Axes Of Quarter-wave Plate Research Articles

Numerical analysis of a dual polarization mode-locked laser with a quarter wave plate

Dynamical behaviors and frequency characteristics of an active mode-locked laser with a quarter wave plate (QWP) are numerically studied by using a set of vectorial laser equation. Like a polarization self-modulated laser, a frequency shift of half the cavity mode spacing exists between the eigen-modes in the two neutral axes of QWP. Within the active medium, the symmetric gain and cavity structure maintain the pulse's circular polarization with left-hand and right-hand in turn for each round trip. Once the left-hand or right-hand circularly polarized pulse passes through QWP, its polarization is linear and the polarized direction is in one of the directions of ±45° with respect to the neutral axes of QWP. The output components in the directions of ±45° from the mirror close to QWP are all linearly polarized with a period of twice the round-trip time.

Polarization-shifting interferometry on two-dimensional linear birefringent parameters measurement

A novel polarization-shifting interferometer in conjunction with a differential phase to amplitude conversion technique is proposed. It is able to determine the linear birefringence vector (LBV) of a quarter wave plate in two-dimension. The LBV consists of the phase retardation and the azimuth angle of fast axis of quarter wave plate. This vector is calculated by the ratio of the amplitudes of the heterodyne signals at different steps of linear polarization shifting. The effect which is due to the error of the polarization-shifting angle on LBV determination is discussed.