Figure 4
(a) Normalized transmission spectra of the on-chip WDM filters. The λres of four rings are marked. (b) Zoom in transmission spectra for ch1 and ch2 and electrical tuning of ch2 with gate biases. The black curve is the spectrum at 0 V, and color curves show the different biases applied on ch2. (c) λres map with the applied biases. The dashed lines show the initial λres of channels (at 0 V), and the color curves show the λres of channels shift. (d) Transmission spectrum of the on-chip WDM filters showing the application of gate bias on each channel (color dashed curves) to compensate for the non-uniform channel spacing caused by fabrication errors (black solid curve).
