In a general aspect, a vapor cell is presented that includes a dielectric body. The dielectric body has a surface that defines an opening to a cavity in the dielectric body. The vapor cell also includes a vapor or a source of the vapor in the cavity of the dielectric body. An optical window covers the opening of the cavity and has a surface bonded to the surface of the dielectric body to form a seal around the opening. The seal includes metal-oxygen bonds formed by reacting a first plurality of hydroxyl ligands on the surface of the dielectric body with a second plurality of hydroxyl ligands on the surface of the optical window.

The frequency stability of an optical local oscillator is improved by locking a laser to a silicon Fabry-Perot cavity operating at a temperature near 124 K, where the coefficient of thermal expansion of silicon is near zero. The cavity is mounted inside a cryostat housed in a temperature-stabilized vacuum system that is surrounded by an isolating enclosure and supported by an active vibration platform. Laser light is steered with a superpolished mirror toward a superpolished focusing optic that couples the laser light into the cavity. Light reflected from the cavity is used to stabilize the laser via the Pound-Drever-Hall technique, while light transmitted through the cavity is used to stabilize the laser power. A resonant transimpedance amplifier allows the laser power to be reduced, which reduces heating of the cavity caused by residual absorption of the light.

A physics package for an atomic clock is provided herein. The atomic clock may include a resonance cell storing alkali vapor having first and second hyperfine ground states and an excited state, a light source to transmit light through the resonance cell at a frequency corresponding to electronic decay from the excited state to the first ground state, and a photodetector to receive light from the light source. The physics package may include a laser, and controller circuitry to, at a first time, allow light from the laser to optically pump the alkali vapor from the first hyperfine ground state to the excited state; and at a second time, allow the photodetector to receive light source light from the resonance cell while inhibiting light from the laser from optically pumping the alkali vapor in the resonance cell.

A physics package for an atomic clock is provided herein. The atomic clock may include a resonance cell storing alkali vapor having first and second hyperfine ground states and an excited state, a light source to transmit light through the resonance cell at a frequency corresponding to electronic decay from the excited state to the first ground state, and a photodetector to receive light from the light source. The physics package may include a laser, and controller circuitry to, at a first time, allow light from the laser to optically pump the alkali vapor from the first hyperfine ground state to the excited state; and at a second time, allow the photodetector to receive light source light from the resonance cell while inhibiting light from the laser from optically pumping the alkali vapor in the resonance cell.

The invention relates to methods for fabricating antireflective surface structures (ARSS) on an optical element using a seed layer of material deposited on the surface of the optical element. The seed layer is removed during or after the etching, and serves to control etching time as well as the transmission region of the optical element having ARSS. Optical elements having ARSS on at least one surface are also provided.

The invention relates to methods for fabricating antireflective surface structures (ARSS) on an optical element using a seed layer of material deposited on the surface of the optical element. The seed layer is removed during or after the etching, and serves to control etching time as well as the transmission region of the optical element having ARSS. Optical elements having ARSS on at least one surface are also provided.

This oscillator comprises: a source generating an incident optical wave at a pulsation frequency ω; an optomechanical resonator, having optical resonances at the pulsation frequency ω and mechanical resonances at a frequency f.sub.1 and generating, from the incident optical wave, emergent optical waves at the pulsation frequencies ω and ω−2πf.sub.1, and an acoustic wave at frequency f.sub.1; and, a photodiode delivering a useful signal at frequency f.sub.1 from the emergent waves. This oscillator further comprises: an acoustic propagation means for propagating the acoustic wave over a distance in order to produce a delayed acoustic wave; a means for converting the delayed acoustic wave into a delay signal at the frequency f.sub.1; and, a control loop, processing the delay signal in order to obtain a control signal applied to the source.

A vapor cell which can increase the S/N ratio of light as a signal and has high accuracy and a vapor cell manufacturing method are provided. The vapor cell includes: a reflection space (14) provided so as to be able to store a gas containing an alkali metal atom; and an incident light reflection surface, an in-plane reflection portion (17), and an emission light reflection surface provided inside the reflection space (14). The incident light reflection surface has an elevation angle of 45° from an optical path plane so that the incident light incident from a predetermined external direction is reflected in the optical path plane that is perpendicular to the incident light. The in-plane reflection portion (17) has a reflection surface that reflects the reflected light from the incident light reflection surface, the reflection surface being substantially perpendicular to the optical path plane so that the reflected light from the incident light reflection surface is reflected in the optical path plane once or multiple times. The emission light reflection surface has an elevation angle 45° from the optical path plane so that the reflected light from the in-plane reflection portion (17) is reflected in a direction substantially perpendicular to the optical path plane and an emission light is emitted to the outside.

A physics cell includes a sealed glass vial that contains a high-purity dipolar gas (e.g., OCS) at a low pressure (e.g., between about 0.01 millibar and 0.2 millibar). The vial can be sealed using a laser cutting process that involves only local heating of the vial that does not denature the bulk of the contained gas. One or more electromagnetically translucent windows or vial-end access points provide access to electromagnetic waves launched or received by one or more electromagnetic antennas at a frequency that is adjusted to match the quantum transition frequency of the gas based on a detected maximum absorption frequency. The glass-vial physics cell can be fabricated at lower cost than physics cells fabricated from bonded wafers. Multiple vials can be joined by a waveguide in an enclosure so that launch and receive antennas can be provided at a single end of the vials.

A physics cell includes a sealed glass vial that contains a high-purity dipolar gas (e.g., OCS) at a low pressure (e.g., between about 0.01 millibar and 0.2 millibar). The vial can be sealed using a laser cutting process that involves only local heating of the vial that does not denature the bulk of the contained gas. One or more electromagnetically translucent windows or vial-end access points provide access to electromagnetic waves launched or received by one or more electromagnetic antennas at a frequency that is adjusted to match the quantum transition frequency of the gas based on a detected maximum absorption frequency. The glass-vial physics cell can be fabricated at lower cost than physics cells fabricated from bonded wafers. Multiple vials can be joined by a waveguide in an enclosure so that launch and receive antennas can be provided at a single end of the vials.