Abstract: Embodiments herein describe using a birefringent element (e.g., a half-wave plate, full-wave plate, birefringent crystal, or metasurface) or a band-pass filter to reduce the laser line broadening induced by the soliton self-frequency shift. The birefringent element may a free space element that is part of the laser cavity. Due to dispersion, different frequencies (or colors) of light in the laser travel through the birefringent element at different speeds. This dispersion results in the birefringent element introducing slightly different polarization shifts for the different frequencies of light in the laser. When this light passes through a polarizer (which is set to filter out polarizations different from a desired polarization), the polarizer attenuates or extinguishes the frequencies that do not have the polarization of the design frequency of the birefringent element.

Abstract: Embodiments herein describe spectroscopy systems that use an unmodulated reference optical signal to mitigate noise, or for other advantages. In one embodiment, the unmodulated reference optical signal is transmitted through the same vapor cell as a modulated pump optical signal. As such, the unmodulated reference optical signal experiences absorption by the vapor, which converts laser phase noise to amplitude noise like the other optical signals passing through the vapor cell. In one embodiment, the unmodulated reference optical signal has an optical path in the gas cell that is offset (or non-crossing) from the optical path of the modulated pump optical signal. The unmodulated reference optical signal allows removal or mitigation of the noise on the other optical signal.

Abstract: Embodiments herein describe a continuous wave two-way optical time two-way transfer system. The embodiments herein lock a local frequency comb to a clock (e.g., optical/microwave atomic clock, Fabry-Perot optical reference cavity, etc.) in a local platform. The platform then generates two CW optical signals with different frequencies and locks those optical signals to the local frequency comb. The local platform then transmits its two CW optical signals to a remote platform and receives CW optical signals (having approximately the same frequencies as the two CW optical signals generated by the local platform) from the remote platform. Based on comparing its local CW optical signals with the received CW optical signals, the local platform can determine a timing deviation between its clock and a clock in the second platform.

Abstract: Embodiments herein describe using compressed source material to perform an atomic experiment or an atomic application within a vacuum chamber (e.g., an atom cooling and trapping apparatus). Source material is often refined and sold with dendritic or crystalline surfaces that result in a very large surface area. This surface area increases the likelihood that a large amount contaminants will form on the surface, which is especially true for reactive source materials. To mitigate the risk of contamination, in the embodiments herein the source material is compressed onto a substrate. This changes the material from having a dendritic or crystalline surface to a flat surface, which has a much smaller surface area and thus is less susceptible to contaminants which can, for example, improve the lifetime usage of the source material.

Abstract: Embodiments herein describe combining multiple optical signals so these signals propagate in the same direction in the same optical mode and polarization. In one embodiment, the techniques discussed herein are used to combine a reference laser with a frequency comb so that supercontinuum generation can then be performed to increase the frequency range of the frequency comb so that it includes the frequency of the reference laser.

Abstract: Embodiments herein describe an ASIC design where certain portions of the laser driver are controllable by the user. In one embodiment, the ASIC may include one or more pins which provide a connection interface where the user can electrically connect a sense resistor that corresponds to the particular laser being used. The remaining portions of the laser driver are implemented in the ASIC, thereby giving the user the flexibility to adapt the laser driver to her selected laser while having the advantages that come from using an ASIC.

Abstract: Embodiments herein describe using a birefringent element (e.g., a half-wave plate, full-wave plate, birefringent crystal, or metasurface) or a band-pass filter to reduce the laser line broadening induced by the soliton self-frequency shift. The birefringent element may a free space element that is part of the laser cavity. Due to dispersion, different frequencies (or colors) of light in the laser travel through the birefringent element at different speeds. This dispersion results in the birefringent element introducing slightly different polarization shifts for the different frequencies of light in the laser. When this light passes through a polarizer (which is set to filter out polarizations different from a desired polarization), the polarizer attenuates or extinguishes the frequencies that do not have the polarization of the design frequency of the birefringent element.

Abstract: Embodiments herein describe peak detection techniques for selecting an absorption line to lock a spectroscopy laser in a frequency reference (e.g., an atomic clock). In one embodiment, an atomic reference is used which has many absorption lines within a relatively small frequency range (e.g., within a gain profile of the spectroscopy laser). The peak detection techniques can evaluate which of these lines a laser can be locked to. For example, the peak detection algorithm can define a preferred absorption line. But if for some reason the spectroscopy laser cannot be locked to the preferred absorption line, the peak detection technique has at least one backup absorption line. By having a set of candidate absorption lines, the peak detection algorithm can identify a suitable absorption line for lasers with different gain regions, or as gain regions change.

Abstract: Embodiments herein describe generating signals for stabilizing a frequency comb using a PIC that contains a two-segment supercontinuum generator waveguide (SGW). A first segment of the SGW is designed to spread the spectrum of the frequency comb so that a significant portion of the spectral intensity of the frequency comb is at double the original frequency of the frequency comb. A second segment of the SGW is designed to spread the spectrum of the frequency comb so that a significant portion of the spectral intensity of the frequency comb is at a frequency of a reference laser.

Abstract: Embodiments herein describe spectroscopy systems that use an unmodulated reference optical signal to mitigate noise, or for other advantages. In one embodiment, the unmodulated reference optical signal is transmitted through the same vapor cell as a modulated pump optical signal. As such, the unmodulated reference optical signal experiences absorption by the vapor, which converts laser phase noise to amplitude noise like the other optical signals passing through the vapor cell. In one embodiment, the unmodulated reference optical signal has an optical path in the gas cell that is offset (or non-crossing) from the optical path of the modulated pump optical signal. The unmodulated reference optical signal allows removal or mitigation of the noise on the other optical signal.

Abstract: Embodiments herein describe an atomic sensor that includes a photonic die that outputs optical signals on a top surface. These optical signals can be directed and shaped as needed to satisfy a particular type of atomic sensor. In one embodiment, an atomic source (e.g., rubidium or cesium) is disposed on the photonic chip to emit atoms when heated. A collimator can then direct the emitted atoms along a path that intersects with the optical signals. This intersection can be used to detect motion (e.g., rotation and acceleration) of the atomic sensor.

Abstract: Various disclosed embodiments include collimated beam atomic ovens, collimated atomic beam sources, methods of loading a source of atoms into an atomic oven, and methods of forming a collimated atomic beam. In some embodiments, an illustrative collimated beam atomic oven includes: a tube having a first portion and a second portion; a source of atoms disposed in the first portion of the tube; an aperture disposed in the second portion of the tube; a heater assembly disposable in thermal communication with the tube; and an openable seal disposed in the tube intermediate the source of atoms and the aperture.

Abstract: Disclosed embodiments include laser systems. An illustrative laser system includes a tunable laser. A beam splitter is operatively couplable to an output of the laser and is configured to split light output from the laser into a first path and a second path. A first modulator is disposed in the first path and is configured to generate first set of sidebands. A bandpass filter circuit includes a fiber Bragg grating filter and is operatively couplable to receive output from the first modulator and to pass a selected sideband of the first set of sidebands. A lock circuit is disposed in the second path, is configured to determine and stabilize wavelength of the laser, and is further configured to cooperate with the fiber Bragg grating filter to maintain a static lock point for the laser while allowing output of the first path to be tunable with respect to the lock point.

Abstract: Embodiments herein describe sub-picosecond accurate two-way clock synchronization by optically combining received optical pulses with optical pulses generated locally in a photonic chip before the optical signals are then detected by a photodetector to obtain an interference measurement. That is, the optical pulses can be combined to result in different interference measurements. Optically combining the pulses in the photonic chip avoids much of the jitter introduced by the electronics. Further, the sites can obtain multiple interference measurements which can be evaluated to accurately determine when the optical pulses arrive at the site with femtosecond accuracy.

Abstract: Various disclosed embodiments include collimated beam atomic ovens, collimated atomic beam sources, methods of loading a source of atoms into an atomic oven, and methods of forming a collimated atomic beam. In some embodiments, an illustrative collimated beam atomic oven includes: a tube having a first portion and a second portion; a source of atoms disposed in the first portion of the tube; an aperture disposed in the second portion of the tube; a heater assembly disposable in thermal communication with the tube; and an openable seal disposed in the tube intermediate the source of atoms and the aperture.

Abstract: Embodiments herein describe sub-picosecond accurate two-way clock synchronization by optically combining received optical pulses with optical pulses generated locally in a photonic chip before the optical signals are then detected by a photodetector to obtain an interference measurement. That is, the optical pulses can have different repetition rates so that the offset between the received and local optical pulses constantly changes, thereby resulting in different interference measurements. Optically combining the pulses in the photonic chip avoids much of the jitter introduced by the electronics. Further, the sites can obtain multiple interference measurements which can be evaluated to accurately determine when the optical pulses arrive at the site with femtosecond accuracy.