---
title: 'Dual-Comb LIDAR: Fundamentals & Advances'
url: https://www.emergentmind.com/topics/dual-comb-lidar
type: topic
---

# Dual-Comb LIDAR: Fundamentals & Advances

Searching arXiv for recent papers on dual-comb LiDAR and related implementations.
Dual-comb LIDAR is a ranging modality in which two optical frequency combs with slightly different repetition rates are interfered so that optical delay is mapped into a radio-frequency interferogram, enabling absolute distance measurement, high update rates, and precision that can approach interferometric regimes. In the implementations reported across fiber, solid-state, electro-optic, and microresonator platforms, one comb typically serves as a probe or signal and the other as a local oscillator, while the small repetition-rate offset $\Delta f_{\rm rep}$ sets the interferogram repetition period and, depending on architecture, the update rate, aliasing behavior, and non-ambiguity range. Reported variants include heterodyne phase-slope ranging, dead-zone-free linear optical sampling, dual-comb FMCW, differential-absorption lidar, and two-photon cross-correlation schemes that are carrier-phase-insensitive and avoid near-gigasample/s digitization [2411.05585], [1707.05969], [2101.03952], [2406.18208], [2108.10146], [2603.07741].

## 1. Fundamental operating principle

In dual-comb ranging, two optical frequency combs have repetition rates $f_{\rm rep,1}=f_{\rm rep}$ and $f_{\rm rep,2}=f_{\rm rep}+\Delta f_{\rm rep}$, and their interference on a photodetector produces a multi-heterodyne radio-frequency comb whose lines are separated by $\Delta f_{\rm rep}$. A representative expression for the photocurrent is
$$
I(t)\propto \Re\bigl\{E_1(t)\,E_2^*(t)\bigr\}
\;\approx\;\sum_{m}B_{m}\,\exp\!\bigl[i\,(2\pi\,m\,\Delta f_{\rm rep}\,t + \phi_{m})\bigr],
$$
with each RF comb line carrying phase information related to optical delay [2411.05585]. In probe/LO language, if one comb interrogates a target and the return is heterodyned against the second comb, the resulting interferogram or RF beat phases encode the round-trip path length.

Several equivalent ranging formalisms appear in the literature. In time-of-flight form,
$$
d=\frac{c\,\Delta t}{2},
$$
with $\Delta t$ the round-trip delay [2411.05585]. In phase-based dual-comb ranging, a phase shift $\Delta\phi$ at a beat frequency can be converted into distance through
$$
d=\frac{c\,\Delta\phi}{2\pi\,\Delta f_{r}},
$$
as used in single-tone or phase-unwrapped formulations [2504.09659]. In multi-line synthetic-wavelength interferometry, one fits the phase variation across comb index to recover distance from the slope, exploiting the fact that the phase of line $m$ varies linearly with $m$ and with path length [1707.05969], [2202.05644].

The same general principle admits distinct detection modalities. Conventional heterodyne implementations detect RF combs or interferograms directly on fast photodiodes and usually process them with FFTs, Hilbert transforms, phase fitting, or center-of-mass delay extraction [2411.05585], [2504.09659]. Two-photon dual-comb LIDAR instead uses a nonlinear detector so that overlap of sub-picosecond probe and LO pulses generates electrical cross-correlation pulses. Because the two-photon response depends on pulse overlap rather than optical carrier phase, this detection is described as carrier-phase-insensitive and is not constrained by the conventional RF aliasing condition [2108.10146], [2603.07741].

A recurring architectural distinction is between dual-comb systems built from two separate combs and single-cavity dual-comb lasers. The latter generate two combs in a common cavity, often by polarization multiplexing or bidirectional propagation, so environmental perturbations act as common-mode fluctuations. This suppresses differential timing noise and enhances mutual coherence, which is especially valuable for long interferogram acquisition and dead-zone-free ranging [2509.01077], [2411.05585], [2508.03476].

## 2. Distance ambiguity, update rate, and precision trade-offs

A central design parameter is the non-ambiguity range. In formulations based directly on the repetition-rate offset, the maximum unambiguous distance is commonly written as
$$
D_{\max}=\frac{c}{2\,\Delta f_{\rm rep}},
$$
or equivalently as $\Delta z_{\max}=c/(2\,\Delta f_r)$ in axial-profiling notation [2509.01077], [2504.09659]. The implication is immediate: reducing $\Delta f_{\rm rep}$ increases non-ambiguity range but slows the interferogram repetition rate. Zhu et al. reported that varying $\Delta f_{\rm rep}$ from $\simeq210\,\mathrm{Hz}$ down to $\simeq85\,\mathrm{Hz}$ changes $D_{\max}$ from $\simeq710\,\mathrm{km}$ to $\simeq1.8\times10^6\,\mathrm{m}$ $(1\,800\,\mathrm{km})$ [2509.01077].

In other architectures, ambiguity is tied instead to the comb repetition rate or the synthetic wavelength associated with RF line spacing. The analysis of repetition-rate-limited dual-comb ranging gives
$$
NAR=\frac{c}{2\,f_{\rm rep}},
$$
where increasing $f_{\rm rep}$ improves precision but shortens the non-ambiguity range [2202.05644]. In integrated dissipative-Kerr-soliton systems, the synthetic wavelength is $\Lambda=c/\Delta f$, and the ambiguity interval is reported as $\Lambda\approx3.07\,\mathrm{m}$ for $\Delta f\approx97.7\,\mathrm{MHz}$ [1707.05969]. In FMCW dual-soliton microcomb ranging, the chirp period rather than the RF offset sets the unambiguous range through $cT/2=1.5\,\mathrm{km}$ for $T=10\,\mu\mathrm{s}$ [2101.03952].

Update rate is usually equal to $\Delta f_{\rm rep}$ or its inverse relation through one interferogram per $1/\Delta f_{\rm rep}$. Camenzind et al. used $\Delta f_{\rm rep}=5.06\,\mathrm{kHz}$, corresponding to a new distance and phase update every $\approx198\,\mu\mathrm{s}$ [2411.05585]. In micromachining metrology, $\Delta f_r=6.6\,\mathrm{kHz}$ gives an update time of $\approx152\,\mu\mathrm{s}$ [2504.09659]. Integrated DKS dual-comb LIDAR reached a minimum acquisition time $T_{\min}=1/\Delta f\approx10.3\,\mathrm{ns}$ and thus a maximum ranging rate of $\approx97.7\,\mathrm{MHz}$ [1707.05969]. Two-photon continuous-streaming systems reported sustained streaming at $\sim11.5\,\mathrm{kHz}$ and burst rates up to $20\,\mathrm{kHz}$ [2603.07741].

Precision depends on architecture, bandwidth, SNR, and averaging. Reported figures span several regimes. In free-space dead-zone-free dual-comb ranging, the single-shot time-of-flight precision is around $0.1\,\mu\mathrm{m}$ on a cooperative target at more than $40\,\mathrm{m}$, and interferometric use of phase improves the single-shot precision to $<20\,\mathrm{nm}$ [2411.05585]. Microresonator soliton ranging achieved $\sigma_d \simeq 284\,\mathrm{nm}$ in a single $10.3\,\mathrm{ns}$ acquisition and $12\,\mathrm{nm}$ after $14\,\mu\mathrm{s}$ averaging [1707.05969]. The electro-optic analysis of system limits reported $1.8\,\mu\mathrm{m}$ one-shot precision with $16\,\mu\mathrm{s}$ FFTs and a best Allan deviation of $372\,\mathrm{nm}$ after averaging to $1.15\,\mathrm{ms}$ [2202.05644]. In two-photon dual-comb imaging at a $40\,\mathrm{cm}$ stand-off, precisions averaged to $1.0\,\mu\mathrm{m}$ after $500\,\mathrm{ms}$, with accuracies of $9\,\mu\mathrm{m}$ to $38\,\mu\mathrm{m}$ [2603.12729].

This recurring precision–range trade-off was formalized by a performance factor in which the ratio of precision to non-ambiguity range is independent of repetition rate for a fixed comb envelope and SNR. The relation
$$
\sigma_d=\frac{2\,NAR}{\pi}\,\sigma_s
$$
captures that trade-off explicitly [2202.05644]. This suggests that improvements in comb flattening, optical bandwidth, and detection SNR can be as consequential as tuning repetition rates.

## 3. Source architectures and mutual coherence strategies

Dual-comb LIDAR has been implemented with single-cavity solid-state lasers, polarization-multiplexed and bidirectional fiber lasers, electro-optic combs, and microresonator soliton combs. Each source class imposes a different balance among coherence, tunability, repetition rate, RF bandwidth, and system complexity.

Single-cavity lasers are frequently used to exploit common-mode noise suppression. In the Yb:CaF$_2$ free-running dual-comb laser used for dead-zone-free moving-target tracking, the carrier wavelength is $\lambda_c\approx1055\,\mathrm{nm}$, the pulse repetition rate is $1.041\,\mathrm{GHz}$, and the repetition-rate difference is $5.06\,\mathrm{kHz}$ [2411.05585]. In a polarization-multiplexed Er-doped fiber ring cavity, two orthogonal states of polarization circulate with slightly different group velocities, giving a fundamental repetition rate of $\approx39.247\,\mathrm{MHz}$ and $\Delta f_{\rm rep}\approx869\,\mathrm{Hz}$, with RF beat-note SNR $>60\,\mathrm{dB}$, linewidth $\sim1.5\,\mathrm{Hz}$, and drift $\lesssim1\,\mathrm{Hz/hour}$ over long operation [2508.03476]. These reported drifts support sub-millimetre ranging in metre-scale ambiguity ranges and in-principle ambiguity lengths of hundreds of kilometres [2508.03476].

The bidirectional Lyot-filtered fiber laser of Zhu et al. represents a specific advance in repetition-rate-difference control. It uses a $7\,\mathrm{m}$ long PM fiber ring, bidirectionally pumped at $980\,\mathrm{nm}$, with a thermally controlled bidirectional Lyot filter formed by a $10\,\mathrm{cm}$ PMF segment spliced at $45^\circ$ at each end [2509.01077]. The slow and fast polarization-axis combs exhibit thermal sensitivities of $88.5\,\mathrm{Hz}/^\circ\mathrm{C}$ and $84.2\,\mathrm{Hz}/^\circ\mathrm{C}$, so the differential tuning coefficient is $k=4.4\,\mathrm{Hz}/^\circ\mathrm{C}$, corresponding to $5.0\,\mathrm{Hz}/\mathrm{nm}$ [2509.01077]. With a heater resolution of $0.1\,^\circ\mathrm{C}$, the absolute uncertainty in $\Delta f_{\rm rep}$ is $\pm0.44\,\mathrm{Hz}$, described as about $870\times$ better than a mechanical delay line [2509.01077]. The reported tuning range is from $\simeq210\,\mathrm{Hz}$ down to $\simeq85\,\mathrm{Hz}$ as temperature varies from $35^\circ\mathrm{C}$ to $62^\circ\mathrm{C}$ [2509.01077].

Microresonator-based systems occupy the opposite extreme of repetition rate. Dual DKS combs in Si$_3$N$_4$ microresonators operated at $\approx95.646\,\mathrm{GHz}$ and $\approx95.549\,\mathrm{GHz}$ with $\Delta f\approx97.7\,\mathrm{MHz}$ and an optical bandwidth of $\approx11\,\mathrm{THz}$ over about $115$ lines [1707.05969]. Crystalline MgF$_2$ multi-resonator stacks produced soliton combs with repetition rates near $12.1\,\mathrm{GHz}$ and a difference of $1.62\,\mathrm{MHz}$, yielding an RF comb span of about $300\,\mathrm{MHz}$ [1612.07044]. These high-repetition-rate combs support very high update rates and compact integration, but their ambiguity intervals are correspondingly shorter unless compensated by other techniques.

Electro-optic and chirped-comb implementations emphasize deterministic spectral structure and waveform agility. In dual-comb DIAL for greenhouse-gas and wind sensing, a single narrow-linewidth CW laser at $1572\,\mathrm{nm}$ feeds phase modulators to generate two combs with tooth spacings $2\,500\,\mathrm{MHz}$ and $2\,507.5\,\mathrm{MHz}$, i.e. $\Delta f_{\rm rep}=7.5\,\mathrm{MHz}$, using only three teeth per comb to maximize power per tooth [2406.18208]. In swept dual-soliton microcomb FMCW LiDAR, a single pump is chirped with a triangular waveform of period $10\,\mu\mathrm{s}$ and excursion $B\approx1.5$–$1.8\,\mathrm{GHz}$, generating synchronously chirped combs at $98.90\,\mathrm{GHz}$ and $99.39\,\mathrm{GHz}$ or, in a denser-comb configuration, around $35\,\mathrm{GHz}$ and $35.14\,\mathrm{GHz}$ [2101.03952].

## 4. Measurement topologies and signal processing

Dual-comb LIDAR encompasses several distinct measurement topologies. In linear optical sampling or direct heterodyne ranging, the signal comb is split between a reference and a target path and the returns are interfered with the LO comb. Camenzind et al. used a free-space transceiver with a Wollaston prism that combines orthogonally polarized combs into a common path, plus two reference reflections $R_1$ and $R_2$ separated by a fixed delay $\delta\tau\lesssim1/\Delta f_{\rm rep}$ so that at least one reference interferogram does not overlap the target interferogram [2411.05585]. Both signal combs probe the target and interchange signal/LO roles in parallel, allowing Vernier non-ambiguity-range extension [2411.05585].

Their real-time processing chain is GPU-accelerated. In each $\Delta f_{\rm rep}^{-1}\approx198\,\mu\mathrm{s}$ window, interferograms sampled at $125\,\mathrm{MS/s}$ are transferred to the GPU, frequency-shifted toward DC, converted to complex envelopes via Hilbert transform, searched for the two references and target pulse, and analyzed for center-of-mass delays and phase delays. Overlap cases are detected and corrected by subtracting the clean reference, and absolute time-of-flight and interferometric phase are unwrapped and tracked in real time. A sustained processing rate up to $7.1\,\mathrm{kHz}$ was reported, with the Hilbert transform taking about $100\,\mu\mathrm{s}$ on an RTX A5000 [2411.05585].

In industrial in-situ 3D profiling, the dual-comb beam is combined coaxially with a $1064\,\mathrm{nm}$ picosecond micromachining beam by a polarizing beam splitter, scanned through a 2D galvanometric system, and focused onto the workpiece with an $f=100\,\mathrm{mm}$ f-theta lens to a $\approx20\,\mu\mathrm{m}$ spot [2504.09659]. The back-scattered comb light is collected through the same objective and detected by a $>125\,\mathrm{MHz}$ photodiode, digitized at $250\,\mathrm{MS/s}$, then processed by FFT or Hilbert-transform methods [2504.09659]. A typical scan uses a $550\times300$ grid with $10\,\mu\mathrm{m}$ lateral spacing and five measurements per point, corresponding to $165\,000$ lateral positions and a total scan time of about $3\,\mathrm{min}$ [2504.09659].

Dual-comb FMCW departs from static multi-heterodyne ranging by sweeping both combs synchronously. For comb mode index $\mu$, the up- and down-ramp beat frequencies are
$$
f^\mathrm{u}_\mu=\mu\,\Delta f_{\rm rep}+\frac{B}{2T}\,\tau+\nu_\mu\frac{v}{c},
\qquad
f^\mathrm{d}_\mu=\mu\,\Delta f_{\rm rep}-\frac{B}{2T}\,\tau+\nu_\mu\frac{v}{c},
$$
from which both range and radial velocity are obtained per comb line [2101.03952]. The signal chain includes an optical hybrid, balanced photodiodes producing I and Q outputs, and digitization at $20\,\mathrm{GS/s}$ with $10\,\mathrm{GHz}$ bandwidth, followed by STFT and Gaussian peak fitting [2101.03952]. This architecture supports parallel ranging and velocimetry across up to $64$ spectrally dispersed optical channels and megapixel-line rates [2101.03952].

Two-photon systems use markedly simpler electronics. Probe and LO pulses overlap in a two-photon absorption detector, producing a cross-correlation pulse train at $\Delta f_{\rm rep}$ rather than GHz fringe data [2108.10146], [2603.07741]. The front-end can consist of a TPA photodiode, a $20\,\mathrm{MHz}$ current amplifier, a constant-fraction discriminator, and digital time stamping with TDCs or a microcontroller [2603.07741]. One implementation used two TI-TDC7200 time-to-digital converters with $55\,\mathrm{ps}$ resolution and a Teensy 4.0 microcontroller streaming $64$ bits per sample over USB at up to $12\,\mathrm{kSa/s}$, for a data burden below $1\,\mathrm{Mbps}$ [2603.07741]. This is the principal reason two-photon dual-comb ranging can operate continuously without near-gigasample/s acquisition.

## 5. Demonstrated application domains

The most direct application is absolute distance metrology and target tracking. The free-space dead-zone-free architecture tracked a cooperative target moved over $40\,\mathrm{m}$ and compared dual-comb results with a He–Ne reference interferometer. The residuals were below $3\,\mu\mathrm{m}$ over the tested range, while phase-enabled operation provided sub-$20\,\mathrm{nm}$ single-shot precision [2411.05585]. The same work reports real-time tracking of moving targets, with sufficiently stable free-running operation to use interferometric phase without $f_{\rm ceo}$ stabilization [2411.05585].

High-speed compact ranging is a major theme in microresonator systems. Integrated DKS dual-comb LIDAR demonstrated acquisition rates up to $97.7\,\mathrm{MHz}$, Allan deviations down to $12\,\mathrm{nm}$ at $14\,\mu\mathrm{s}$, and moving-target measurements on air-gun projectiles flying at $150\,\mathrm{m/s}$ and on a rotating disk at edge speed $160\,\mathrm{m/s}$ [1707.05969]. The reported lateral sampling on the rotating disk was about $1.6\,\mu\mathrm{m}$, and the projectile profile agreed with swept-source OCT of the recovered bullet [1707.05969]. This established dual-comb LIDAR as compatible with ultrafast motion tracking rather than only static metrology.

Parallel coherent ranging and velocimetry have been demonstrated with swept dual-soliton microcombs. The reported system delivered line-scan pixel rates of $2.8\,\mathrm{MPix/s}$ with $28$ channels in a $100\,\mathrm{GHz}$ comb and $5.6\,\mathrm{MPix/s}$ with roughly $81$ channels in a $35\,\mathrm{GHz}$ comb [2101.03952]. Range resolution was $8$–$12\,\mathrm{cm}$ in the $100\,\mathrm{GHz}$ case and $16$–$30\,\mathrm{cm}$ in the $35\,\mathrm{GHz}$ case, with a common unambiguous range of $1.5\,\mathrm{km}$ and demonstrated velocity imaging of a $162\,\mathrm{Hz}$ flywheel at $20.4\,\mathrm{m/s}$ [2101.03952]. This positions dual-comb methods within coherent imaging rather than only point ranging.

A different application domain is in-situ advanced manufacturing. Coaxial dual-comb LiDAR integrated into a laser micromachining station enabled 3D profiling with sub-micron axial precision without moving the workpiece [2504.09659]. Measured single-point standard deviation on rough, non-cooperative surfaces was $680\,\mathrm{nm}$ with no averaging at $\Delta f_r=20\,\mathrm{kHz}$ and $50\,\mu\mathrm{s}$ acquisition, improving to about $310\,\mathrm{nm}$ with $5$ averages and about $220\,\mathrm{nm}$ with $10$ averages [2504.09659]. The authors explicitly frame this as in-situ nondestructive testing and process evaluation during micromachining [2504.09659].

Atmospheric and remote-sensing uses appear in dual-comb DIAL. An electro-optic multi-heterodyne differential absorption lidar at $1572\,\mathrm{nm}$ measured atmospheric CO$_2$ over a $1.4\,\mathrm{km}$ optical path and simultaneously extracted radial wind speed from aerosol backscatter [2406.18208]. The path-average CO$_2$ retrieval had a precision of about $5\%$, while wind-speed measurements showed standard deviation typically below $0.3\,\mathrm{m/s}$ in most range gates, with pulse-limited range resolution $\Delta R\approx150\,\mathrm{m}$ and PRF-limited unambiguous range $\approx7.5\,\mathrm{km}$ [2406.18208]. This broadens the term “dual-comb LIDAR” beyond geometric ranging to multi-frequency absorption and Doppler sensing.

Two-photon dual-comb imaging extends the method to rough or discontinuous surfaces where coherent phase can be compromised by speckle. At a $40\,\mathrm{cm}$ stand-off, imaging of an aluminum test object produced point-cloud data with ranging accuracies of $9\,\mu\mathrm{m}$ to $38\,\mu\mathrm{m}$ and precisions averaging to $1.0\,\mu\mathrm{m}$ after $500\,\mathrm{ms}$ [2603.12729]. Continuous-streaming two-photon metrology with free-running $500\,\mathrm{MHz}$ Er,Yb:glass lasers further demonstrated capture of a four-minute audio track from the displacement of a loudspeaker-mounted mirror, with nearly $1\,\mu\mathrm{m}$ precision in $10\,\mathrm{ms}$ averaging [2603.07741].

## 6. Limitations, misconceptions, and current directions

A common misconception is that dual-comb LIDAR is uniformly free of ambiguity. In practice, ambiguity depends on the specific observable. In repetition-rate-offset timing architectures, smaller $\Delta f_{\rm rep}$ extends non-ambiguity range but reduces update rate [2509.01077], [2411.05585]. In repetition-rate-limited phase-slope systems, increasing $f_{\rm rep}$ improves precision but reduces $NAR=c/(2f_{\rm rep})$ [2202.05644]. FMCW and synthetic-wavelength systems distribute ambiguity differently, often into chirp duration or synthetic wavelength [2101.03952], [1707.05969]. Thus “absolute” ranging does not imply arbitrarily large ambiguity-free operation without architectural concessions.

Another misconception is that dual-comb systems inherently resolve multiple static targets inside one pixel. An explicit limitation study showed the impossibility to resolve different targets in a particular heterodyne phase-slope architecture when two static reflectors contribute to the same photodiode signal without Doppler separation [2202.05644]. The measured RF-beat phase becomes a nonlinear mixture, yielding either a false weighted distance or loss of linearity severe enough that no distance can be reported [2202.05644]. This is a fundamental caution for cluttered scenes and suggests the need for time gating, Doppler multiplexing, or alternative separation mechanisms.

Mechanical and thermal tuning of $\Delta f_{\rm rep}$ illustrate another active design trade-off. Mechanical delay lines can provide tuning rates around $500\,\mathrm{kHz/s}$ but suffer open-loop errors of hundreds of hertz and mechanical resonances [2509.01077]. Thermal bidirectional Lyot filtering reduces the differential-comb-line control uncertainty to $0.44\,\mathrm{Hz}$ without moving parts, but thermal tuning is naturally slower. This suggests that future systems may combine coarse fast tuning with fine thermal stabilization, although that specific hybrid strategy is not explicitly demonstrated in the cited work.

Environmental robustness remains a major issue for deployment. Outdoor long-range ranging is limited by atmospheric refractive-index fluctuations, motivating multi-point meteorology or dispersion-based correction [2411.05585]. In automotive or harsh environments, rain, fog, snow, dust, and water droplets on the window produce spurious echoes and artifacts; proposed mitigations include a synchronized spinning shield, moving-average and gated detection, and sensor fusion with radar and cameras [2508.03476]. In micromachining environments, optical isolation is needed to protect detectors during high-power machining pulses, while speckle on rough metallic surfaces can dominate the height uncertainty, with measured speckle errors around $5\,\mu\mathrm{m}$ on machined sections [2504.09659].

Current directions are correspondingly diverse. One route emphasizes ever faster, more integrated comb sources, including photonic integrated circuits, nanophotonic phased arrays, and ASIC/FPGA DSP for chip-scale solid-state LIDAR engines [1707.05969], [2101.03952]. A second route emphasizes robust free-running single-cavity sources with long operation times and low drift for industrial metrology [2411.05585], [2508.03476], [2509.01077]. A third route uses nonlinear or simplified detection, particularly two-photon cross-correlation, to eliminate high-rate digitization and relax $f_{\rm CEO}$ stabilization requirements [2108.10146], [2603.07741], [2603.12729]. A plausible implication is that the field is separating into application-specific regimes: ultrafast integrated ranging, fieldable coherent metrology, and low-data-burden precision sensing.

## 7. Representative performance landscape

The following examples summarize the range of operating regimes reported for dual-comb LIDAR and related dual-comb ranging systems.

| System | Key reported parameters | Representative outcome |
|---|---|---|
| Free-running single-cavity solid-state dual-comb | $\lambda_c\approx1055\,\mathrm{nm}$, $f_{\rm rep}=1.041\,\mathrm{GHz}$, $\Delta f_{\rm rep}=5.06\,\mathrm{kHz}$ | $0.1\,\mu\mathrm{m}$ single-shot ToF precision; $<20\,\mathrm{nm}$ phase precision; residuals below $3\,\mu\mathrm{m}$ over $40\,\mathrm{m}$ [2411.05585] |
| Thermally tuned bidirectional Lyot-filter fiber dual-comb | $k=4.4\,\mathrm{Hz}/^\circ\mathrm{C}$, control accuracy $\pm0.44\,\mathrm{Hz}$, $\Delta f_{\rm rep}$ from $\simeq210\,\mathrm{Hz}$ to $\simeq85\,\mathrm{Hz}$ | Non-ambiguous distance extended from $\simeq710\,\mathrm{km}$ to $\simeq1.8\times10^6\,\mathrm{m}$ [2509.01077] |
| Integrated DKS dual-comb LIDAR | $\Delta f\approx97.7\,\mathrm{MHz}$, $\approx115$ lines, $T_{\min}\approx10.3\,\mathrm{ns}$ | $97.7\,\mathrm{MHz}$ ranging rate; $12\,\mathrm{nm}$ Allan deviation at $14\,\mu\mathrm{s}$ [1707.05969] |
| Dual-soliton microcomb FMCW | $28$ to $\sim81$ channels, $T=10\,\mu\mathrm{s}$, $B\approx1.5$–$1.8\,\mathrm{GHz}$ | $2.8$ to $5.6\,\mathrm{MPix/s}$ line rates with parallel range and velocity [2101.03952] |
| In-situ micromachining dual-comb LiDAR | $1056\,\mathrm{nm}$, $18\,\mathrm{nm}$ bandwidth, $\Delta f_r=6.6\,\mathrm{kHz}$ | Sub-micron axial precision in coaxial 3D profiling; $\approx3\,\mathrm{min}$ for a $550\times300$ scan with five measurements per point [2504.09659] |
| Two-photon dual-comb LiDAR imaging | $f_{r1}=78.000000\,\mathrm{MHz}$, $f_{r2}=78.001000\,\mathrm{MHz}$, $\Delta f_r=1\,\mathrm{kHz}$ | $9$–$38\,\mu\mathrm{m}$ accuracy and $1.0\,\mu\mathrm{m}$ precision after $500\,\mathrm{ms}$ at $40\,\mathrm{cm}$ stand-off [2603.12729] |
| Continuous-streaming two-photon dual-comb | $f_{\rm rep}\approx540\,\mathrm{MHz}$, $\Delta f_{\rm rep}\approx10$–$20\,\mathrm{kHz}$ | Sustained $\sim11.5\,\mathrm{kHz}$ streaming, nearly $1\,\mu\mathrm{m}$ precision in $10\,\mathrm{ms}$ [2603.07741] |

Taken together, these results define dual-comb LIDAR as a family of ranging and remote-sensing techniques rather than a single instrument design. The common core is the controlled mapping of optical delay into a low-frequency observable using two combs with slightly different repetition rates. The main differentiators are the method used to preserve mutual coherence, the way ambiguity is managed, whether detection is coherent or nonlinear, and the application-specific balance among precision, update rate, data burden, and environmental robustness [2411.05585], [2509.01077], [1707.05969], [2108.10146], [2202.05644].

Source: https://www.emergentmind.com/topics/dual-comb-lidar