Transmittance and time-of-flight study ofAlxGa1−xAs−basedphotonic crystal waveguides

Transmittance spectra and reflectance at a few specific wavelengths of ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}-\mathrm{based}$ air-rod photonic crystal waveguides with partially perforated cladding layer were measured by using a wavelength-tunable cw laser and a time-of-flight method, respectively. A marked drop of the transmittance for TM-like mode is found in the $\Gamma -M$ direction, which arises from a band gap. The overall results for many samples with different parameters can be explained in terms of a model of photonic band structures. The radiation loss out of the plane, which is a key problem for this type of waveguide, increases drastically with an increase of either the number of rows N or the air-filling factor f. Thus it is concluded that only those waveguides with $N=5\mathrm{}$ and $f<~0.35$ might work well for controlling the radiation field in some cases.