A polarimetric heterodyning fiber grating laser is proposed to sense a magnetic field. When a magnetic field is parallel to the fiber grating laser, a circular birefringence is induced into the laser cavity. An elliptical birefringence results due to the circular birefringence and the intrinsic linear birefringence of the laser cavity. The elliptical birefringence is translated to the beat note frequency between the two orthogonally polarized laser outputs after photodetection. Confirmed by experiment results, it shows that the beat note frequency shift is proportional to the square of the magnetic field magnitude. Because the fiber laser is as short as less than 2 cm, a miniature magnetic field sensor is then demonstrated in principle.
© 2013 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: December 18, 2012
Manuscript Accepted: January 22, 2013
Published: February 25, 2013
Linghao Cheng, Jianlei Han, Zhenzhen Guo, Long Jin, and Bai-Ou Guan, "Faraday-rotation-based miniature magnetic field sensor using polarimetric heterodyning fiber grating laser," Opt. Lett. 38, 688-690 (2013)