Nonlinear Optical Polarization

Igor I. Gancheryonok, Andrei V. Lavrinenko

Jan Danckaert, Hugo Thienpont A, Irina P. Veretennicoff

To merge the fields of polarization and nonlinear optics opens wide perspectives. The present work aims at investigating some of them. It is shown, on one hand, that if a nonlinear Fabry- Perot resonator filled with an optically isotropic material is addressed by an obliquely incident beam, the transmitted irradiance can switch from an up to a down state (or the reverse) if its polarization is properly modulated. If on the other hand the nonlinear cavity is filled with a linearly birefringent material, polarization optical bistability can occur, even at normal incidence. This polarization bistability can arise both by modulating the incident irradiance and by modulating the incident polarization. Optical bistability of the transmitted irradiance can also be induced by the modulation of the polarization of the incident beam. All these features provide new tools for parallel digital optical information processing.

Werner H. Lauterborn, Thomas Kurz, Martin Wiesenfeldt

Werner H. Lauterborn, Thomas Kurz

Antonio Hurtado, Ian D. Henning, M.J. Adams

Experimental observation of Optical Bistability (OB) and nonlinear gain is reported in a 1550-nm Vertical Cavity Semiconductor Optical Amplifier (VCSOA) under parallel and orthogonal polarized optical injection into the two orthogonal polarizations of the fundamental mode. Different nonlinear switching mechanisms, including anticlockwise and clockwise nonlinear gain and bistability, have been found when the polarization of the externally injected signal matches that of the injected mode, whilst a linear response is measured when the polarization is orthogonal to that of the mode under injection. This diversity of behavior with input polarization offers promise for the potential use of VCSOAs for all-optical signal processing and all-optical switching/routing applications.

Jelena Dimitrijević, D. Arsenović, B. M. Jelenkovic

We study numerically the nonlinear magneto-optical rotation of polarization (NMOR) of the laser pulse during its propagation through a cold Rb cloud with induced Zeeman coherences and electromagnetically induced transparency. Evolution of NMOR is calculated by solving the Maxwell–Bloch equations. We consider a linearly polarized Gaussian pulse with different pulse peak amplitudes and widths. For an intensity peak of 5 mW cm−2 and full-width at half-maximum of 10 μs, transient behaviour of NMOR does not follow the pulse intensity variation: NMOR begins to decrease as the pulse's intensity nears its peak value. When the pulse has a smaller peak intensity, NMOR behaves qualitatively differently: the angle of rotation constantly increases during the pulse propagation. Observed differences are explained by the optical pumping into the dark state and the behaviour of the ground-state coherences subjected to coherent population trapping. The same pulse intensity, from different sides of the pulse, during rising and falling sides, produces qualitatively different NMOR shapes, its amplitudes and widths which result can be explained by the successive excitation of atoms during the pulse propagation. It was shown that increasing the relaxation rates of the ground-state coherences, shifts the maximum of the NMOR to higher magnetic field, while the atomic density strongly influences the magnitude of the NMOR.