Coupled-Mode Analysis of a T-Branch Waveguide with a Wavelength-Selective Reflection Feedback.

The operation of T-branch waveguides with a wavelength-selective reflection feedback is analyzed using theoretical and numerical analysis. The coupled-mode theory (CMT) is employed to drive the necessary conditions for achieving perfect transmission. The analytic results reveal that the reflection to the input port is absent when the phase-shift of the electromagnetic waves traveling between the cavities is equal to (2n+1)π/2 and the decay rates into the three ports are equal. The finite-difference time-domain (FDTD) simulation results of the modified T-branch which is implemented in two dimensional photonic crystals (2D-PC), show that the analysis is valid. The proposed structure might also be valuable for design of other integrated optical functions. [ABSTRACT FROM AUTHOR]