Magnetometer and method of fabrication

An optical magnetometer comprising:

• an optical resonator having optical modes and mechanical modes, the optical resonator having a central void;
• a tunable laser producing optical radiation at a laser frequency locked to an optical mode frequency of he optical resonator and coupled into the optical resonator;
• a magnetostrictive material located in the central void such that a change in dimension of the magnetostrictive material causes a change in mechanical modes of the optical resonator;
• and
• an optical detector that detects changes in the optical radiation due to changes in the mechanical modes.

A method of fabricating an optical magnetometer including the steps of:

• depositing a ring of photoresist on a silicon wafer having a thermally grown silica top layer;
• transferring the pattern into the silica layer with a buffered oxide HF etch;
• etching the silica layer with XeF2 to form a silica disk with a central void;
• reflowing the silica disk with a CO2 laser to form a silica torus;
• and
• bonding a disk of magnetostrictive material into the central void with epoxy, the disk having a diameter of approximately, but no greater than, the diameter of the central void.