Deep-levels in silicon waveguides: a route to high yield fabrication

In this paper we outline two recent results which demonstrate the utility of deep-level engineering in silicon photonics. We describe the integration of silicon waveguide p-i-n photo-detectors in a ring (or race-track) resonator structure. The detectors are made sensitive to wavelengths around 1,550 nm via the introduction of deep-levels into the intrinsic volume of the waveguide detector. By exploiting the multiple-pass of the optical signal through the detector, we are able to significantly decrease the size of the detector structure (relative to straight waveguide detectors) while maintaining excellent responsivity on resonance. We also describe the use of deep-levels for optical modulation. Preliminary results show that thallium doped silicon waveguides may be switched between a dark and transparent condition through the variation of phosphorus doping. It is suggested that active devices may be fabricated in such a way as to vary the occupancy of the thallium level through field mediated modulation. The straightforward fabrication methods described lend themselves to a high-volume, high yield manufacturing process which should find general applicability in wavelength division multiplexing systems.