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arxiv: 2605.12348 · v2 · submitted 2026-05-12 · ⚛️ physics.optics

Transmission of signals in the 300 GHz band with a bit-error rate below {10}⁻⁹ using a soliton comb

Mantaro Imamura , Ryo Sugano , Ayaka Yomoda , Atsuro Shirasaki , Koya Tanikawa , Soma Kogure , Shun Fujii , Takasumi Tanabe This is my paper

Pith reviewed 2026-05-14 20:48 UTC · model grok-4.3

classification ⚛️ physics.optics
keywords soliton microcombterahertz communication300 GHz bandsilicon nitride resonatoron-off keyingbit error ratephotonic THz linkintensity modulation
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The pith

A soliton microcomb in a silicon nitride microring enables error-free 10 Gbps transmission at 300 GHz with simple on-off keying.

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

The paper shows that a soliton microcomb generated inside an integrated silicon nitride resonator can produce a stable carrier wave at 300 GHz. This carrier supports intensity-modulation direct-detection transmission at 10 Gbps while keeping the bit-error rate below 10 to the minus 9 without forward error correction or complex signal processing. The demonstration was performed in a short back-to-back waveguide setup, yet the measured power threshold is presented as evidence that free-space links of several tens of meters become practical once high-gain antennas and THz amplifiers are added. The work therefore positions soliton microcombs as a low-complexity photonic source for short-range fiber-wireless systems. A sympathetic reader would see this as a step toward replacing more elaborate coherent THz transmitters with simpler intensity-based links.

Core claim

The central claim is that a soliton microcomb generated in an integrated silicon nitride microring resonator produces a 300 GHz wave that supports error-free 10 Gbps on-off keying transmission with bit-error rate below 10 to the minus 9 in a simple intensity-modulation direct-detection architecture, without forward error correction or offline processing, and with power levels that indicate feasibility for free-space distances of several tens of meters using high-gain antennas and THz amplifiers.

What carries the argument

The soliton microcomb generated inside a silicon nitride microring resonator, which supplies a stable, low-noise multi-frequency spectrum from which a single line is extracted and modulated to create the 300 GHz carrier.

If this is right

  • Stable transmission at 10 Gbps with bit-error rate below 10 to the minus 9 is possible using only intensity modulation and direct detection.
  • No forward error correction or advanced signal processing is required to reach the error-free threshold.
  • The measured power levels support extension to free-space links of several tens of meters when high-gain antennas and THz amplifiers are employed.
  • The architecture is suitable for short-range fiber-wireless integrated systems.

Where Pith is reading between the lines

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

  • The approach could simplify THz transmitter hardware by avoiding coherent modulation and detection components.
  • Integration of the silicon nitride resonator with existing photonic platforms may enable compact, low-cost THz sources for wireless extension of fiber networks.
  • Real-world tests in outdoor or indoor environments would be needed to confirm that additional impairments such as atmospheric absorption or multipath do not raise the error rate above the demonstrated threshold.

Load-bearing premise

The error-free power threshold measured in the short back-to-back waveguide setup will continue to support acceptable performance once real free-space propagation losses, antenna gains, and amplifier noise are introduced.

What would settle it

A direct measurement of bit-error rate after the 300 GHz signal has propagated through free space for 20 to 50 meters using the same soliton comb source together with high-gain antennas and THz amplifiers.

Figures

Figures reproduced from arXiv: 2605.12348 by Atsuro Shirasaki, Ayaka Yomoda, Koya Tanikawa, Mantaro Imamura, Ryo Sugano, Shun Fujii, Soma Kogure, Takasumi Tanabe.

Figure 1
Figure 1. Figure 1: THz band wireless communication by photomixing. [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Experimental setup for soliton comb generation. Pump LD: Pump laser diode, EOM: Electro-optic modulator, [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 7
Figure 7. Figure 7: shows the photocurrent and UTC-PD output power as functions of the input optical power. Both the photocur￾rent and the generated THz power increased monotonically with increasing optical input power, and the UTC-PD output power exhibited an approximately linear dependence. At the maximum photocurrent of 7.0 mA, the UTC-PD output power reached −10.15 dBm [PITH_FULL_IMAGE:figures/full_fig_p003_7.png] view at source ↗
Figure 4
Figure 4. Figure 4: Transfer function measured by the VNA [PITH_FULL_IMAGE:figures/full_fig_p003_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Experimental setup for transmission in the 300 GHz. OC: Optical coupler, BPF: Band-pass filter, PC: Polarization con [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: UTC-PD input. 13.5 14 14.5 15 15.5 UTC-PD Input Power (dBm) -15 -14 -13 -12 -11 -10 UTC-PD Output Power (dBm) 4 4.5 5 5.5 6 6.5 7 7.5 Photocurrent (mA) THz Power Photocurrent [PITH_FULL_IMAGE:figures/full_fig_p004_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: UTC-PD output power and photocurrent. tens of meters when combined with high-gain antennas and THz amplification. It should be noted, however, that the Friis equation assumes ideal free-space propagation. In practical scenarios, additional impairments such as multipath propagation, beam misalign￾ment, absorption, and scattering may introduce substantial losses and degrade link performance. Moreover, near-f… view at source ↗
read the original abstract

To address the increasing demand for ultra-high-capacity wireless communication, terahertz (THz) frequencies near 300 GHz are attracting attention as a new spectral frontier. This work presents the first experimental demonstration of error-free (BER $< 1\times10^{-9}$) 10 Gbps transmission in the 300 GHz band using a soliton microcomb generated in an integrated silicon nitride (SiN) microring resonator. While many previous microcomb-based THz demonstrations have focused on coherent modulation formats and operation near the forward-error-correction (FEC) limit, this work investigates a simple intensity-modulation/direct-detection (IM-DD) on-off keying (OOK) architecture suitable for low-complexity THz links and fiber-wireless integrated systems. Although the experiment was conducted in a short back-to-back waveguide configuration, the generated THz wave enabled stable low-BER transmission without FEC or advanced offline signal processing. Analysis of the error-free threshold power indicates the feasibility of free-space transmission over several tens of meters with high-gain antennas and THz-band amplifiers. These results demonstrate the feasibility of robust low-complexity THz photonic links based on soliton microcombs for short-range fiber-wireless integrated systems.

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

1 major / 1 minor

Summary. The manuscript reports the first experimental demonstration of error-free (BER < 10^{-9}) 10 Gbps transmission in the 300 GHz band using a soliton microcomb generated in an integrated SiN microring resonator. The experiment employs a simple IM-DD OOK architecture in a short back-to-back waveguide configuration, achieving stable low-BER performance without FEC or advanced signal processing. Analysis of the measured error-free threshold power is used to project feasibility for free-space transmission over several tens of meters with high-gain antennas and THz-band amplifiers.

Significance. The back-to-back experimental results provide credible evidence for low-complexity THz links based on integrated soliton combs, which could be valuable for fiber-wireless integrated systems if the free-space projection holds. The work strengthens the case for photonic THz sources in short-range applications by demonstrating robust performance at high data rates with minimal receiver complexity.

major comments (1)
  1. [Free-space feasibility analysis (abstract and conclusion)] The feasibility claim for free-space transmission over several tens of meters (stated in the abstract and repeated in the conclusion) rests on analysis of the error-free threshold power but omits a quantitative link budget. No explicit accounting is provided for 300 GHz atmospheric absorption (typically 10-20 dB/km), beam divergence losses, or specific high-gain antenna performance, which directly affects whether the measured threshold supports the stated range.
minor comments (1)
  1. [Abstract and experimental methods] The abstract and methods section should explicitly state the physical length of the back-to-back waveguide configuration and the exact BER values achieved at the reported power levels for improved reproducibility.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive review and the recommendation for major revision. We have addressed the single major comment by adding the requested quantitative analysis to the revised manuscript.

read point-by-point responses

  1. Referee: [Free-space feasibility analysis (abstract and conclusion)] The feasibility claim for free-space transmission over several tens of meters (stated in the abstract and repeated in the conclusion) rests on analysis of the error-free threshold power but omits a quantitative link budget. No explicit accounting is provided for 300 GHz atmospheric absorption (typically 10-20 dB/km), beam divergence losses, or specific high-gain antenna performance, which directly affects whether the measured threshold supports the stated range.

    Authors: We agree that the original manuscript presented only a high-level projection based on the measured error-free threshold power without an explicit quantitative link budget. This omission limited the strength of the feasibility claim. In the revised manuscript we have added a dedicated paragraph in the discussion section that provides a full link budget. The calculation incorporates: atmospheric absorption of 12–18 dB/km at 300 GHz (using standard ITU models for 50 % relative humidity), free-space path loss via the Friis transmission equation with assumed antenna gains of 45–50 dBi (realizable with compact high-gain horn or lens antennas at THz frequencies), and a conservative 10 dB margin for additional system losses and fading. Using the experimentally determined error-free received-power threshold of approximately −22 dBm together with a 10 dBm output from a typical THz amplifier, the budget shows that line-of-sight distances of 25–50 m remain feasible. We have updated the abstract and conclusion to reference this analysis and to qualify the range as “projected under realistic antenna and amplifier assumptions.” The complete numerical steps are now included in the main text for transparency. revision: yes

Circularity Check

0 steps flagged

No circularity: central claims rest on direct experimental BER measurements

full rationale

The paper's load-bearing result is an experimental demonstration of BER < 10^{-9} at 10 Gbps in a short back-to-back waveguide setup using the SiN soliton comb. The feasibility statement for free-space transmission is an extrapolation from the measured error-free threshold power, not a derivation that reduces by construction to fitted parameters or self-citations. No equations, ansatzes, or uniqueness theorems are invoked that loop back to the inputs; the chain is self-contained experimental data without self-definitional or fitted-input-called-prediction patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The central claim rests on experimental measurements of BER and power thresholds in a controlled waveguide setup plus standard extrapolation for free-space links. No new free parameters, axioms, or invented entities are introduced beyond established photonic and communication principles.

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