@article{14802,
  abstract     = {Frequency-stable lasers form the back bone of precision measurements in science and technology. Such lasers typically attain their stability through frequency locking to reference cavities. State-of-the-art locking performances to date had been achieved using frequency modulation based methods, complemented with active drift cancellation systems. We demonstrate an all passive, modulation-free laser-cavity locking technique (squash locking) that utilizes changes in spatial beam ellipticity for error signal generation, and a coherent polarization post-selection for noise resilience. By comparing two identically built proof-of-principle systems, we show a frequency locking instability of 5×10<jats:sup>−7</jats:sup> relative to the cavity linewidth at 10 s averaging. The results surpass the demonstrated performances of methods engineered over the last five decades, potentially enabling an advancement in the precision control of lasers, while creating avenues for bridging the performance gaps between industrial grade lasers with scientific ones due to the afforded simplicity and scalability.},
  author       = {Diorico, Fritz R and Zhutov, Artem and Hosten, Onur},
  issn         = {2334-2536},
  journal      = {Optica},
  keywords     = {Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials},
  number       = {1},
  pages        = {26--31},
  publisher    = {Optica Publishing Group},
  title        = {{Laser-cavity locking utilizing beam ellipticity: accessing the 10<sup>−7</sup> instability scale relative to cavity linewidth}},
  doi          = {10.1364/optica.507451},
  volume       = {11},
  year         = {2024},
}

@article{14980,
  abstract     = {Precision sensing and manipulation of milligram-scale mechanical oscillators has attracted growing interest in the fields of table-top explorations of gravity and tests of quantum mechanics at macroscopic scales. Torsional oscillators present an opportunity in this regard due to their remarked isolation from environmental noise. For torsional motion, an effective employment of optical cavities to enhance optomechanical interactions—as already established for linear oscillators—so far faced certain challenges. Here, we propose a concept for sensing and manipulating torsional motion, where exclusively the torsional rotations of a pendulum are mapped onto the path length of a single two-mirror optical cavity. The concept inherently alleviates many limitations of previous approaches. A proof-of-principle experiment is conducted with a rigidly controlled pendulum to explore the sensing aspects of the concept and to identify practical limitations in a potential state-of-the art setup. Based on this study, we anticipate development of precision torque sensors utilizing torsional pendulums that can support sensitivities below 10−19Nm/√Hz, while the motion of the pendulums are dominated by quantum radiation pressure noise at sub-microwatts of incoming laser power. These developments will provide horizons for experiments at the interface of quantum mechanics and gravity.},
  author       = {Agafonova, Sofya and Mishra, Umang and Diorico, Fritz R and Hosten, Onur},
  issn         = {2643-1564},
  journal      = {Physical Review Research},
  number       = {1},
  publisher    = {American Physical Society},
  title        = {{Zigzag optical cavity for sensing and controlling torsional motion}},
  doi          = {10.1103/physrevresearch.6.013141},
  volume       = {6},
  year         = {2024},
}

@article{14749,
  abstract     = {We unveil a powerful method for the stabilization of laser injection locking based on sensing variations in the output beam ellipticity of an optically seeded laser. The effect arises due to an interference between the seeding beam and the injected laser output. We demonstrate the method for a commercial semiconductor laser without the need for any internal changes to the readily operational injection locked laser system that was used. The method can also be used to increase the mode-hop free tuning range of lasers, and has the potential to fill a void in the low-noise laser industry.},
  author       = {Mishra, Umang and Li, Vyacheslav and Wald, Sebastian and Agafonova, Sofya and Diorico, Fritz R and Hosten, Onur},
  issn         = {1539-4794},
  journal      = {Optics Letters},
  keywords     = {Atomic and Molecular Physics, and Optics},
  number       = {15},
  pages        = {3973--3976},
  publisher    = {Optica Publishing Group},
  title        = {{Monitoring and active stabilization of laser injection locking using beam ellipticity}},
  doi          = {10.1364/ol.495553},
  volume       = {48},
  year         = {2023},
}

@article{14759,
  abstract     = {Proper operation of electro-optic I/Q modulators relies on precise adjustment and control of the relative phase biases between the modulator’s internal interferometer arms. We present an all-analog phase bias locking scheme where error signals are obtained from the beat between the optical carrier and optical tones generated by an auxiliary 2 MHz 𝑅𝐹 tone to lock the phases of all three involved interferometers for operation up to 10 GHz. With the developed method, we demonstrate an I/Q modulator in carrier-suppressed single-sideband mode, where the suppressed carrier and sideband are locked at optical power levels <−27dB
 relative to the transmitted sideband. We describe a simple analytical model for calculating the error signals and detail the implementation of the electronic circuitry for the implementation of the method.},
  author       = {Wald, Sebastian and Diorico, Fritz R and Hosten, Onur},
  issn         = {2155-3165},
  journal      = {Applied Optics},
  keywords     = {Atomic and Molecular Physics, and Optics, Engineering (miscellaneous), Electrical and Electronic Engineering},
  number       = {1},
  pages        = {1--7},
  publisher    = {Optica Publishing Group},
  title        = {{Analog stabilization of an electro-optic I/Q modulator with an auxiliary modulation tone}},
  doi          = {10.1364/ao.474118},
  volume       = {62},
  year         = {2023},
}

@article{11438,
  abstract     = {Lasers with well-controlled relative frequencies are indispensable for many applications in science and technology. We present a frequency-offset locking method for lasers based on beat-frequency discrimination utilizing hybrid electronic LC filters. The method is specifically designed for decoupling the tightness of the lock from the broadness of its capture range. The presented demonstration locks two free-running diode lasers at 780 nm with a 5.5-GHz offset. It displays an offset frequency instability below 55 Hz for time scales in excess of 1000 s and a minimum of 12 Hz at 10-s averaging. The performance is complemented with a 190-MHz lock-capture range, a tuning range of up to 1 GHz, and a frequency ramp agility of 200kHz/μs.},
  author       = {Li, Vyacheslav and Diorico, Fritz R and Hosten, Onur},
  issn         = {2331-7019},
  journal      = {Physical Review Applied},
  keywords     = {General Physics and Astronomy},
  number       = {5},
  publisher    = {American Physical Society},
  title        = {{Laser frequency-offset locking at 10-Hz-level instability using hybrid electronic filters}},
  doi          = {10.1103/physrevapplied.17.054031},
  volume       = {17},
  year         = {2022},
}