Abstract: Embodiments herein describe spectroscopy systems that provide frequency, amplitude, and power-stabilized light to a vapor cell. An optical signal can be split into two optical paths where a first optical path includes an AOM to perform frequency and amplitude modulation to generate a pump optical signal and a second optical path that includes a variable optical attenuator (VOA) for generating a probe optical signal. These optical signals can then be provided into a vapor cell (also referred to as a gas cell) to perform spectroscopy.

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 a path length adjuster for, e.g., adjusting the length of an optical cavity of a laser. In one embodiment, the path length adjuster includes a circulator element for ensuring unidirectional lasing. The path length adjuster may also include one or more focusing elements such as a focusing lens and/or a collimator which directs received laser light at a mirror. The mirror is mounted on an actuator that moves the mirror in a direction parallel with the propagation of the laser light, thereby increasing or reducing the length of the ring cavity.

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 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 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 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: 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: 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.