Polarization-independent InP Arrayed Waveguide Grating Filter Using Deep Ridge Waveguide Structure

After the design stage, we fabricated an 8 X 8 TI-AWG. Figure 3 shows the transmission spectra of the TI-AWG with temperature change from 25 to 75°C. Eight transmission peaks are clearly observed. The observed free spectral range is 32.3 nm and peak spacing is 3.8 nm. Even under a relatively high-temperature condition, the peak for each output port remains almost exactly at its position. The wavelength change for all output ports is less than O.lA/'C with the temperature variation of 50°C. This is much smaller than conventional AWGs on InP substrates. In summary, the temperature dependence of the refractive index in InGaAsP compounds are obtained. By using these results in the actual design of a TI-AWG, we achieved temperature sensitivity of less than O.lA/'C, which is more than 10 times smaller than conventional semiconductor devices.