frequency and threshold gain variations are theoretically deduced. The influences on self-mixing from the coupling length coefficient, the linewidth enhancement factor of the GC DFB laser, and the reflection coefficient of the external reflector are discussed along with numerical analysis and are compared with the effects of self-mixing interference of λ/4 phase-shifted DFB lasers and Fabry�??Perot (F-P) lasers. Our results show that high-accuracy self-mixing sensors can be obtained with GC DFB lasers.
© 2005 Optical Society of AmericaPDF Article