Frequency-shifted dynamics of Nd:YVO4 laser with anisotropic and quite weak optical feedback

Abstract

The dynamic response of single-mode a-cut Nd:YVO4 laser combined with linearly polarized oscillation and orthogonally polarized optical feedback is investigated. Under frequency-shifted of 2 MHz, the output laser exhibits amplitude and phase modulation with anisotropic feedback when arbitrary retarder is inserted in external cavity. Its response characteristics vary with both phase retardation and optical axis orientation of the retarder. The amplitude response coefficient (ARC) and the phase response coefficient (PRC) are introduced to describe the response characteristics. In the special case where phase retardation equal to π/2, there is the minimum value in ARC and jump in PRC. Based on the Jones matrix of birefringent external cavity and rate equations of micro-chip laser, theoretical analysis of the frequency-shifted dynamics is carried out, in which the amplitude and phase response coefficient bridge the measurement and simulation quite well. Under different feedback level, the response limit of micro-chip laser with anisotropic feedback is verified as low as 10-9 of the reinjected light.

Keywords

• Laser feedback
• Self-mixing interference
• Birefringence