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This paper presents a novel algorithm for measuring the linewidth enhancement factor of semiconductor lasers and the optical feedback level factor in a semiconductor laser with an external cavity. The proposed approach is based on analysis of the self-mixing phase equation to deduce equations for finding parameters given only knowledge of the perturbed phase. The effectiveness of the method has been validated with accuracy of 8.6%and 1.7% for 'C' and alpha respectively while covering all feedback regimes.