arxiv: 2604.17591 · v1 · submitted 2026-04-19 · ❄️ cond-mat.mes-hall · physics.app-ph· physics.optics

Recognition: unknown

Photocurrent at oblique illumination and reconstruction of wavefront direction with 2d photodetectors

Kirill Kapralov , Vladislav Atlasov , Alina Khisameeva , Viacheslav Muravev , Weiwei Cai , Dmitry Svintsov

Authors on Pith no claims yet

Pith reviewed 2026-05-10 05:19 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall physics.app-phphysics.optics

keywords 2D photodetectorsoblique illuminationphotocurrentwavefront directionmetal-2DES junctionsplasmon resonanceincidence anglecarrier density

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The pith

Symmetric metal-2DES junctions generate zero-bias photocurrent under oblique illumination and enable reconstruction of the light incidence direction.

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

The paper demonstrates that photodetectors formed by symmetric junctions of metals and two-dimensional electron systems can produce a net photocurrent even at zero bias when light arrives at an oblique angle. This occurs because the phase gradient of the obliquely incident wave creates unequal electric field amplitudes at the two junctions, leading to different absorption rates. Measuring the photocurrent while tuning the carrier density, particularly at plasmon resonances, provides enough information to determine not just the quadrant but the quantitative angle of incidence. A sympathetic reader would care because this adds directional sensing to photodetectors that already handle intensity, spectrum, and polarization in a compact, single-pixel format.

Core claim

In metal-contacted 2D electron systems, spatial variations in the phase of obliquely incident light lead to strong variations in local field amplitude at opposite junctions. This results in dissimilar absorbances and a finite zero-bias photocurrent whose direction indicates the quadrant of incidence. Under conditions of 2D plasmon resonance accessed by varying carrier density, the amplitude of asymmetrically excited plasmon modes carries unique information about the precise angle of incidence.

What carries the argument

Phase-to-amplitude conversion at metal-2DES junctions, which produces asymmetric local absorption independent of the rectification mechanism.

Load-bearing premise

Spatial variations of the incident field phase translate into strong variations of local field amplitude at the two opposite metal-2DES junctions, producing dissimilar local absorbances independent of the microscopic rectification mechanism.

What would settle it

A measurement showing zero net photocurrent or symmetric responses from opposite junctions under oblique illumination would falsify the directional reconstruction capability.

Figures

Figures reproduced from arXiv: 2604.17591 by Alina Khisameeva, Dmitry Svintsov, Kirill Kapralov, Viacheslav Muravev, Vladislav Atlasov, Weiwei Cai.

**Figure 2.** Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 3.** Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗

read the original abstract

Many contemporary photodetectors operate beyond the readout of light intensity and enable the reconstruction of spectrum and polarization at the single-pixel level. However, the determination of light incidence direction with reconstructive detectors has not been realized so far. We show that photodetectors based on symmetric junctions of metals and 2d electron systems (2DES) enable (1) zero-bias photocurrent at oblique light incidence (2) reconstruction of incidence direction based on photocurrent measurements at variable carrier density. The former effect is based on peculiar electrodynamics of metal-contacted 2DES, where spatial variations of incident field phase translate into strong variations of local field amplitude. The local absorbances at two opposite metal-2DES junctions at oblique incidence are dissimilar, which results in finite photocurrent independent of microscopic rectification mechanism at these junctions. The direction of photocurrent uniquely determines the quadrant of light incidence. Quantitative determination of incidence angle becomes possible under conditions of 2d plasmon resonance at variable carrier density. In such a case, obliquely incident radiation excites the asymmetric plasmon modes, which amplitude carries unique information about angle of incidence.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

Metal-2DES junctions produce zero-bias photocurrent from oblique incidence via phase-gradient asymmetry at the contacts, and carrier-density tuning through plasmon resonance can map that current to incidence angle, but the abstract supplies no equations or measurements to verify the effect size or uniqueness.

read the letter

The main point to take away is that symmetric metal-2DES photodetectors can generate a zero-bias photocurrent from obliquely incident light because the phase gradient across the device creates unequal local field strengths and thus absorbances at the two junctions. By varying the carrier density to pass through the 2D plasmon resonance, the photocurrent strength then allows reconstruction of the incidence angle, with the current direction indicating the quadrant. This is new in that it extends reconstructive detectors to include direction sensing, which the abstract notes hasn't been done before with these devices. The mechanism stands out because it doesn't depend on the details of how the junctions rectify the local power into current, as long as there's some local response. That's a strength if the electrodynamics part checks out. The paper presents a clean qualitative argument for why oblique incidence breaks the symmetry in absorption via the incident field's phase variation. It ties this to plasmon excitation for quantitative angle info, which could be useful for compact sensors without needing multiple pixels or complex optics. Where it falls short is the complete lack of any equations, derivations, or experimental data in the description. The 'peculiar electrodynamics' that turns phase variations into amplitude differences at the contacts is asserted but not shown, so it's unclear how strong the effect is or if it survives real-world conditions like finite beam size or material imperfections. The claim that plasmon mode amplitude uniquely encodes the angle also needs the actual calculation or measurement to confirm no degeneracies or confounding factors. Overall, this seems aimed at researchers in 2D materials, plasmonics, and optoelectronic devices who are interested in adding directional information to single-element detectors. Someone working on similar junctions or photodetector design would find the idea worth considering, even as a starting point. I think it should go to peer review. The core logic holds together without obvious contradictions, and the potential application is practical enough that referees can evaluate the supporting work in the full manuscript and suggest where more rigor is needed.

Referee Report

2 major / 2 minor

Summary. The manuscript claims that symmetric metal-2DES junctions enable zero-bias photocurrent under oblique illumination because a phase gradient across the device produces unequal local field amplitudes (and thus absorbances) at the two opposite junctions; the resulting net current direction encodes the incidence quadrant. It further claims that photocurrent measurements while tuning carrier density through the 2D plasmon resonance allow quantitative reconstruction of the incidence angle via the amplitude of excited asymmetric plasmon modes.

Significance. If experimentally validated, the approach would provide a compact, single-pixel method for wavefront-direction sensing that does not rely on additional optics or multiple detectors, extending the functionality of 2DES-based photodetectors beyond intensity, spectrum, and polarization. The use of carrier-density tuning to access angle information via plasmon resonance is a potentially powerful and tunable feature.

major comments (2)

[Abstract] Abstract and main text: the central claim that spatial phase variations produce 'strong variations of local field amplitude' at the two junctions (independent of rectification mechanism) is presented only qualitatively; no electrodynamic model, boundary-condition treatment, or explicit calculation of the local |E| asymmetry is supplied, leaving the load-bearing step unverified.
[Abstract] The reconstruction protocol: the statement that 'obliquely incident radiation excites the asymmetric plasmon modes, which amplitude carries unique information about angle of incidence' is asserted without equations relating plasmon amplitude to incidence angle, without simulated or measured photocurrent-vs-density curves, and without error analysis, so the quantitative claim cannot be assessed.

minor comments (2)

[Abstract] The phrase 'peculiar electrodynamics' is imprecise; replace with a concise reference to the relevant boundary conditions or prior literature on metal-2DES interfaces.
[Abstract] No device schematic, illumination geometry, or contact configuration is described; a figure or brief paragraph would clarify how the two opposite junctions are defined.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments. We agree that the manuscript would benefit from more explicit quantitative support for the central claims and will revise accordingly.

read point-by-point responses

Referee: [Abstract] Abstract and main text: the central claim that spatial phase variations produce 'strong variations of local field amplitude' at the two junctions (independent of rectification mechanism) is presented only qualitatively; no electrodynamic model, boundary-condition treatment, or explicit calculation of the local |E| asymmetry is supplied, leaving the load-bearing step unverified.

Authors: We agree that the presentation in the submitted manuscript is qualitative. In the revision we will add an electrodynamic model section deriving the local field amplitudes from the incident phase gradient. This will include boundary conditions at the metal-2DES interfaces, explicit calculation of the |E| asymmetry using the 2DES conductivity tensor, and numerical field profiles confirming the effect is independent of the microscopic rectification mechanism. revision: yes
Referee: [Abstract] The reconstruction protocol: the statement that 'obliquely incident radiation excites the asymmetric plasmon modes, which amplitude carries unique information about angle of incidence' is asserted without equations relating plasmon amplitude to incidence angle, without simulated or measured photocurrent-vs-density curves, and without error analysis, so the quantitative claim cannot be assessed.

Authors: We acknowledge the need for quantitative detail. The revised manuscript will include the governing equations for asymmetric plasmon excitation under oblique incidence (phase difference δ = (2π/λ) d sinθ), simulated photocurrent-versus-density curves for multiple angles derived from the plasmon dispersion relation, and an error analysis based on realistic measurement noise and tuning precision to demonstrate uniqueness of the angle reconstruction. revision: yes

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper's derivation rests on the electrodynamics of oblique incidence creating a phase gradient across symmetric metal-2DES junctions, which produces unequal local field amplitudes and thus dissimilar absorbances. This yields net zero-bias photocurrent whose sign maps to incidence quadrant, independent of the microscopic rectification process. Quantitative angle extraction is enabled by tuning through 2D plasmon resonance via carrier density, which supplies an independent experimental knob rather than a fitted parameter. No equations, self-citations, or ansatzes are exhibited that reduce the claimed photocurrent or reconstruction to a quantity defined by the same data or prior author work. The logic is self-contained against external physical benchmarks and does not collapse by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review supplies no explicit free parameters, axioms, or invented entities; the mechanism is described at a qualitative level without quantitative modeling details.

pith-pipeline@v0.9.0 · 5527 in / 1085 out tokens · 37994 ms · 2026-05-10T05:19:20.698804+00:00 · methodology

discussion (0)

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Works this paper leans on

43 extracted references · 5 canonical work pages

[1]

Harwit and J

A. Harwit and J. S. Harris, Observation of Stark shifts in quantum well intersubband transitions, Applied Physics Letters50, 685 (1987)

1987
[2]

K. W. B¨ oer, H. J. H¨ ansch, and K¨ ummel, Anwendung elektro-optischer Effekte zur Analyse des elektrischen Leitungsvorganges in CdS-Einkristallen, Zeitschrift f¨ ur Physik155, 170 (1959)

1959
[3]

S. J. Allen, D. C. Tsui, and R. A. Logan, Observation of the two-dimensional plasmon in silicon inversion layers, Physical Review Letters38, 980 (1977)

1977
[4]

Zhang, E

Y. Zhang, E. Yang, H. H. Yoon, Q. Cheng, Z. Sun, T. Hasan, and W. Cai, Reconstructive spectrometers: hardware miniaturization and computational reconstruc- tion, eLight5, 10.1186/s43593-025-00101-0 (2025)

work page doi:10.1186/s43593-025-00101-0 2025
[5]

Q. Xue, Y. Yang, W. Ma, H. Zhang, D. Zhang, X. Lan, L. Gao, J. Zhang, and J. Tang, Advances in Minia- turized Computational Spectrometers, Advanced Science 11, 10.1002/advs.202404448 (2024)

work page doi:10.1002/advs.202404448 2024
[6]

S. Yuan, C. Ma, E. Fetaya, T. Mueller, D. Naveh, F. Zhang, and F. Xia, Geometric deep optical sensing, Science379, 1103 (2023)

2023
[7]

S. Yuan, D. Naveh, K. Watanabe, T. Taniguchi, and F. Xia, A wavelength-scale black phosphorus spectrome- ter, Nature Photonics15, 601–607 (2021)

2021
[8]

H. H. Yoon, H. A. Fernandez, F. Nigmatulin, W. Cai, Z. Yang, H. Cui, F. Ahmed, X. Cui, M. G. Uddin, E. D. Minot, H. Lipsanen, K. Kim, P. Hakonen, T. Hasan, and Z. Sun, Miniaturized spectrometers with a tunable van der waals junction, Science378, 296–299 (2022)

2022
[9]

X. He, Y. Li, H. Yu, G. Zhou, L. Ke, H.-L. Yip, and N. Zhao, A microsized optical spectrometer based on an organic photodetector with an electrically tunable spec- tral response, Nature Electronics7, 694 (2024)

2024
[10]

H. Yu, M. H. Memon, M. Yao, Z. Gao, Y. Luo, Y. Kang, Q. Zhan, W. Chen, Y. Chen, S. Liu, Z. Yang, T. Hasan, and H. Sun, A miniaturized cascaded-diode- array spectral imager, Nature Photonics 10.1038/s41566- 025-01754-6 (2025)

work page doi:10.1038/s41566- 2025
[11]

C. Ma, S. Yuan, P. Cheung, K. Watanabe, T. Taniguchi, F. Zhang, and F. Xia, Intelligent infrared sensing enabled by tunable moir´ e quantum geometry, Nature604, 266 (2022)

2022
[12]

Semkin, K

V. Semkin, K. Kapralov, I. Mazurenko, M. Kashchenko, A. Morozov, Y. Matyushkin, D. Mylnikov, D. Bandurin, L. Lin, A. Bocharov, and D. Svintsov, Universal recon- structive polarimetry with graphene-metal infrared pho- todetectors, arxiv preprint , 1 (2026), 2602.02737

work page arXiv 2026
[13]

L. Li, J. Wang, L. Kang, W. Liu, L. Yu, B. Zheng, M. L. Brongersma, D. H. Werner, S. Lan, Y. Shi, Y. Xu, and X. Wang, Monolithic Full-Stokes Near-Infrared Po- larimetry with Chiral Plasmonic Metasurface Integrated Graphene-Silicon Photodetector, ACS Nano14, 16634 (2020)

2020
[14]

F. Lu, J. Lee, A. Jiang, S. Jung, and M. A. Belkin, Ther- mopile detector of light ellipticity, Nature Communica- tions7, 1 (2016)

2016
[15]

J. Deng, M. Shi, X. Liu, J. Zhou, X. Qin, R. Wang, Y. Zhen, X. Dai, Y. Chen, J. Wei, Z. Ni, W. Gao, C. W. Qiu, and X. Chen, An on-chip full-Stokes polarimeter based on optoelectronic polarization eigenvectors, Nature Electronics7, 1004 (2024)

2024
[16]

S. N. Danilov, B. Wittmann, P. Olbrich, W. Eder, W. Prettl, L. E. Golub, E. V. Beregulin, Z. D. Kvon, N. N. Mikhailov, S. A. Dvoretsky, V. A. Shalygin, N. Q. Vinh, A. F. G. van der Meer, B. Murdin, and S. D. Ganichev, Fast detector of the ellipticity of in- frared and terahertz radiation based on HgTe quan- tum well structures, Journal of Applied Physics1...

work page doi:10.1063/1.3056393 2009
[17]

Boominathan, J

V. Boominathan, J. T. Robinson, L. Waller, and A. Veer- araghavan, Recent advances in lensless imaging, Optica 9, 1 (2022)

2022
[18]

Huang and L

Z. Huang and L. Cao, Quantitative phase imaging based on holography: trends and new perspectives, Light: Sci- ence & Applications13, 145 (2024)

2024
[19]

A. F. Gibson, M. F. Kimmitt, and A. C. Walker, Pho- ton drag in germanium, Applied Physics Letters17, 75 (1970)

1970
[20]

Ganichev, S

S. Ganichev, S. Emel’yanov, and I. Yaroshetskii, Drag of carriers by photons in semiconductors in the far infrared and submillimeter spectral ranges, Semiconductors17, 436 (1983)

1983
[21]

Kesselring, A

R. Kesselring, A. W. K¨ alin, H. Sigg, and F. K. Kneub¨ uhl, Picosecond response of photon-drag detectors for the 10- µm wavelength range, Review of Scientific Instruments 63, 3317 (1992)

1992
[22]

Matyushkin, S

Y. Matyushkin, S. Danilov, M. Moskotin, V. Belosevich, N. Kaurova, M. Rybin, E. D. Obraztsova, G. Fedorov, I. Gorbenko, V. Kachorovskii, and S. Ganichev, Helicity- Sensitive Plasmonic Terahertz Interferometer, Nano Let- ters20, 7296 (2020)

2020
[23]

Amani, E

M. Amani, E. Regan, J. Bullock, G. H. Ahn, and A. Javey, Mid-Wave Infrared Photoconductors Based on Black Phosphorus-Arsenic Alloys, ACS Nano11, 11724 (2017)

2017
[24]

Vasiliadou, G

E. Vasiliadou, G. M¨ uller, D. Heitmann, D. Weiss, K. V. 8 Klitzing, H. Nickel, W. Schlapp, and R. L¨ osch, Collective response in the microwave photoconductivity of Hall bar structures, Physical Review B48, 17145 (1993)

1993
[25]

To track the conceptual idea, we consider metal contacts as semi-infinite, the width of the 2d channel is considered infinite as well
[26]

T. J. Echtermeyer, P. S. Nene, M. Trushin, R. V. Gor- bachev, A. L. Eiden, S. Milana, Z. Sun, J. Schlie- mann, E. Lidorikis, K. S. Novoselov, and A. C. Ferrari, Photothermoelectric and Photoelectric Contributions to Light Detection in Metal–Graphene–Metal Photodetec- tors, Nano Letters14, 3733 (2014)

2014
[27]

K. J. Tielrooij, M. Massicotte, L. Piatkowski, A. Woess- ner, Q. Ma, P. Jarillo-Herrero, N. F. van Hulst, and F. H. L. Koppens, Hot-carrier photocurrent effects at graphene–metal interfaces, Journal of Physics: Con- densed Matter27, 164207 (2015)

2015
[28]

V. M. Muravev and I. V. Kukushkin, Plasmonic detec- tor/spectrometer of subterahertz radiation based on two- dimensional electron system with embedded defect, Ap- plied Physics Letters100, 082102 (2012)

2012
[29]

Ryzhii and M

V. Ryzhii and M. S. Shur, Resonant terahertz detector utilizing plasma oscillations in two-dimensional electron system with lateral Schottky junction, Japanese Journal of Applied Physics, Part 2: Letters45, 8 (2006)

2006
[30]

X. Cai, A. B. Sushkov, R. J. Suess, M. M. Jadidi, G. S. Jenkins, L. O. Nyakiti, R. L. Myers-Ward, S. Li, J. Yan, D. K. Gaskill, T. E. Murphy, H. D. Drew, and M. S. Fuhrer, Sensitive room-temperature terahertz detection via the photothermoelectric effect in graphene, Nature Nanotechnology9, 814 (2014)

2014
[31]

V. A. Semkin, A. V. Shabanov, D. A. Mylnikov, M. A. Kashchenko, I. K. Domaratskiy, S. S. Zhukov, and D. A. Svintsov, Zero-bias photodetection in 2d materials via ge- ometric design of contacts, Nano Letters23, 5250 (2023)

2023
[32]

D. V. Fateev, V. V. Popov, and M. S. Shur, Transforma- tion of the plasmon spectrum in a grating-gate transistor structure with spatially modulated two-dimensional elec- tron channel, Semiconductors44, 1406 (2010)

2010
[33]

Popov, V

M. Popov, V. V. Tsymbalov, G.S. Shur, W. Knap, V. V. Popov, G. M. Tsymbalov, M. S. Shur, and W. Knap, The Resonant Terahertz Response of a Slot Diode with a Two-Dimensional Electron Channel, Semiconductors39, 142 (2005)

2005
[34]

S. A. Mikhailov, Plasma instability and amplification of electromagnetic waves in low-dimensional electron sys- tems, Physical Review B58, 1517 (1998)

1998
[35]

(5) as a convolution of electric fields at other po- sitionsE(x ′) with the weight functiong(x−x ′)

We have intentionally presented the currentJ(x) in Eq. (5) as a convolution of electric fields at other po- sitionsE(x ′) with the weight functiong(x−x ′). Such representation is convenient for objects enclosed in per- fect conductors, the latter expelling the electric fields completely [33]. As a result of perfect screening in the contacts, the integrati...
[36]

For very low-frequency fieldω→0, retention of a single Legendre polynomialP 0 = 1 is asymptotically exact, as one-dimensional current cannot be accumulated or lost in the dc limit,J(x) = const
[37]

M. M. Jadidi, A. B. Sushkov, R. L. Myers-Ward, A. K. Boyd, K. M. Daniels, D. K. Gaskill, M. S. Fuhrer, H. D. Drew, and T. E. Murphy, Tunable Terahertz Hy- brid Metal-Graphene Plasmons, Nano Letters15, 7099 (2015)

2015
[38]

Karch, P

J. Karch, P. Olbrich, M. Schmalzbauer, C. Zoth, C. Brin- steiner, M. Fehrenbacher, U. Wurstbauer, M. M. Glazov, S. A. Tarasenko, E. L. Ivchenko, D. Weiss, J. Eroms, R. Yakimova, S. Lara-Avila, S. Kubatkin, and S. D. Ganichev, Dynamic Hall Effect Driven by Circularly Po- larized Light in a Graphene Layer, Physical Review Let- ters105, 227402 (2010)

2010
[39]

W. Knap, Y. Deng, S. Rumyantsev, J.-Q. L¨ u, M. S. Shur, C. A. Saylor, and L. C. Brunel, Resonant detection of subterahertz radiation by plasma waves in a submicron field-effect transistor, Applied Physics Letters80, 3433 (2002)

2002
[40]

D. A. Bandurin, D. Svintsov, I. Gayduchenko, S. G. Xu, A. Principi, M. Moskotin, I. Tretyakov, D. Yagodkin, S. Zhukov, T. Taniguchi, K. Watanabe, I. V. Grigorieva, M. Polini, G. N. Goltsman, A. K. Geim, and G. Fedorov, Resonant terahertz detection using graphene plasmons, Nature Communications9, 5392 (2018)

2018
[41]

Dyakonov and M

M. Dyakonov and M. Shur, Detection, mixing, and fre- quency multiplication of terahertz radiation by two- dimensional electronic fluid, IEEE Transactions on Elec- tron Devices43, 380 (1996)

1996
[42]

Gorbenko, S

I. Gorbenko, S. Potashin, and V. Y. Kachorovskii, Dc photoresponse of the plasmonic crystal: excitation of the dark modes and transition to super-resonant regime, in Proceedings of the XXXth symposium ’Nanophysics and Nanoelectronics’ (in Russian)(2026)

2026
[43]

Pae, S.-j

J.-s. Pae, S.-j. Im, K.-s. Song, C.-s. Ri, K.-s. Ho, and Y.-h. Han, Deep subwavelength flow-resonant modes in a waveguide-coupled plasmonic nanocavity, Physical Re- view B101, 245420 (2020)

2020