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(Color online) Chip-scale atomic magnetometer. (a) Schematic of the magnetic sensor. The components are (1) VCSEL; (2) polyimide spacer; (3) optics package including (from bottom to top) a neutral-density filter, polarizer, a quartz quarter wave plate, and a neutral-density filter; (4) ITO heater; (5) vapor cell with rf coils above and below it; and (6) ITO heater and photodiode assembly. (b) Photograph of the magnetic sensor. Note the gold wire bonds providing the electrical connections from the baseplate to the device.
(Color online) (a) Photograph and (b) schematic side view of the ITO heater. Two glass substrates with patterned ITO are glued together with a nonconductive epoxy to make a heater with reduced magnetic fields. The lighter color lines in the heater are where ITO has been removed through laser patterning. After the ITO patterning, gold pads are deposited for wire bonding, and a insulating layer of benzocyclobutene is deposited over the remaining exposed ITO so that electrical contact between the upper and lower ITO layers is made only through the gold pads. The large arrows show where the current enters and exits the heater. The electrically conductive epoxy provides the connection between the upper and lower ITO.
Response of the magnetometer is plotted as a function of frequency when a chirped modulation is applied to the static field. Inset: The in-phase lock-in amplifier output as a function of magnetic field where the frequency of the applied rf field is .
Noise density of the lock-in signal converted to units of magnetic field. The lock-in time constant is with a filter rolloff /octave. The ambient field is .
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