Self-mixing DFB Velocimeter with 3-dB Fiber Coupler

Abstract

Two beam irradiation scheme enables Doppler velocity measurement using a laser diode without the information of the irradiation angle. By combining the self-mixing effect of a laser diode and the two beam irradiation, the measurement system can be very simple and compact. In this paper, this scheme was demonstrated by using a pig-tail 1.55 pm DEB laser diode and a 3-dB fiber coupler. It was confirmed that the velocity measurement with high precision was possible without the irradiation angle information.