Fig. 4: Waveguide samples for transmittance measurement.

a Optical microscope image of the fabricated Z-shaped S = 3 IS-PhCWG. The three segments of the waveguide have lengths 100a, 30a, and 100a. b SEM image of the bending part of a S = −2 IS-PhCWG. c SEM image of the straight part of a S = 1 IA-PhCWG.