Pith. sign in

REVIEW 3 major objections 5 minor 34 references

Dual-Wavelength Brillouin Lasers as compact Opto-Terahertz References for Low-Noise Microwave Synthesis

T0 review · 3 major / 5 minor · reviewed 2026-08-07 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Pith's one-line read A 300 GHz dual-wavelength Brillouin laser divided by a single electro-optic phase modulator yields a 10 GHz signal with -170 dBc/Hz phase noise at 10 MHz offset.

desk verdict The 300 GHz eOFD demonstration is real, directly measured, and worth a serious referee; the 3.33 THz projection is where the uncorrelated-noise assumption makes the record claim soft. read the letter →

arxiv 2505.21416 v1 pith:2XN6DRFB submitted 2025-05-27 physics.optics

Scott C. Egbert , James Greenberg , Brendan M. Heffernan , William F. McGrew , Antoine Rolland This is my paper · ORCID
classification physics.optics
keywords dual-wavelengthBrillouinlaserelectro-opticfrequencydivisionphasenoisemicrowavesynthesisopto-terahertzreferenceoptical-RFheterodyne300GHz10signal
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper demonstrates that a 20-liter, dual-wavelength Brillouin laser with a 300 GHz optical spacing can serve as the opto-terahertz reference for electro-optic frequency division (eOFD), producing a 10 GHz microwave signal with phase noise of -130 dBc/Hz at 1 kHz, -150 dBc/Hz at 10 kHz, and -170 dBc/Hz at 10 MHz. The key simplification is that the moderate 300 GHz span can be bridged by a single EO phase modulator, avoiding cascaded modulators, pulse compression, and nonlinear fiber while preserving high optical signal-to-noise ratio. The authors also introduce a fiber-delay-free optical-RF heterodyne method to measure the phase noise of a 3.33 THz DWBL and project that dividing it to 10 GHz could push noise below the thermal white phase noise floor. If correct, this shows low-noise microwave synthesis can be made compact and field-deployable while matching the best laboratory OFD systems.

What carries the argument

The central mechanism is electro-optic frequency division (eOFD): a dual-wavelength Brillouin laser emits two optical lines separated by $\Delta\nu$; a single electro-optic phase modulator driven at $f_{\mu w}$ generates sidebands from both lines; a target sideband pair beats at $f_{IF}=|\Delta\nu-(m+n)f_{\mu w}|$, and a phase-locked loop forces $f_{\mu w}=\Delta\nu/(m+n)$ so the microwave oscillator inherits the optical spacing divided by $(m+n)$. The phase-noise suppression factor $(m+n)^{-2}$ applies to the optical reference, the lock reference, and loop noise, but not to amplifier noise unless the output is tapped after the high-power amplifier; placing the tap after the HPA puts that noise inside the loop and cancels it. A supporting identity is the Brillouin-laser Schawlow-Townes floor, set by thermally populated phonon modes rather than spontaneous emission, giving $S_{\phi}^{\mathrm{ST}}(f)\propto f^{-2}$ in Eq. (7). The paper's measurement tool is the optical-RF heterodyne technique, where two DWBLs are mixed on one photodetector and their intermediate-frequency beatnotes are electrically mixed to yield $\phi_{\mathrm{mix}}(t)=\phi_{\Delta\nu}(t)-\phi_{\Delta\nu'}(t)$, so the measured PSD is the sum of the two sources' PSDs.

What would settle it

Measure two 3.33 THz DWBLs with deliberately shared acoustic and thermal environments, compare the mixed phase-noise PSD with the sum of individually measured PSDs, and check for common-mode suppression; if the mixed PSD drops below the individual sum when the cavities are co-located, the uncorrelated-noise assumption fails and the projected 10 GHz performance is too optimistic.

Watch

Extended reading notes

Core claim

The central claim is that electro-optic frequency division of a low-noise opto-terahertz reference does not require multi-THz optical spans: a 300 GHz dual-wavelength Brillouin laser provides enough stability that a single phase modulator can bridge the gap with high optical SNR (about 60 dB) and an IF beatnote SNR of 84 dB in a 50 kHz resolution bandwidth, allowing the 10 GHz dielectric resonator oscillator to be phase-locked to the reference. The measured 10 GHz output reaches -130 dBc/Hz at 1 kHz, -150 dBc/Hz at 10 kHz, and -170 dBc/Hz at 10 MHz, comparable to traditional eOFD systems with much larger spans. The paper further argues that tapping the output after the high-power amplifier places amplifier phase noise inside the loop and cancels it, at the cost of imprinting amplifier amplitude noise on the output. A distinct result is the fiber-delay-free optical-RF heterodyne technique, which measures the sum of the phase-noise PSDs of two DWBLs, is validated at 300 GHz against direct millimeter-wave detection, and is then applied at 3.33 THz.

Load-bearing premise

The projection of 10 GHz phase noise from the 3.33 THz DWBL assumes that the phase noises of the two separate Brillouin fiber cavities are completely uncorrelated, and the validation of the heterodyne method at 300 GHz covers only 10 Hz to 10 kHz because the direct millimeter-wave mixer noise floor takes over above that.

Editorial extensions

If this is right

  • A 300 GHz eOFD architecture using a single EOM and single HPA eliminates the need for self-referenced combs, cascaded modulators, pulse compression, and nonlinear fiber while matching state-of-the-art 10 GHz phase noise.
  • Tapping the 10 GHz output after the HPA cancels amplifier phase noise but raises amplitude noise by about 14 dB at 10 kHz, a tradeoff designers must weigh for radar and analog photonic links versus metrology and communications.
  • The fiber-delay-free optical-RF heterodyne technique enables phase-noise characterization of multi-THz opto-terahertz references where photodetectors and mixers are unavailable, and it agrees with direct millimeter-wave measurements from 10 Hz to 10 kHz.
  • At offsets below 500 Hz, the 300 GHz, 3.33 THz, and optical references yield essentially identical phase noise when scaled to 10 GHz, so a more complex optical reference offers no low-frequency advantage.
  • Projected division of the measured 3.33 THz DWBL to 10 GHz would suppress noise by a factor of $(m+n)^2$ relative to the 300 GHz case and could fall below the thermal white phase noise floor beyond 100 kHz, contingent on generating and detecting a high-SNR EO comb spanning 3.33 THz.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the uncorrelated-noise assumption holds, the optical-RF heterodyne technique could be used to screen candidate opto-terahertz references, such as microresonator combs or molecular-stabilized sources, before building a full eOFD chain.
  • The 20-liter volume is dominated by the fiber spool and thermal packaging, suggesting that with integrated low-$V_\pi$ modulators and Kerr microresonator combs, the whole synthesizer could move toward chip-scale dimensions.
  • The amplitude-noise tradeoff identified for HPA placement suggests that a dual-tap or feedforward design could separate phase and amplitude noise paths, potentially optimizing both simultaneously; the paper notes feedforward only as a servo-bump remedy.
  • Because the Brillouin Schawlow-Townes floor is set by thermally populated phonons, cooling the fiber spool could lower the fundamental noise floor, an avenue the paper does not explore.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. This manuscript demonstrates electro-optic frequency division (eOFD) of a 300 GHz dual-wavelength Brillouin laser (DWBL) to synthesize a 10 GHz signal, using a single electro-optic phase modulator and a phase-locked dielectric resonator oscillator. The measured out-of-loop phase noise of the 10 GHz output is reported as -130 dBc/Hz at 1 kHz, -150 dBc/Hz at 10 kHz, and -170 dBc/Hz at 10 MHz. The paper also characterizes a 3.33 THz DWBL with a fiber-delay-free optical-RF heterodyne technique, validates this technique at 300 GHz against a direct millimeter-wave measurement over 10 Hz-10 kHz, and projects the 10 GHz phase noise that would result from dividing the 3.33 THz reference. The central claim is that the 300 GHz architecture drastically simplifies eOFD while preserving state-of-the-art phase noise, and that the same DWBL platform can be scaled to multi-terahertz spacings.

Significance. If the central measurements are correct, the 300 GHz eOFD demonstration is a significant practical advance: it removes cascaded modulators, pulse compression, and nonlinear fiber from the eOFD chain, and the out-of-loop cross-correlation phase noise measurement directly supports the reported 10 GHz performance. The post-HPA tap analysis in Section 3.4, including the amplitude-noise tradeoff, is a useful design contribution. The optical-RF heterodyne technique is a promising new characterization tool for multi-terahertz oscillators, and the 300 GHz validation against a direct millimeter-wave measurement is a strong check of the measurement chain. However, the 3.33 THz projection and the associated 'record' claim rest on an uncorrelated-noise assumption that the validation does not test, so the scalability narrative needs qualification or additional evidence.

major comments (3)
  1. [§4.1, Eq. (12)] The conversion from the measured pair-difference spectrum S_phi,mix(f) to a single-DWBL phase noise assumes that S_phi,Delta-nu(f) and S_phi,Delta-nu'(f) are uncorrelated. The 300 GHz validation in Fig. 5(c) compares the optical-RF heterodyne signal with a direct UTC-PD/mm-wave measurement of the same pair-difference observable; it therefore validates the RF detection chain but cannot test the 3 dB split. If the two fiber cavities share acoustic or thermal noise, common-mode rejection reduces the measured sum and the inferred single-DWBL phase noise is optimistically low. This directly affects the 3.33 THz trace in Fig. 5(c), the projected 10 GHz curve in Fig. 6, and the conclusion that a 3.33 THz reference would enable record-breaking microwave synthesis. Please provide a quantitative correlation test (e.g., a cross-spectrum between the two DWBLs with independent detection chains) or explicitly label the 3.33 THz single-source estimate and its 10 GHz projection as a lower bound on the true phase noise (i.e., an optimistic estimate) pending such a test.
  2. [§5, Fig. 6, and §6] The projected 10 GHz performance of the 3.33 THz reference, including the statement that the trace 'dips below the thermal white phase noise floor,' is obtained by scaling a measured pair-difference spectrum by 1/(333)^2 and assumes an ideal division scheme that the authors state is not yet achievable with a single EOM. The conclusion that extending the span to 3.33 THz 'holds the potential for record-breaking phase noise performance' is therefore a projection, not a demonstrated result. Please separate this projection into a clearly labeled outlook subsection and temper the language in the abstract and conclusion so that readers do not mistake the projected curve for a measured 10 GHz signal.
  3. [§3.3, Eq. (7), and Fig. 3] The claim that the measured phase noise floor is in 'excellent agreement' with the Schawlow-Townes expression is not supported by any numerical evaluation of Eq. (7); no values for tau, tau_ex, P, n, or v_a are given, and no uncertainty is attached to the measured floor. Please provide the calculation with parameter values or soften the claim to 'consistent with the expected scale' until the comparison is quantitative.
minor comments (5)
  1. [§3.2, Fig. 2] The phase noise traces are shown without confidence intervals or repeated-measurement spread; given the state-of-the-art performance claims, please specify the measurement uncertainty, the number of cross-correlation averages, and the noise floor of the SSA-X measurement.
  2. [§4.1] The conditions that make the two DWBLs 'nearly identical' are not defined; please specify the optical frequency offsets, output powers, and cavity lengths, since these affect the validity of Eq. (12).
  3. [§4.2, Fig. 5(c)] The caption describes the 3.33 THz result as 'a record performance at multi-terahertz frequencies' without citing prior work or defining the comparison set; either cite specific comparators or call it a first demonstration of this measurement technique.
  4. [§3.1, Fig. 1(b)] The optical spectra would be much clearer with a calibrated frequency axis and a marker indicating the 300 GHz span; the current description is qualitative.
  5. [§3.3, Eq. (7)] Eq. (7) is dimensionally unfamiliar as written; please confirm the units of the prefactor and state explicitly which quantities are to be taken in SI units, since the numerical agreement claimed later depends on this.

Circularity Check

0 steps flagged · score 2.0 of 10

No load-bearing circularity: the 300 GHz eOFD phase-noise result is an out-of-loop measurement, the Schawlow-Townes floor uses an external formula, and the 3.33 THz projection is explicitly labelled hypothetical; only a minor background self-citation and an explicit uncorrelated-noise assumption prevent a zero score.

full rationale

The paper's central 10 GHz result (Section 3.2, Fig. 2) is independently measured with a Keysight SSA-X cross-correlation analyzer on the actual synthesized output, not generated from a fitted model. The Schawlow-Townes comparison in Section 3.3 uses Eq. (7) from Ref. [27], an external published formula, and the agreement is presented as a validation rather than a fit; no parameters are tuned to the measured noise in a way that would make the floor self-fulfilling. The eOFD transfer function in Eq. (5) is a conventional PLL noise propagation expression and is not fit to the measured data. The optical-RF heterodyne technique in Section 4 is validated against a direct UTC-PD/mm-wave measurement of the same two-DWBL pair-difference quantity (Fig. 5(c)) over 10 Hz to 10 kHz, so the measurement chain is independently anchored. This validation does not test the Eq. (12) assumption that the two DWBL phase noises are uncorrelated, which is an explicit assumption and a correctness risk for the 3.33 THz projection, not a circular derivation. The 3.33 THz-to-10 GHz curves in Fig. 6 are clearly labeled 'yet-to-be-implemented' and hypothetical, and the conclusion describes them as potential, not demonstrated. Self-citations to Ref. [24] provide prior DWBL design and a comparative measurement, but the present 20 L system and the eOFD stabilization are newly measured here; that citation is background support, not the load-bearing derivation. No uniqueness theorem from the authors is invoked to force the architecture, and the EO-comb/eOFD framework is credited to external Ref. [19]. The 'only delay-line-free technique' statement is a scoping claim, not a circular premise. Overall, no step in the derivation reduces, by construction, to its own input.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

The central 10 GHz demonstration rests on direct measurement rather than fitted parameters; no free parameters are introduced. The projections to 3.33 THz and the noise floor comparison rely on the Schawlow-Townes formula and the uncorrelated-DWBL assumption, which are domain assumptions. No new entities are postulated.

assumptions (4)
  • standard math Phase noise PSDs of uncorrelated noise sources add in quadrature.
    Used throughout Section 2 and Section 4.1 to sum laser, reference, loop, and HPA noise contributions. This is standard for independent stochastic processes.
  • domain assumption The two DWBLs used in the optical-RF heterodyne measurement have uncorrelated phase noise.
    Section 4.1, Eq. (12). The authors state 'assuming no correlation'. This is load-bearing for the 3.33 THz phase noise characterization and the projected 10 GHz performance in Fig. 6. If the two fiber cavities share acoustic or thermal noise, the inferred single-DWBL noise would be underestimated.
  • domain assumption The Schawlow-Townes formula for a single-wavelength Brillouin laser (Eq. 7, from Ref. [27]) applies, with a factor of 2 for a dual-wavelength laser.
    Section 3.3. Used to identify the fundamental noise floor and to claim agreement with the measured floor. The factor 2 is asserted, not derived.
  • domain assumption Common-mode rejection of fiber cavity length fluctuations is a factor of (3.33/0.3)^2 less effective than at 300 GHz.
    Section 4.2. Used to explain elevated phase noise of the 3.33 THz DWBL. This scaling is stated without derivation.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Dual-Wavelength Brillouin Lasers as compact Opto-Terahertz References for Low-Noise Microwave Synthesis." pith.science (2026). https://pith.science/paper/2XN6DRFB

@misc{pith2026250521416,
  author       = {Pith},
  title        = {Pith review of: Dual-Wavelength Brillouin Lasers as compact Opto-Terahertz References for Low-Noise Microwave Synthesis},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2XN6DRFB}},
  note         = {Machine review of arXiv:2505.21416}
}
read the original abstract

Compact, ultra-low phase noise 10 GHz signals are essential for modern radar, coherent communications, and time-frequency metrology, especially with rising demands for additional spectral purity and portability. Optical frequency division (OFD) of ultra-stable optical references produce the lowest noise microwaves, but typically rely on ultra-low-expansion cavities, self-referenced frequency combs, pulse interleaving, and high-end photodetectors. In contrast, electro-optic frequency division (eOFD) offers a streamlined alternative in which an electro-optic (EO) comb is generated from a microwave source and stabilized to an optically carried terahertz (opto-terahertz) reference. eOFD has already demonstrated comparable phase noise to OFD at 10, 20, and 40 GHz when using division ratios from references spanning over 1 THz, requiring broad EO comb spectra to bridge between optical signals. Generating such broad spectra often demands complex techniques such as cascaded modulators, pulse compression, and nonlinear fiber. We demonstrate a compact, low-noise 300 GHz opto-terahertz reference utilizing a dual-wavelength Brillouin laser within a total system volume of 20 liters. The 300 GHz phase noise of this system is transferred to a 10 GHz dielectric resonant oscillator via eOFD using a simple architecture that could be miniaturized. The resulting microwave signal achieves phase noise levels of -130 dBc/Hz at 1 kHz, -150 dBc/Hz at 10 kHz, and -170 dBc/Hz at 10 MHz. This architecture drastically simplifies eOFD while maintaining state-of-the-art phase noise.

Figures

Figures reproduced from arXiv: 2505.21416 by the authors.

Figure 1
Figure 1. Setup used for eOFD using a DWBL. (a) Schematic of the full eOFD system and photo of the DWBL used. (b) Optical spectra: optically amplified DWBL output (red), EO-modulated output (blue), and filtered sidebands (black). (c) RF spectrum of the detected EO comb beatnote (RBW: 50 kHz). A key design detail is the placement of the 10 GHz output tap after the HPA, which minimizes added phase noise from the RF drive chain.… view at source ↗
Figure 2
Figure 2. One-sided phase noise PSD of the 10 GHz output derived from the DWBL using [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Breakdown of phase noise contributions in the eOFD-stabilized DRO system. [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figures from the paper (3 more)
Figure 4
Figure 4. Figure 4: One-sided amplitude noise PSD of the 10 GHz output of the DRO as measured [PITH_FULL_IMAGE:figures/full_fig_p008_4.png]
Figure 5
Figure 5. Figure 5: Comparison of heterodyne DWBL characterization techniques. ( [PITH_FULL_IMAGE:figures/full_fig_p010_5.png]
Figure 6
Figure 6. Figure 6: Comparison of three OFD techniques for generating a 10 GHz source. 300 GHz [PITH_FULL_IMAGE:figures/full_fig_p011_6.png]

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

34 extracted references · 33 canonical work pages

  1. [1]

    A fully photonics-based coherent radar system,

    P. Ghelfi, F. Laghezza, F. Scotti,et al., “A fully photonics-based coherent radar system,” Nature507, 341–345 (2014)

    work page 2014

  2. [2]

    Optical clocks at sea,

    J. D. Roslund, A. Cingöz, W. D. Lunden,et al., “Optical clocks at sea,” Nature628, 736–740 (2024)

    2024

  3. [3]

    Optical clocks at sea,

    E. D. Caldwell, L. C. Sinclair, J.-D. Deschenes,et al., “Optical clocks at sea,” APL Photonics9(2024)

    work page 2024

  4. [4]

    A vlbi experiment using a remote atomic clock via a coherent fibre link,

    C. Clivati, R. Ambrosini, T. Artz,et al., “A vlbi experiment using a remote atomic clock via a coherent fibre link,” Sci. Reports7(2017)

    work page 2017

  5. [5]

    Thz communications: Paving the way towards wireless tbps,

    T. Kürner, D. M. Mittleman, and T. Nagatsuma, “Thz communications: Paving the way towards wireless tbps,” Springer Ser. Opt. Sci.234(2016)

    work page 2016

  6. [6]

    C. H. Townes and A. L. Schawlow,Microwave Spectroscopy(Dover Publications, New York, 1975)

    work page 1975

  7. [7]

    Enantiomer-specific detection of chiral molecules via microwave spectroscopy,

    D. Patterson, M. Schnell, and J. M. Doyle, “Enantiomer-specific detection of chiral molecules via microwave spectroscopy,” Nature497, 475–477 (2013)

    work page 2013

  8. [8]

    Rubiola,Phase Noise and Frequency Stability in Oscillators(Cambridge University Press, Cambridge, UK, 2008)

    E. Rubiola,Phase Noise and Frequency Stability in Oscillators(Cambridge University Press, Cambridge, UK, 2008)

    work page 2008

Show all 34 references
  1. [9]

    Ultra-low-noise microwave extraction from fiber-based optical frequency comb,

    J. Millo, R. Boudot, M. Lours,et al., “Ultra-low-noise microwave extraction from fiber-based optical frequency comb,” Opt. letters34, 3707–3709 (2009)

    2009

  2. [10]

    Generationofultrastablemicrowavesviaopticalfrequencydivision,

    T.M.Fortier,M.S.Kirchner,F.Quinlan,etal.,“Generationofultrastablemicrowavesviaopticalfrequencydivision,” Nat. photonics5, 425–429 (2011)

    2011

  3. [11]

    Optical-fiber pulse rate multiplier for ultralow phase-noise signal generation,

    A. Haboucha, W. Zhang, T. Li,et al., “Optical-fiber pulse rate multiplier for ultralow phase-noise signal generation,” Opt. letters36, 3654–3656 (2011)

    2011

  4. [12]

    Optical amplification and pulse interleaving for low-noise photonic microwave generation,

    F. Quinlan, F. N. Baynes, T. M. Fortier,et al., “Optical amplification and pulse interleaving for low-noise photonic microwave generation,” Opt. letters39, 1581–1584 (2014)

    2014

  5. [13]

    Ultra-low phase noise microwave generation with a free-running monolithic femtosecond laser,

    M. Kalubovilage, M. Endo, and T. R. Schibli, “Ultra-low phase noise microwave generation with a free-running monolithic femtosecond laser,” Opt. Express28, 25400–25409 (2020)

    2020

  6. [14]

    Exploiting shot noise correlations in the photodetection of ultrashort optical pulse trains,

    F. Quinlan, T. M. Fortier, H. Jiang,et al., “Exploiting shot noise correlations in the photodetection of ultrashort optical pulse trains,” Nat. Photonics7, 290–293 (2013)

    2013

  7. [15]

    Photonic microwave signals with zeptosecond-level absolute timing noise,

    X. Xie, R. Bouchand, D. Nicolodi,et al., “Photonic microwave signals with zeptosecond-level absolute timing noise,” nature photonics11, 44–47 (2017)

    2017

  8. [16]

    Microwavegenerationwithlowresidualphasenoise from a femtosecond fiber laser with an intracavity electro-optic modulator,

    W.C.Swann,E.Baumann,F.R.Giorgetta,andN.R.Newbury,“Microwavegenerationwithlowresidualphasenoise from a femtosecond fiber laser with an intracavity electro-optic modulator,” Opt. express19, 24387–24395 (2011)

    2011

  9. [17]

    Optically referenced 300 ghz millimetre-wave oscillator,

    T. Tetsumoto, T. Nagatsuma, M. E. Fermann,et al., “Optically referenced 300 ghz millimetre-wave oscillator,” Nat. Photonics15, 516–522 (2021)

    2021

  10. [18]

    Low-noise microwave generation with an air-gap optical reference cavity,

    Y. Liu, D. Lee, T. Nakamura,et al., “Low-noise microwave generation with an air-gap optical reference cavity,” APL Photonics9(2024)

    2024

  11. [19]

    Electro-opticalfrequencydivisionandstablemicrowavesynthesis,

    J.Li,X.Yi,H.Lee,etal.,“Electro-opticalfrequencydivisionandstablemicrowavesynthesis,”Science345,309–313 (2014)

    2014

  12. [20]

    Small-sized, ultra-low phase noise photonic microwave oscillators at x-ka bands,

    J. Li and K. Vahala, “Small-sized, ultra-low phase noise photonic microwave oscillators at x-ka bands,” Optica10, 33–34 (2023)

    2023

  13. [21]

    Tunable x-band opto-electronic synthesizer with ultralow phase noise,

    I. Kudelin, P. Shirmohammadi, W. Groman,et al., “Tunable x-band opto-electronic synthesizer with ultralow phase noise,” arXiv preprint arXiv:2404.00136 (2024)

    2024 arXiv

  14. [22]

    Highly coherent two-color laser with stability below 3e-17 at 1 second,

    B. He, J. Yang, F. Meng,et al., “Highly coherent two-color laser with stability below 3e-17 at 1 second,” arXiv preprint arXiv:2411.19703 (2024)

    2024 arXiv

  15. [23]

    Ultralow noise microwave synthesis via difference frequency division of a brillouin resonator,

    W. Loh, D. Gray, R. Irion,et al., “Ultralow noise microwave synthesis via difference frequency division of a brillouin resonator,” Optica11, 492–497 (2024)

    2024

  16. [24]

    Brillouin Laser-Driven Terahertz Oscillator up to 3 THz with Femtosecond-Level Timing Jitter,

    B. M. Heffernan, J. Greenberg, T. Hori,et al., “Brillouin Laser-Driven Terahertz Oscillator up to 3 THz with Femtosecond-Level Timing Jitter,” Nat. Photonics18, 1263–1268 (2024). Publisher: Nature Publishing Group

    2024

  17. [25]

    Palm-Sized, Vibration-Insensitive, and Vacuum-Free All-Fiber-Photonic Module for 10-14-Level Stabilization of CW Lasers and Frequency Combs,

    I. Jeon, C. Ahn, C. Kim,et al., “Palm-Sized, Vibration-Insensitive, and Vacuum-Free All-Fiber-Photonic Module for 10-14-Level Stabilization of CW Lasers and Frequency Combs,” APL Photonics8, 120804 (2023)

    2023

  18. [26]

    Advanced noise reduction techniques for ultra-low phase noise optical-to- microwave division with femtosecond fiber combs,

    W. Zhang, Z. Xu, M. Lours,et al., “Advanced noise reduction techniques for ultra-low phase noise optical-to- microwave division with femtosecond fiber combs,” IEEE transactions on ultrasonics, ferroelectrics, frequency control58, 900–908 (2011)

    2011

  19. [27]

    Microwave synthesizer using an on-chip brillouin oscillator,

    J. Li, H. Lee, T. Chen, and K. J. Vahala, “Microwave synthesizer using an on-chip brillouin oscillator,” Nat. Commun. (2013)

    2013

  20. [28]

    Linewidth narrowing in Brillouin lasers: Theoretical analysis,

    A. Debut, S. Randoux, and J. Zemmouri, “Linewidth narrowing in Brillouin lasers: Theoretical analysis,” Phys. Rev. A62, 023803 (2000)

    2000

  21. [29]

    A photonic frequency discriminator based on a two wavelength delayed self-heterodyne interferometer for low phase noise tunable micro/mm wave synthesis,

    N. Kuse and M. Fermann, “A photonic frequency discriminator based on a two wavelength delayed self-heterodyne interferometer for low phase noise tunable micro/mm wave synthesis,” Sci. reports8, 13719 (2018)

    2018

  22. [30]

    Spiral resonator referenced on-chip low noise microwave generation,

    L. Cheng, M. Zhao, Y. He,et al., “Spiral resonator referenced on-chip low noise microwave generation,” arXiv preprint arXiv:2502.13470 (2025)

    2025 arXiv

  23. [31]

    Kerr optical frequency division with integrated photonics for stable microwave and mmwave generation,

    S. Sun, M. W. Harrington, F. Tabatabaei,et al., “Kerr optical frequency division with integrated photonics for stable microwave and mmwave generation,” arXiv preprint arXiv:2402.11772 (2024)

    2024 arXiv

  24. [32]

    Terahertz microcomb oscillator stabilized by molecular rotation,

    J. Greenberg, B. M. Heffernan, and A. Rolland, “Terahertz microcomb oscillator stabilized by molecular rotation,” APL Photonics9(2024)

    2024

  25. [33]

    Dual wavelength brillouin laser terahertz source stabilized to carbonyl sulfide rotational transition,

    J. Greenberg, B. M. Heffernan, W. F. McGrew,et al., “Dual wavelength brillouin laser terahertz source stabilized to carbonyl sulfide rotational transition,” Nat. Commun.16, 2411 (2025)

    2025

  26. [34]

    Terahertz molecular frequency references: theoretical analysis of optimal instability,

    W. McGrew, J. Greenberg, K. Nose,et al., “Terahertz molecular frequency references: theoretical analysis of optimal instability,” arXiv preprint arXiv:2502.13274 (2025)

    2025 arXiv

Pith tools

Reviewed August 7, 2026 · model on record in the stance chip above.