Investigation of SOA-assisted Sagnac recirculating shift register switching characteristics

On the feasibility of full pattern-operated all-optical XOR gate with single semiconductor optical amplifier-based ultrafast nonlinear interferometer

“…8 depicts the effect on the Q-factor of the SOA small signal gain whose contribution is taken into account as it determines, through the influence that it exerts on the dynamic response of this nonlinear element to the inserted data pulses, the extent of the gain change provoked by the latter and subsequently the amount of the differential phase shift induced in the considered interferometric arrangement. From its inspection it is clearly noticed that the obtained curve follows the increase of this parameter in a monotonous ascending manner, with basic reason for this behaviour the fact that higher values of G ss have a drastic impact on the gain variation [43] and are accompanied by a larger differential gain between the orthogonally polarized clock components capable of imparting the phase difference dictated by the truth table Fig. 6.…”

“…For the same reason the SOA has at its disposal less effective time with respect to the bit period for gain recovery, thereby facilitating the manifestation of unwanted patterning on the switched-out pulses. In contrast, the evolution of the obtained curve reveals that much narrower pulses, generated for example from a mode-locked semiconductor ring laser [42] but inevitably with a higher complexity, are favourable to significantly enhance the Q-factor since the gain transitions between the lower and higher saturated dynamic states become steeper [43].…”

On the design of semiconductor optical amplifier-assisted Sagnac interferometer with full data dual output switching capability

“…Concerning first the T-port, it is seen that this parameter must lie within a dynamic range of about 6.5 dB defined by the crossing points in the limit where Q¼6. This can be understood by recalling that it determines the extent of the gain variation in the SOA nonlinear response [48], which in turn induces a certain amount of differential phase shift converted to an output by the interferometer. Thus if G ss is below the left extreme then the CW and CCW components experience a gain around the same, low saturation level, impeding the creation of an adequate Dj.…”

Study on the instantaneous frequency deviation of pulses switched from semiconductor optical amplifier–assisted Sagnac interferometer

“…3, which has been derived as described in Ref. 39 for the interval where 99% of the control pulse total energy has transit the SOA. 5 Moreover, this region includes the one recommended for the achievement of proper single-rail switching with an SOA-based-type interferometric module, 4,5 which essentially means that the incorporated SOA can operate in the same manner.…”

“…4,5,8,17,32,39 Thus, there is not an absolute reason or restriction for this choice, and the method of analysis adopted here can also be followed for its counterpartsnamely, the Mach-Zehnder interferometer ͑MZI͒ 40 and the ultrafast nonlinear interferometer ͑UNI͒. 41 This happens because the detailed comparison between them 42-44 has revealed that none is ideal, but each has its own advantages and disadvantages with respect to defined operational criteria, and depending on the special needs of a particular application, the most appropriate should be preferred.…”