Temperature stabilized dielectric based on-chip interferometers

A device comprising:

• a dual-geometry waveguide structure comprising two coupler structures that are optically coupled using first and second arms characterized by total optical path lengths LU and LL respectively, providing an optical path length difference value LO=LU−LL;
• wherein the first arm comprises:
• a first passive waveguide, having a first length and a first waveguide geometry comprising a dual-core geometry of two cores separated by a spacer layer, and being characterized by a first temperature dependence of refractive index dn1/dT;
• a second passive waveguide, having a second length and a second waveguide geometry comprising a single-core geometry, and being characterized by a second temperature dependence of refractive index dn2/dT lower than dn1/dT;
• and
• a first tapered transition structure of length Lt directly coupling the first and second passive waveguides;
• wherein the second arm comprises:
• a third passive waveguide having a third length and the first waveguide geometry, and being characterized by dn1/dT;
• a fourth passive waveguide having a fourth length and the second waveguide geometry, and being characterized by dn2/dT;
• and
• a second tapered transition structure of length LT directly coupling the third and fourth passive waveguides;
• wherein a first confinement factor characterizing an optical mode supported by the first and third passive waveguides is larger than a second confinement factor of an optical mode supported by the second and fourth passive waveguides;
• and
• wherein the first, second, third, and fourth lengths are selected such that a temperature sensitivity characterizing the dual-geometry waveguide structure is lower than a temperature sensitivity characterizing a single-geometry waveguide structure having the same optical path length difference value LO between first and second arms would be, in which all passive waveguides in either the first arm or the second arm are of a single-core geometry or of a dual core geometry, but not both.