Copyright 2019 SPIE. When a part of light emitted by a laser is back-reflected or back-scattered from an external target and re-enters the laser cavity, both the laser intensity and its wavelength can be modulated. This is so-called self-mixing effect (SME), the optical feedback interferometry (OFI) utilizes such effect in an LD developed various applications. In this paper, we use a dualcavity OFI system that operating in period one state, the laser intensity from this system exhibits an oscillation with its amplitude modulated by a traditional single cavity OFI signal. The dual-cavity OFI system has the same measurement resolution as the single cavity which is half laser wavelength. This paper developed a method to improve the resolution by using fringe subdivision. Our simulation result shows that this method can achieve subnanometer resolution.
Y. Ruan, B. Nie, Y. Yu, J. Xi, Q. Guo, J. Tong & Z. Chen, "Achieving high resolution measurement using laser diode operating at period one," Proceedings of SPIE - The International Society for Optical Engineering, vol. 11197, 2019.