Self-mixing speckle interference in DFB lasers

Theoretical analysis and experimental results of self-mixing speckle interference in a distributed feedback (DFB) laser are presented in this paper. Self-mixing speckle interference occurs when external optical feedback comes from a moving rough surface. Dynamic output variations in the DFB laser as well as their probability density functions (PDFs) are analyzed on the basis of speckle theory and self-mixing interference in the DFB laser. Numeric simulations and experiments are in agreement with each other. The both results show that self-mixing speckle interference in DFB laser can be used to measure velocity of target.