Self-switching in Mach-Zehnder interferometers with SOA phase shifters

Abstract

Abstract-A self-switching mechanism in Mach-Zehnder interferometers (MZIs) is described. The input light signal is distributed unequally over the interferometer arms using an multimode interference (MMI) coupler. In the arms, semiconductor optical amplifiers are placed as nonlinear phase shifters. Unequal intensities yield a nonlinear phase shift. The signals from the two arms are then recombined in an output MMI coupler. If an obtained nonlinear phase shift in the arms can compensate the coupler-induced phase difference between the arms, the signals are in phase at the output port. Choosing an appropriate output coupler, 2 1 and 2 2 devices can be obtained. The 2 2 and 2 1 MZIs can be used as pattern effect compensators and 2R-regenerators or low-loss combiner circuits, respectively. An active-passive integration technique is applied in order to realize the interferometric structures. Fabrication, simulation, and characterization of these devices are presented in this letter.

Optical self-switching based on a semiconductor-optical-amplifier-assisted Sagnac interferometer

“…1). Note that the proposed SISS is completely different than the SOA-based MZI self-switch structure already presented [5]. In the MZI-based self switch, each data pulse propagates alone in the MZI's arms without any counterpropagation pulse.…”

“…To our knowledge, the SOA-based Sagnac switches presented so far are considered to be symmetric structures with 3 dB couplers, and SOA-based self-switches have been proposed only in Mach-Zehnder interferometer (SOA-MZI)-based structures. SOA-MZI self-switching has been used to perform various tasks, such as all-optical timedomain label recognition [4] and pattern effect compensation [5], and in low-loss optical combiners [6].…”

InP-based photonic circuits: Comparison of monolithic integration techniques

“…These effects can also be used for self-phase modulation, e.g. in a self-switching optical combiner [14]. A basic function is the generation of light in a PIC.…”

Operational Equivalence of Self-Switching in MZI and Nonlinear Polarization Switches Based on SOAs

“…We note that this model reduces to the one adopted for the polarization insensitive SOA provided that birefringence is set to zero (i.e., the TE and TM gains are equal and the imbalance factor is set to 1). In this case, (7) and (7-8) reduce to (5) [18]. However, we used two different models for computational efficiency [only (5) must be solved in the case of polarization insensitive SOAs].…”

“…This makes it unsuitable for most practical implementations. SOA-MZI's can instead be designed to be polarization insensitive [7], [8]. On the other hand, while the power splitting ratio in any SOA-MZI device is fixed at its design stage, the NPS offers the possibility to change its symmetry easily at any time by controlling the input signal polarization; this allows for higher flexibility, and can be very useful in proof-of-concept experiments.…”