Techniques for analyzing symmetric and asymmetric polarized modes in coupled photonic crystal waveguides are presented. The techniques employed include the plane wave method (PWM) and the finite-difference time-domain (FDTD) method. Two variants of a photonic crystal directional coupler consisting of air holes in silicon are discussed. Additionally, fabricated photonic crystal directional couplers are characterized and experimental results are presented. Applications for photonic crystal directional couplers include frequency-selective filters, dispersion compensators, and optical switches. © 2003 Society of Photo-Optical Instrumentation Engineers.