Effect of laser source nonlinearity on optical heterodyne interferometry

In this paper, an optical heterodyne interferometric detection model with a frequency-ramped laser diode (LD) has been analyzed. The effect of the nonlinearity of the LD source on the optical heterodyne interferometry has been investigated in two different ways, which are the power-distortion Fourier series analysis and the harmonic distortion analysis. The general formulation between the tangent of the tested phase and the interference fringe have been presented with the analysis of the beat signal in the frequency domain by each methodology. The numerical results of these formulations have been presented.