Waveform distortion and Doppler frequency broadening of self-mixing signal in polymer fiber-optic VCSEL system - art. no. 683829

The influences of polymer optical fiber (POF) on self-mixing signals in laser Doppler velocimetry are investigated in detail. The waveform distortion and Doppler frequency broadening of self-mixing signal have been observed for the first time. It indicates theoretically and experimentally that the large acceptance angle of POF facet is the major reason for this phenomenon. The other characteristics of POF, such as bend radius over 7.5mm and thermal effect at room temperature, don't cause significant signal distortion. Lastly, we demonstrated a compact fiber-optic self-mixing laser Doppler vibrometer with high accuracy of half optical wavelength and long working distance between fiber facet and diffusing target adopting a single-longitudinal mode vertical-cavity surface-emitting laser (VCSEL).