An experimental observation of power and wavelength optical bistability and nonlinear gain in a 1550 nm vertical-cavity semiconductor optical amplifier (VCSOA) operated in reflection and biased above and below threshold is reported. Two distinct types of optical bistability, clockwise and anticlockwise, are observed.
We report experimental measurements of Optical Bistability (OB) and nonlinear switching in a 1550 nm-Vertical-Cavity Semiconductor Optical Amplifier (VCSOA) operated in reflection and biased below and above its threshold current. Two different types of OB and nonlinear switching, anticlockwise and clockwise, have been observed in both the optical power and wavelength domain. The influence of important parameters including the bias current, the initial wavelength detuning and the optical input power has also been studied. The existence of diverse forms of OB and nonlinear switching in a VCSOA operated in reflection opens the door for the development of inverting and non-inverting logic gates, using, respectively, the anticlockwise or the clockwise nonlinear switching transitions appearing in the VCSOA under external optical injection.
We present an overview of the properties and applications of optical bistability in vertical-cavity semiconductor optical amplifiers (VCSOAs). The basic physics and analytical models of this optical nonlinearity are discussed. Experimental results obtained from a VCSOA operated in the 850 nm wavelength region are presented. Counterclockwise hysteresis loops are obtained over a range of initial phase detuning and bias currents. One hysteresis loop is observed experimentally with an input power as low as 2 muW when the device is biased at 98% of its lasing threshold. Numerical simulations based on the Fabry-Perot resonator model and rate equations we developed show good agreement with our experimental observations. In addition, a low input intensity high contrast (10:1) optical and gate and 2R regeneration are demonstrated. We believe that bistable VCSOAs can significantly advance the prospect of a dense two-dimensional array of low-switching-intensity all-optical logic and memory elements.
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.