We demonstrate a novel scheme to control the excitation symmetry for an odd mode in a photonic crystal waveguide and investigate the spectral signature of this slow light mode. An odd-mode Mach–Zehnder coupler is introduced to transform mode symmetry and excite a high-purity odd mode with 20 dB signal contrast over the background. Assisted by a mixed-mode Mach–Zehnder coupler, slow light mode beating can be observed and is utilized to determine the group index of this odd mode. With slow light enhancement, this odd mode can help enable novel miniaturized devices such as one-way waveguides.
© 2012 Optical Society of America
Original Manuscript: May 4, 2012
Revised Manuscript: June 5, 2012
Manuscript Accepted: June 8, 2012
Published: July 25, 2012
Jun Tan, Ming Lu, Aaron Stein, and Wei Jiang, "High-purity transmission of a slow light odd mode in a photonic crystal waveguide," Opt. Lett. 37, 3189-3191 (2012)