Influence of magnetic field on level of linearly polarized laser beam passing through faraday crystal

Influence of magnetic field (B) on level of linearly polarized laser beam is of great importance in many modern applications, such as the field of spectrum, communications and sensors. We have studied the influence of magnetic fields of an amplitude of 0.32 T at 2 cm air-gap on the level of linearly polarized laser beam passing through the Faraday crystal. The Magnetic field was projected parallel and perpendicular on the axis of the Faraday crystal. A control system containing electronic circuit and thermal base to control on the stability of the injection current and the temperature of the semiconductor laser diode (SLD) respectively have designed. The operational direct current (DC) and an alternating current (AC) were used in this study. After inserted Faraday crystal between the poles of the magnetic field generator, the rotation of the polarization angle was investigated, the Verdet constant was calculated, and the output pulse distribution of the SLD was studied. The results show that any increase of magnetic field leads to increase in the rotation angle of the polarization. The Verdet constant has founded depend on the value of the magnetic field and the wavelength of laser. Finally, the expansion of Full Width Half Maximum (FWHM) and Peak Channel Number Shift (PCNS) for one channel has indicated the presence of a magnetic field of 14.6 mT and 2.6 mT respectively, and this led also the peak of the pulse to drop by a rate 461.24 a.u./T.