Dynamics of polarization switching in 1550nm-VCSELs under single and double optical injection

We analyze the time dependent dynamics associated with the Polarization Switching (PS) induced in a 1550nm-Vertical Cavity Surface Emitting Laser (VCSEL) subject to polarized optical injection. We have investigated two different experimental configurations, namely single and double polarized optical injection into the 1550nm-VCSEL with polarizations parallel and orthogonal to that of the light emitted by the solitary device. We have simultaneously analyzed the temporal dynamics for the two orthogonal polarizations at the VCSEL output. Sub-ns response times were obtained for both experimental configurations. For single orthogonally-polarized optical injection we found that the operation speed is ultimately limited by the relaxation oscillation frequency of the VCSEL. On the other hand, with the device subject to double polarized optical injection a significantly enhanced operation speed was obtained. We believe that this improved time response is due to the faster carrier dynamics associated with the switching between the two injectionlocked states induced alternatively by the two polarized optically-injected signals. This enhanced operation speed for the PS attained in VCSELs at the important telecom wavelength of 1550nm offers exciting prospects for novel uses of these devices in optical signal processing and optical switching applications in present and future optical networks.