251results about "Gaseous masers" patented technology

A clock including: a portable, at least partially evacuated housing; a cell being positioned within the housing and including an internal cavity having interior dimensions each less than about 1 millimeter, an intra-cavity pressure of at least about 760 Torr, and containing a metal atomic vapor; an electrical to optical energy converter being positioned within the housing to emit light through the metal atomic vapor; an optical energy intensity detector being positioned within the housing to receive the light emitted by the converter through the metal atomic vapor; at least one conductive winding around the cavity to stabilize the magnetic field experienced in the cavity dependently upon the detector; and, an output to provide a signal from the housing dependently upon the detector detecting the light emitted by the converter through the metal atomic vapor.

A chip scale atomic clock is disclosed that provides a low power atomic time/frequency reference that employs direct RF-interrogation on an end-state transition. The atomic time/frequency reference includes an alkali vapor cell containing alkali atoms, preferably cesium atoms, flex circuits for physically supporting, heating, and thermally isolating the alkali vapor cell, a laser source for pumping alkali atoms within the alkali vapor cell into an end resonance state by applying an optical signal along a first axis, a photodetector for detecting a second optical signal emanating from the alkali vapor cell along the first axis, a pair of RF excitation coils for applying an RF-interrogation signal to the alkali atoms along a second axis perpendicular to the first axis, a pair of bias coils for applying a uniform DC magnetic field along the first axis, and a pair of Zeeman coils for applying a Zeeman interrogation signal to the alkali atoms and oriented and configured to apply a time-varying magnetic field along the second axis through the alkali vapor cell. Another flex circuit is used for physically supporting the laser source, for heating the laser source, and for providing thermal isolation of the laser source. The laser source can be a vertical cavity surface emitting laser (VSCEL). The bias coils can be Helmholtz coils.

Providing: quickly brining a vapor cell 119 to a desired temperature when retaining the heat of the vapor cell 119 to enhance the magnetic field detection performance of an optically pumped magnetometer; preventing adherence of atoms in the vapor cell 119 to a laser irradiation light passing-through part of the vapor cell 119; downsizing the periphery of the vapor cell 119; and suppressing the effect of a magnetic field from a heater used to retain the heat of the vapor cell 119. The present invention includes: a transparent film heater 118 provided to a laser irradiation light passing-through part of a vapor cell 119, the vapor cell 119 being a magnetic detection part of the optically pumped magnetometer; a temperature detector 115 provided at a center part of a side of the vapor cell 119; a temperature regulator 111 that sets a desired temperature for heat retention of the vapor cell 119 and compares the desired temperature and the actual temperature of the vapor cell measured by the temperature detector 115; an operation unit 112 that upon receipt of a PID control signal for temperature control from the temperature regulator 111, performs a temperature adjustment and switches on/off, in a pulsed manner, current applied to the transparent film heater 118 after the desired temperature is reached; and a heater power supply 113 that upon receipt of an operation signal from the operation unit 112, applies current to the transparent film heater 118.

The present invention provides a method and apparatus for making atomic clocks or atomic magnetometers as self-modulated laser systems based on the physics of push-pull optical pumping. An atomic vapor cell is required to be in the laser cavity. With proper conditions, spontaneous push-pull optical pumping can occur inside the laser cavity. This causes the laser beam to be modulated at hyperfine-resonance frequency. With a fast photodetector, the modulated laser signal can be converted into the electrical signal, which serves as the atomic clock ticking signal or magnetometer signal. The self-modulated laser system does not use any local oscillator and the microwave circuit to lock the oscillator frequency to the hyperfine-resonance frequency, and therefore can consume less power and become more compact than conventional systems. This invention will benefit applications of time measurements and magnetic-field measurements.

An atomic clock having a physics package that includes a vacuum chamber cavity that holds atoms of Rb-87 under high vacuum conditions, an optical bench having a single laser light source, a local oscillator, a plurality of magnetic field coils, an antenna, at least one photo-detector and integrated control electronics. The single laser light source has a fold-retro-reflected design to create three retro-reflected optical beams that cross at 90° angles relative to one another in the vacuum chamber cavity. This design allows the single laser light source to make the required six trapping beams needed to trap and cool the atoms of Rb-87. The foregoing design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.

A CPT detector and a method for detecting CPT are disclosed. The CPT detector includes a quantum absorber, a polarization analyzer, and a detector. The quantum absorber includes a material having first and second low energy states coupled to a common high energy state. Transitions between the first low energy state and the common high energy state and between the second low energy state and the common high energy state are induced by electromagnetic radiation having a predetermined polarization state. The polarization analyzer blocks electromagnetic radiation of the predetermined polarization while passing electromagnetic radiation having a polarization state that is orthogonal to the predetermined polarization. The polarization analyzer is irradiated with a portion of the generated electromagnetic radiation that has passed through the quantum absorber. The detector generates a signal related to the intensity of electromagnetic radiation that leaves the polarization analyzer.

The present invention provides a method and system to simultaneously use the microwave and Zeeman end resonances associated with the same sublevel of maximum (or minimum) azimuthal quantum number m to lock both the atomic clock frequency and the magnetic field to definite values. This eliminates the concern about the field dependence of the end-resonance frequency. In an embodiment of the system of the present invention, alkali metal vapor is pumped with circularly-polarized D₁ laser light that is intensity-modulated at appropriate resonance frequencies, thereby providing coherent population trapping (CPT) resonances. In another embodiment, pumping with constant-intensity circularly-polarized D₁ laser light enhances magnetic resonances that are excited by alternating magnetic fields oscillating at appropriate resonance frequencies. In both embodiments, the resonances are greatly enhanced by concentrating most of the atoms in the initial state of the resonances, and by diminishing the spin-exchange broadening of the resonances. This leads to greater stability of optically pumped atomic clocks. This invention can also be used to operate an atomic magnetometer, where the feedback signal used to stabilize the magnetic field at the alkali-vapor cell can serve as a sensitive measure of the ambient magnetic field.

A system is disclosed for charging a compact vapor cell, including placing an alkali-filled capillary into a reservoir cell formed in a substrate, the reservoir cell in vapor communication with an interrogation cell in the substrate and bonding a transparent window to the substrate on a common face of the reservoir cell and the interrogation cell to form a compact vapor cell. Capillary action in the capillary delays migration of alkali in the alkali-filled capillary from the reservoir cell into the interrogation cell during the bonding.

The present invention discloses a miniaturized rubidium atomic frequency standard cavity-cell system, wherein, a microwave cavity cylinder is made from high magnetic permeability material; the microwave cavity cylinder is sleeved with a heating cylinder; a pump light incident port of the heating cylinder is also provided with a convex lens which gathers and transmits rays emitted by a rubidium spectral lamp into a microwave cavity; a C field coil is directly wound on a dielectric cylinder arranged between the microwave cavity cylinder and an absorption cell; a cusp on the tail part of a light-filtering cell is concentrated at the center of a circular plane at the end of the cell; a cusp on the tail part of the absorption cell is concentrated at the edge of a circular plane at the end of the cell; a photocell and a snap-off diode are fixed on the end face of the inner wall of a cavity end cover which can be movably fixed. The present invention has no machinery regulating rod inside the cavity, uses an intracavity frequency doubling mode, adopts a cylindrical TE111 mode and a dielectric filling method to get rid of the complex structure of a magnetic shield cylinder in the prior art, and reduces the volume of the cavity-cell system. As the pump light incident port of the heating cylinder is provided with the convex lens to increase the light intensity of pump light, the performance of the cavity-cell system is guaranteed. A mobile photoelectric component is adopted for cavity frequency fine adjustment, which is convenient for debugging and cannot cause field form distortion.

An atomic oscillator is disclosed, including an Alkaline metal cell, a light source illuminating a laser beam to the Alkaline metal cell, and a light detector detecting light passing through the Alkaline metal cell. The Alkaline metal cell includes a first member, a second member, a cell internal portion, and an Alkaline metal raw material. In the first member, a first glass substrate is bonded on a second surface of a first substrate where a first opening part is formed. In the second member, a second glass substrate is bonded to a fourth surface of a second substrate where a second opening part is formed. The cell internal portion is formed by the first opening part and the second opening part by bonding the first surface to the third surface. The Alkaline metal raw material is enclosed by the cell internal portion.

A physical section of an atomic oscillator includes at least: a gas cell including a cylindrical portion and first and second windows respectively hermetically-closing openings of both sides of the cylindrical portion to form a cavity in which gaseous metal atoms are sealed; a light reflection unit disposed on the first window; a first heating unit disposed to be closely attached to the second window and heating the gas cell at a predetermined temperature; a light source disposed so as to allow a light emitting part thereof to face the light reflecting unit, emitting excitation light exciting the metal atoms in the gas cell, and provided on a side, which is a reverse side to a side to which the gas cell is provided, of the first heating unit; a light detection unit detecting the excitation light reflected by the light reflection unit and provided also on a side, which is a reverse side to a side to which the gas cell is provided, of the first heating unit; and a Peltier element interposed between the light source and the first heating unit, and between the light detection unit and the first heating unit.

A quantum interference device for causing an electromagnetically induced transparency phenomenon to occur in an alkali metal atom by a resonant light pair including a first resonant light and a second resonant light, includes: a light source to generate a plurality of the first resonant lights different from each other in frequency by Δω and a plurality of the second resonant lights different from each other in frequency by Δω; a magnetic field generation unit that applies a magnetic field to the alkali metal atom; a light detection unit that detects intensities of lights including the first resonant lights and the second resonant lights passing through the alkali metal atom; and a control unit that controls to cause a frequency difference between the specified first resonant light and the specified second resonant light to become equal to a frequency difference corresponding to an energy difference between two ground levels of the alkali metal atom based on a detection result of the light detection unit, wherein the control unit controls at least one of the frequency Δω and intensity of the magnetic field generated by the magnetic field generation unit to satisfy at least one of 2×δ×n=Δω and Δω×n=2×δ (n is a positive integer) with respect to a frequency δ corresponding to an energy difference between two Zeeman split levels different from each other in magnetic quantum number by one among a plurality of Zeeman split levels generated in each of the two ground levels of the alkali metal atom by energy splitting due to the magnetic field.

A rubidium atom oscillator is not influenced by a circumference noise or the like, and is excellent in the short-term stability and the phase noise characteristic. A crystal oscillator oscillates a fixed frequency as an atomic resonance frequency. A direct digital synthesizer inputs an output of the crystal oscillator as a system clock and also inputs tuned data corresponding to an error signal generated according to a resonance frequency so as to carry out a variable control of an output frequency. A frequency synthesizer synthesizes and multiplies an output of the direct digital synthesizer and applies a phase modulation with a low-frequency signal. An atomic resonator inputs an output of the frequency synthesizer and detects an error signal with respect to a resonance frequency of rubidium atoms. A tuned-data generating circuit inputs the error signal from the atomic resonator so as to generate the tuned data corresponding to the error signal. The output frequency of the direct digital synthesizer is output from the rubidium atom oscillator.

A device for an atomic clock, including: a laser source (102) that generates a laser beam; a splitter (101) that makes it possible to divert and allow a portion of the laser beam to pass therethrough in accordance with a predefined percentage; a quarter-wave plate (105) that modifies the linear polarization of the laser beam into circular polarization and vice versa; a gas cell arranged on the circular polarization laser beam; a mirror (107) sending the laser beam back toward the gas cell (106); a first photodetector (108a), and a polarizer (103) arranged between the laser beam outlet and the splitter in order to protect the laser source from the retroreflections emitted by different optical elements constituting the device.