Polarization sensitivity is a major problem in microphotonics, because the polarization state changes randomly in optical fibres. This makes SC microphotonic devices incompatible with the optical fibres necessary to connect them to the outside world. SC microphotonics should not be confused with microphotonics using weak confinement of light, such as those based on doped-silica waveguides and ridge waveguides, as these may be fabricated to be individually polarization transparent10, 11, 12. This is impossible for SC microphotonic devices as it would require fabrication with subatomic absolute dimensional accuracy (see Supplementary Information). Ridge waveguides, even those made in silicon, are not considered part of SC microphotonics as they offer a weak lateral field confinement that results in substantial bending loss and, consequently, in large resonator size. However, a ridge waveguide etched so deep that it resembles a rectangular waveguide and shares a similar level of confinement will ... exhibit similar challenges in polarization transparency.