This paper presents the abnormal phenomena of the feedback fringes detected in the primary output direction compared to those detected in the rear of the laser. These abnormalities appear as the waveform deformation or abnormal phase. Experiments and calculations are carried out to investigate the mechanisms of such phenomena. It is found that they are mainly caused by the interference effects or signal superposition, both of which are introduced by the optical elements in the external cavity. Some approaches are taken to avoid those effects. And then the normal feedback fringes are attained in different detection positions, with similar waveform and phase.
© 2011 Optical Society of America
Lasers and Laser Optics
Original Manuscript: February 28, 2011
Revised Manuscript: July 4, 2011
Manuscript Accepted: July 5, 2011
Published: August 1, 2011
Peng Zhang, Shulian Zhang, and Yidong Tan, "Fringe abnormality induced by the external interference effect in laser feedback," Appl. Opt. 50, 4581-4586 (2011)