Analysis of power-dependent switching between radiatively coupled planar waveguides

Abstract

Effective coupling between two remote optical waveguides without branching sections can be achieved in a three-guide system with multimode central waveguide. We investigate the nonlinear power switching of c.w. laser radiation by such radiatively coupled waveguides. It is shown that effective all-optical switches with spatially well separated input/output channels can be realized although the influence of multimode interference on the switching characteristics becomes more pronounced for increasing thickness of the central guide. Different coupling regimes are specified, and the changes in switching characteristics during the transformation from one regime to another is studied. Numerical calculations for the critical power are compared with an approximate analytical expression. It is also shown that, at a moderate input power, a small number of modes determines the switching behavior.

Pulse Response of Nonlinear Multimode Interference Couplers

“…4(b) and 5(b), the results obtained using Model-II (dotted line) are also presented for comparison. Although these two couplers can be initially in the cross state or the bar state, these states are attained by incorporating the difference in propagation constants β 0i in (19) correctly. Compared with the results shown in Figs.…”

Anisotropic leaky-like perturbation with subwavelength gratings enables zero crosstalk

“…While the mode is propagating, the spread of these radiations enables coupling with other devices even when they are far apart. This radiative coupling provides a major advantage in directional couplers 43 – 45 and polarization splitters 46 , as the coupling length remains short with increasing separation distance. But it also proves to counteract when it comes to unwanted waveguide crosstalk, as the cladding radiation significantly enhances the coupling strength between waveguides.…”

Kerr nonlinear effects in AlGaAs multimode waveguides

“…Even a simple photonic component such as a multimode waveguide can exhibit interesting properties, particularly when operated in the nonlinear regime. 8,9 We highlight that it would be virtually impossible to inject enough power to affect the linear self-imaging by using a single-mode input waveguide. The physical mechanism exploited to generate multiple images of the input light distributions is the excitation and subsequent propagation of a specific set of modes along the longitudinal axis of the waveguide.…”

“…8,9 The devices used in our experiment were ridge waveguides etched 1.1 m deep into an epitaxial wafer formed by an Al 0.18 Ga 0.82 As core layer sandwiched between two Al 0.24 Ga 0.76 As cladding layers. 8,9 The devices used in our experiment were ridge waveguides etched 1.1 m deep into an epitaxial wafer formed by an Al 0.18 Ga 0.82 As core layer sandwiched between two Al 0.24 Ga 0.76 As cladding layers.…”