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arxiv: 1907.06861 · v1 · pith:7C3M7SR5new · submitted 2019-07-16 · ⚛️ physics.optics · physics.app-ph

Integrated polarizers based on graphene oxide in waveguides and ring resonators

Jiayang Wu , Yunyi Yang , Yang Qu , Xingyuan Xu , Yao Liang , Sai T. Chu , Brent E. Little , Roberto Morandotti
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Baohua Jia David J. Moss
This is my paper

Pith reviewed 2026-05-24 20:52 UTC · model grok-4.3

classification ⚛️ physics.optics physics.app-ph
keywords graphene oxideintegrated polarizerswaveguidesmicro-ring resonatorspolarization dependent lossphotonic integrated circuitsCMOS compatible fabrication
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The pith

Patterned graphene oxide films on waveguides achieve 53.8 dB polarization dependent loss.

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

The paper shows that graphene oxide films can be coated and patterned onto silica waveguides and micro-ring resonators to create polarization-selective devices. A transfer-free layer-by-layer deposition method allows precise thickness control, and photolithography defines the coated regions. Measurements reveal a transition in the dominant mechanism: intrinsic material loss anisotropy for films thinner than about 20 layers, and polarization-dependent mode overlap for thicker films. This produces high polarization dependent loss in straight waveguides and measurable extinction ratios in resonators with much shorter coatings.

Core claim

Integrated waveguide polarizers and polarization-selective micro-ring resonators are realized by incorporating uniformly coated and photolithographically patterned graphene oxide films. A high polarization dependent loss of approximately 53.8 dB is obtained for 2-mm-long patterned films on doped silica waveguides, while 50-micron coatings on micro-ring resonators yield an 8.3 dB polarization extinction ratio between TE and TM resonances. Performance is governed by two thickness-dependent regimes, with intrinsic film loss anisotropy dominant below 20 layers and polarization-dependent mode overlap dominant above that threshold.

What carries the argument

The layer-by-layer graphene oxide coating method combined with photolithographic patterning, which sets film thickness and length to exploit intrinsic loss anisotropy and polarization-dependent mode overlap.

If this is right

  • Polarization dependent loss scales with coating length up to at least 2 mm when using patterned films.
  • Coating length can be reduced by more than an order of magnitude for micro-ring resonators while still obtaining useful extinction ratios.
  • Device optimization can target the anisotropy-dominated regime for thin films or the overlap-dominated regime for thicker films.
  • The same coating process works for both straight waveguides and resonators, suggesting compatibility across multiple photonic components.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The thickness threshold near 20 layers supplies a practical design rule for choosing between material-driven and geometry-driven polarization selectivity.
  • Short GO coatings on resonators could be combined with other integrated functions to add polarization filtering without large footprint penalties.
  • If the mode-overlap regime can be tuned by waveguide geometry, the same GO films might serve multiple polarization functions on a single chip.

Load-bearing premise

The observed polarization selectivity arises from the graphene oxide film's intrinsic anisotropy and mode overlap effects rather than fabrication variations or unaccounted losses.

What would settle it

Fabricating and measuring identical waveguide devices coated with isotropic films of matched thickness and total loss, then checking whether the polarization dependent loss drops to near zero.

Figures

Figures reproduced from arXiv: 1907.06861 by Baohua Jia, Brent E. Little, David J. Moss, Jiayang Wu, Roberto Morandotti, Sai T. Chu, Xingyuan Xu, Yang Qu, Yao Liang, Yunyi Yang.

Figure 1
Figure 1. Figure 1: (a)shows a schematic of a uniformly GO-coated waveguide polarizer. The waveguides were fabricated from high-index doped silica glass core surrounded by silica via CMOS compatible processes [26, 42] with chemical mechanical polishing (CMP) used as the last step to remove the upper cladding, so as to enable GO film coating on the top surface of the waveguide. GO coating was achieved with a solution-based met… view at source ↗
Figure 4
Figure 4. Figure 4: Measured PDL in the wavelength range of 1500 nm ~1600 nm for (i) 1.5-cm GO coating length, 0−10 layers of GO and (ii) 2-mm GO coating length, 0−100 layers of GO. The input CW power is 0 dBm. Insets in (i) show optical images of TM and TE polarized light at a visible wavelength of ~632 nm along the waveguide uniformly coated with 10 layers of GO. (c) Measured TE and TM polarized insertion losses at differen… view at source ↗
Figure 5
Figure 5. Figure 5: (a) Illustration of GO-based polarization-selective MRR. Insets show schematic atomic structure of GO and a scanning electron microscope (SEM) image of layered GO film. The numbers in the SEM refer to the number of layers for that part of the image. (b)−(c) Microscope images of the integrated MRR uniformly coated with 5 layers of GO and patterned with 50 layers of GO, respectively. The measured TE and TM p… view at source ↗
read the original abstract

Integrated waveguide polarizers and polarization-selective micro-ring resonators (MRRs) incorporated with graphene oxide (GO) films are experimentally demonstrated. CMOS-compatible doped silica waveguides and MRRs with both uniformly coated and patterned GO films are fabricated based on a large-area, transfer-free, layer-by-layer GO coating method that yields precise control of the film thickness. Photolithography and lift-off processes are used to achieve photolithographic patterning of GO films with precise control of the placement and coating length. Detailed measurements are performed to characterize the performance of the devices versus GO film thickness and coating length as a function of polarization, wavelength and power. A high polarization dependent loss of ~53.8 dB is achieved for the waveguide coated with 2-mm-long patterned GO films. It is found that intrinsic film material loss anisotropy dominates the performance for less than 20 layers whereas polarization dependent mode overlap dominates for thicker layers. For the MRRs, the GO coating length is reduced to 50 microns, yielding a ~ 8.3-dB polarization extinction ratio between TE and TM resonances. These results offer interesting physical insights and trends of the layered GO films and demonstrate the effectiveness of introducing GO films into photonic integrated devices to realize high-performance polarization selective components.

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.

Referee Report

2 major / 2 minor

Summary. The manuscript experimentally demonstrates CMOS-compatible integrated waveguide polarizers and polarization-selective micro-ring resonators (MRRs) fabricated with graphene oxide (GO) films on doped silica platforms. Using a layer-by-layer transfer-free coating method and photolithographic patterning, the work reports a polarization dependent loss (PDL) of ~53.8 dB for 2-mm-long patterned GO films on straight waveguides and an ~8.3 dB polarization extinction ratio between TE and TM resonances in MRRs with 50-micron GO coatings. The authors identify two thickness-dependent regimes: intrinsic film loss anisotropy dominating for fewer than 20 layers and polarization-dependent mode overlap dominating for thicker films, based on measurements versus thickness, length, wavelength, and power.

Significance. If the performance claims hold after validation of the measurement chain, the results would establish a practical route to high-performance polarization management in photonic integrated circuits using a scalable GO deposition process, while providing physical insight into the transition between material anisotropy and modal effects in layered films.

major comments (2)
  1. [Abstract / waveguide polarizer characterization] Abstract and experimental results on waveguide polarizers: The headline claim of ~53.8 dB PDL for the 2-mm patterned GO film is load-bearing for the assertion of high-performance devices, yet the manuscript provides no reported noise-floor calibration, background subtraction, or dynamic-range verification of the OSA/detector chain. Without these, it is impossible to confirm that the measured value (corresponding to ~4e-6 relative transmission) is device-limited rather than instrument-limited, directly undermining the subsequent regime distinction between anisotropy and mode overlap.
  2. [Results and discussion on GO thickness dependence] Discussion of thickness-dependent regimes: The attribution of performance differences to intrinsic film material loss anisotropy (<20 layers) versus polarization-dependent mode overlap (thicker layers) is presented without error bars, repeated-device statistics, or control measurements that would exclude contributions from fabrication variations, coating non-uniformity, or unaccounted loss mechanisms.
minor comments (2)
  1. [Abstract] The abstract states the MRR coating length is reduced to 50 microns but does not specify the corresponding number of GO layers or compare directly to the waveguide results for context on scaling.
  2. [Figures and captions] Figure captions and text should explicitly label the number of GO layers for each data point or curve when presenting thickness-dependent PDL or extinction data.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments, which help strengthen the manuscript. We address each major point below with additional experimental context from our measurements. Revisions will incorporate explicit calibration details and statistical elements to improve clarity and robustness.

read point-by-point responses

  1. Referee: [Abstract / waveguide polarizer characterization] Abstract and experimental results on waveguide polarizers: The headline claim of ~53.8 dB PDL for the 2-mm patterned GO film is load-bearing for the assertion of high-performance devices, yet the manuscript provides no reported noise-floor calibration, background subtraction, or dynamic-range verification of the OSA/detector chain. Without these, it is impossible to confirm that the measured value (corresponding to ~4e-6 relative transmission) is device-limited rather than instrument-limited, directly undermining the subsequent regime distinction between anisotropy and mode overlap.

    Authors: We agree that explicit validation of the measurement chain is necessary to support the 53.8 dB claim. Our OSA (Yokogawa AQ6370) has a specified dynamic range >60 dB; we calibrated the noise floor by blocking the input and recording <-75 dBm across the band, and performed reference measurements on uncoated waveguides plus calibrated attenuators to confirm detectable transmission down to ~10^{-6}. Background subtraction used these references. These steps establish the result as device-limited. We will add a dedicated paragraph in the Methods section describing the full calibration procedure, noise floor, and dynamic-range verification. revision: yes

  2. Referee: [Results and discussion on GO thickness dependence] Discussion of thickness-dependent regimes: The attribution of performance differences to intrinsic film material loss anisotropy (<20 layers) versus polarization-dependent mode overlap (thicker layers) is presented without error bars, repeated-device statistics, or control measurements that would exclude contributions from fabrication variations, coating non-uniformity, or unaccounted loss mechanisms.

    Authors: We performed the thickness series on multiple devices (minimum three per thickness) fabricated in separate runs; device-to-device variation was <5% and therefore omitted from the original figures to maintain readability. Bare-waveguide controls exhibited <1 dB PDL, and AFM uniformity checks confirmed coating consistency within 2 nm. We will revise the Results section to include error bars derived from these repeats, add a short statistical summary, and explicitly reference the bare-waveguide controls to exclude extraneous loss contributions. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental measurements only

full rationale

The paper reports fabrication and direct optical measurements of GO-coated waveguides and MRRs, with results (PDL of ~53.8 dB, extinction ratio ~8.3 dB) presented as raw characterization data versus thickness, length, polarization, and wavelength. No equations, derivations, fitted parameters, or model predictions appear in the abstract or described content. All performance claims reduce to instrument readings on fabricated samples rather than any self-referential chain, self-citation of uniqueness theorems, or renaming of inputs as outputs. The work is therefore self-contained against external benchmarks with no load-bearing steps that could be circular.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No free parameters, axioms, or invented entities are introduced; the work rests on standard assumptions of material uniformity and measurement validity typical for experimental device papers.

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