  We demonstrate that n-doped resistive heaters in silicon waveguides show
photoconductive effects with high responsivities. These photoconductive
heaters, integrated into microring resonator (MRR)-based filters, were used to
automatically tune and stabilize the filter's resonance wavelength to the input
laser's wavelength. This is achieved without requiring dedicated defect
implantations, additional material depositions, dedicated photodetectors, or
optical power tap-outs. Automatic wavelength stabilization of first-order MRR
and second-order series-coupled MRR filters is experimentally demonstrated.
Open eye diagrams were obtained for data transmission at 12.5 Gb/s while the
temperature was varied by 5 C at a rate of 0.28 C/s. We theoretically show that
series-coupled MRR-based filters of any order can be automatically tuned by
using photoconductive heaters to monitor the light intensity in each MRR, and
sequentially aligning the resonance of each MRR to the laser's wavelength.

Optics