Chip-scale atomic gyroscope

#Field of the Invention

#Embodiments disclosed herein relate generally to atomic sensing devices, and more specifically, to a chip-scale atomic gyroscope or magnetometer.

#Description of the Related Art

#So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

#FIG. 1 illustrates a cross-sectional view of a chip-scale atomic device, according to a first embodiment.

#FIG. 2 illustrates a polarization analyzer of the chip-scale atomic device, according to the first embodiment.

#For clarity, identical reference numbers have been used, where applicable, to designate identical elements that are common between figures. It is contemplated that features of one embodiment may be incorporated in other embodiments without further recitation.

#Embodiments of the present invention are directed to atomic sensing devices. The atomic sensing devices will be described herein primarily in relation to chip-scale atomic gyroscopes. It is to be understood, however, that embodiments of the atomic sensing devices may be used instead as magnetometers without departing from principles of the present invention.

#A first embodiment provides a chip-scale atomic gyroscope having high performance, in terms of bias stability and ARW, as well as small size and low power usage. The chip-scale atomic gyroscope includes a vapor cell forming a closed gas cell containing one or more active NMR isotopes, alkali atoms, and optional buffer gas. The chip-scale atomic gyroscope also includes a light source encircled by a polarization-selective photodetector assembly and a light reflective surface opposite the light source, forming a multiple light path through the vapor cell between the light source, the light reflective surface, and the polarization-selective photodetector assembly. The chip-scale atomic gyroscope further includes a quarter-wavelength optical phase retarder (“quarter-wave plate” or “λ/4 plate”) which serves two functions: (1) circularly polarizing diverging light emitted by the light source to produce a pump beam for optically pumping alkali atoms, which in combination with orthogonal magnetic fields (or a modulating of the light from the light source) causes the alkali atoms and NMR isotope atoms to precess about the magnetic field; and (2) rotating the polarization of a returning, linearly polarized probe beam so that the signals arriving at the photodetector assembly produce roughly equal signals in each of the orthogonal polarization channels. Alternatively, the quarter-wave plate may be positioned so that it circularly polarizes light emitted by the light source for optical pumping but does not intersect the probe beam. In addition, the chip-scale atomic gyroscope includes a polarization analyzer comprising four quadrants, each of which is a polarizing beam splitter that separates incident light into S and P components. These S and P component signals may optionally be purified using linear polarizers, and the orthogonal S and P polarizations for each quadrant are then measured to determine a rotation of the polarization of the probe beam due to interactions with precessing atoms in the vapor cell. The rotation of the polarization of the probe beam, as observed in the rotating frame of the gyroscope, may itself be used to determine a rotation of the gyroscope with respect to an inertial frame.