Low current plasma effect optical switch on InP

Multimode interference couplers with tunable power splitting ratios

“…We first determined the free-carrier absorption losses with increasing current bias. The theory of the carrier absorption implies that for not too high currents, the losses are approximately linear to the current density such that we can write with reasonable accuracy with mA cm (5) where losses in units of cm ; applied current bias in units of mA; experimentally determined loss constant. Comparison of simulation with experiment also allowed us to approximate the refractive index change as a function of the applied current.…”

“…Standard couplers that allow for tuning of the splitting ratios include digital-optical switches like -and -junctions [5] or directional couplers [6]. But digital-optical switches are large and require precise lithography at waveguide intersections.…”

Multimode interference photonic switches

“…3. 18 The active region ͑electro-or thermo-optic region͒ is used to change the relative phases among the arms, which can realize the switching [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] or tunable power splitting function at the outputs. 22 Generally, the MZI switches are based on Y-junction, directional coupler and MMI.…”

“…32 On the other hand, directional couplers need tight ͑ϳ0.1 m͒ control of the waveguide dimensions since they exploit mode coupling between two waveguides that are close to each other. 33 When compared with directional couplers, MMI couplers show better uniformity, polarization insensitivity, 5 and bandwidth and fabrication tolerances 3 and are more suitable for an MZI-type optical switch. Second, with a Y-junction, MMI couplers show better polarization insensitivity and fabrication tolerances.…”

GaAs based long-wavelength microring resonator optical switches utilising bias assisted carrier-injection induced refractive index change

“…In addition, CI switches are polarisation independent [9] and have been implemented using Mach-Zehnder interferometer (MZI) and Directional Coupler (DC) configurations [10]. Despite their simplicity in operation, CI switches (MZI or DC type) have large device foot-prints, and hence, they are impractical for use in large-scale integrated systems [11,12].…”