# Corrections to "Continuous Phase Modulation Proposal for Photonics-Wireless Sub-THz Transmissions"

Paul Desombre, Haïfa Farès, Yves Louët, Jérôme Taillieu, Laurent Bramerie,
Mathilde Gay, David González Ovejero, Mehdi Alouini

► To cite this version:

Paul Desombre, Haïfa Farès, Yves Louët, Jérôme Taillieu, Laurent Bramerie, et al. Corrections to "Continuous Phase Modulation Proposal for Photonics-Wireless Sub-THz Transmissions". IEEE Access, 2024, 12, pp.176880-176883. 10.1109/access.2024.3502932. hal-05154548

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https://nantes-universite.hal.science/hal-05154548v1

Submitted on 9 Jul 2025

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
Received 18 November 2024, accepted 18 November 2024, date of current version 4 December 2024.

Digital Object Identifier 10.1109/ACCESS.2024.3502932

COMMENTS AND CORRECTIONS

Corrections to “Continuous Phase Modulation
Proposal for Photonics-Wireless
Sub-THz Transmissions”

PAUL DESOMBRE(1,3), (Member, IEEE), HAÏFA FARÈS(1), (Member, IEEE), YVES LOUËT<fnref n="1" />, JÉRÔME TAILLIEU(2,3), (Member, IEEE), LAURENT BRAMERIE<fnref n="2" />, MATHILDE GAY<fnref n="2" />, DAVID GONZÁLEZ OVEJERO(1,3), (Senior Member, IEEE), AND MEHDI ALOUINI<fnref n="2" />

Corresponding author: Paul Desombre (paul.desombre@centralesupelec.fr)

This work was supported in part by French Government granted to the Labex CominLabs Laboratory of Excellence and managed by the National Research Agency within the framework of the “Investments of the Future” Program under Grant ANR-10-LABX-07-01; in part by the European Union through the European Regional Development Fund (ERDF); in part by the Ministry of Higher Education and Research; in part by French National Center for Scientific Research, Brittany Region; in part by the Conseils Départementaux d'Ile-et-Vilaine and Côtes d'Armor, Rennes Métropole; and in part by the Lannion Trégor Communauté, through the CPER Projects CyMoCod and PhotBreizh.

In the above article [1], certain key contributors were inadvertently omitted from the authors' list. Specifically, the colleagues responsible for the measurement aspects in Section V of our study were not included. The following authors were missing.

1) Jérôme Taillieu (CNRS, Institut FOTON, UMR 6082, Université Rennes, 35000 Rennes, France, and CNRS, Institut d'Électronique et des Technologies du numéRique (IETR), UMR 6164, Université Rennes, 35000 Rennes, France)

2) Laurent Bramerie (CNRS, Institut FOTON, UMR 6082, Université Rennes, 35000 Rennes, France)

3) Mathilde Gay (CNRS, Institut FOTON, UMR 6082, Université Rennes, 35000 Rennes, France)

4) David González Ovejero (CNRS, Institut d'Électronique et des Technologies du numéRique (IETR), UMR 6164, Université Rennes, 35000 Rennes, France)

5) Mehdi Alouini (CNRS, Institut FOTON, UMR 6082, Université Rennes, 35000 Rennes, France)

This oversight arose from the initial scope of our
paper. Originally, the primary objective was to propose
a novel approach in the field of digital communications
and signal processing for sub-Terahertz point-to-point links.
As we progressed, however, we decided to include the
measurement results to strengthen the validation of our
proposal.

In doing so, we inadvertently overlooked the fact that
incorporating the measurement data extended beyond our

own intellectual property boundaries. We failed to fully
recognize the significant contributions made by our collab-
orators in this area, which are essential to the integrity and
accuracy of the presented results.

The measurements detailed in [1] could not be the fruit
of one research area. They were, indeed, the result of a
collaborative effort between several teams within two spe-
cialized laboratories and were conducted in the framework
of a consortium project funded by the French Ministry from
2020 to 2024. In particular, these measurements relied on
equipment and expertise in the areas of antenna design, opto-
electronic components, photonics, waveform generation, and
signal processing. Therefore, such a complex and multidis-
ciplinary task could not have been accomplished by a single
group, but rather through the combined expertise of all the
teams involved.

The authors requested this correction to include the authors
missing in [1] and to provide additional details on the exper-
iment description and results in Section V of [1], as detailed
below.

V. SUB-THZ EXPERIMENTATIONS

A. EXPERIMENTAL SETUP

Fig. 12 illustrates our experimental setup. The analog signal
is generated by an Arbitrary Waveform Generator (AWG)
with 88 GSps of sample rate, 25 GHz of analog electrical
bandwidth and 2¹⁴ samples of memory length. One of the
optical wavelengths (λ₁), obtained from an External Cavity
Laser (ECL), is modulated by the output of the AWG using

<footnote n="1">¹IETR, UMR, CNRS, 6164, CentraleSupélec Rennes Campus, 35576 Cesson-Sévigné, France</footnote>

<footnote n="2">²CNRS, Institut FOTON, UMR 6082, Université Rennes, 35000 Rennes, France</footnote>

<footnote n="3">³CNRS, Institut d'Électronique et des Technologies du numéRique (IETR), UMR 6164, Université Rennes, 35000 Rennes, France</footnote>
<figure><img src="image_2.png" /><figcaption>FIGURE 12. Experimental setup for Sub-THz wireless transmission of baseband selected waveforms. a. depicts the photonic front-end of the transmitter, experimental setup for Sub-THz wireless transmission of baseband selected waveforms while b. shows the sub-THz wave generation, propagation, and acquisition on a 100 GSps scope. AWG: Arbitrary Waveform Generator, IQ modulator: In-phase and Quadrature baseband modulator, OSA: Optical Spectrum Analyzer, EDFA: Erbium-Doped Fiber Amplifier, PTFE: Polytetrafluoroethylene, ECL: External Cavity Laser, SHM: Sub-Harmonic Mixer, distance d: wireless communication distance.</figcaption></figure>

an electro-optical IQ modulator. The analog signal from the AWG consists of a waveform designed in the digital domain, as detailed in Table 5. A second ECL, similar to the first one, provides the reference wavelength ($\lambda_2$) necessary for the carrier frequency generation. The frequency difference between the two lasers, defined as $\Delta_f = F_{ECL_2} - F_{ECL_1}$, is set to $\Delta_f = 107.5$ GHz in these experiments. The power imbalance of the two signals is approximately compensated by the 90/10 optical coupler and further fine-tuned by adjusting the pump current of each ECL. One percent of the signal is extracted to monitor the power spectrum, while the remaining 99% is amplified using an Erbium-Doped Fiber Amplifier (EDFA). An attenuator is then used to monitor and adapt the signal power to approximately 12 dBm. Then, the optical signal is transmitted to a commercial TOPTICA (EK-000724) photomixing emitter. This transmitter consists of an ultrabroadband P-i-N photodiode connected to a lens-integrated, vertically-polarized bow-tie antenna [51]. This antenna is placed at the back focal plane of a Teflon lens with a 4" diameter and focal distance of 151 mm (reference LAT 151 from Thorlabs).

On the receiver side, a 20 dBi gain, vertically polarized conical horn antenna operating at W-band is placed at the focal point of a second, identical Teflon lens to capture the radiated power. The output of the horn antenna connects to a standard W-band (75-110 GHz) rectangular waveguide, which is further connected to a Sub-Harmonic Mixer (SHM) from VDI, model WR10SHM. This SHM is fed by a Local Oscillator (LO) generating a 50 GHz tone, obtained using an Anritsu MG3695C signal generator. The tone is further amplified by a broadband amplifier (SHF-804-P) in order to reach the required LO input power of 3 to 6 dBm for the SHM. Thus, the received signal is down-converted to an Intermediate Frequency (IF) of 7.5 GHz. The IF signal is then amplified using a Low-Noise Amplifier (LNA), and the output of the LNA is acquired with an oscilloscope

operating at 100 GSps with an analog bandwidth of 33 GHz. Finally, the collected data is processed offline. The experiment was limited to a short wireless point-to-point link, ranging from 0.2 m to 1.8 m, due to the restricted laboratory space. Due to the availability of the photonic and electronics components the experiment was also constrained to SISO communications.

## B. MEASUREMENTS AT FIXED SNR

The measurement procedure was as follows: first, the waveform was designed in the digital domain and then generated by the AWG. The AWG output modulated an optical carrier, which was subsequently combined with an optical tone at the frequency $F_{ECL_2} = F_{ECL_1} + \Delta_f$. The Radio-Frequency (RF) signal produced by the photodiode was transmitted through the wireless link and then received by the horn antenna. This RF signal was finally down-converted to IF, amplified, and acquired using a sampling oscilloscope. The collected data was then treated offline by custom-made software.

Experimentally, the SNR after quantization and acquisition on the oscilloscope was measured to be between 17 and 23 dB. Several non-ideal experimental conditions contributed to reducing the overall SNR. Specifically, misalignment losses due to difficult antenna alignment [55], as well as non-thermal noise sources (shot noise and scintillation) arising from the photonic and electronic equipment [40], [56], negatively affected the SNR. Additionally, environmental factors played a significant role: measurements were conducted in June 2023 under high laboratory temperatures. The ambient water vapor concentration was also high, with measurements performed at the Platform PERSYST in Lannion, France, where the local weather office indicated an average humidity of 60% and a peak of 99% in June 2023. The atmospheric pressure at the time was 1017.4 hPa. These factors explain the lower-than-expected SNR values compared to theoretical prediction values.
<figure><img src="image_3.png" /><figcaption>FIGURE 13. Normalized PSD of observed waveforms at IF = 7.5 GHz after acquisition on a 33 GHz scope.</figcaption></figure>

Fig. 13 presents the Power Spectral Density (PSD) of the acquired signals, centered at an IF of 7.5 GHz. The blue, red, and purple curves represent the GMSK, QPSK, and RC waveforms, respectively. The significant variations in the received power from 3 to 12 GHz can be attributed to the photomixer's response. As said previously, the sub-THz source consists of a PIN photodiode integrated with a silicon lens, leading to cavity effects within the integrated lens antenna that strongly influence signal transmission. This phenomenon is evident in the gray curve, which represents the normalized power emitted by the integrated lens antenna, shifted to the IF frequency after down-conversion.

The oscillations observed in the out-of-band signal, beyond 12 GHz, for the GMSK waveform are likely caused by a temporary disturbance in the biasing of the IQ modulators. These modulators are highly sensitive to room temperature fluctuations, and this issue went unnoticed during the experiment.

## REFERENCES

[1] P. Desombre, H. Farès, and Y. Louët, "Continuous phase modulation proposal for photonics-wireless sub-THz transmissions," *IEEE Access*, vol. 12, pp. 100217-100229, 2024, doi: 10.1109/ACCESS.2024.3431275.

**JÉRÔME TAILLIEU** (Member, IEEE) was born in Saint-Germain-en-Laye, France, in 1996. He received the M.S. degree in fundamental and applied physics specializing in photonics from the University of Rennes, France, in October 2020. He is currently pursuing the Ph.D. degree with the Institut Foton and the Institut d'Electronique et des Technologies du numérique (IETR), Rennes. His research interests include photonic phased arrays, leaky wave antenna, metasurfaces, optical beam forming networks, near-field and far-field mmWave communications, and active optically controlled transmit arrays.

**LAURENT BRAMERIE** received the Ph.D. degree from CNRS FOTON-ENSSAT, Lannion, France, in 2004. He has worked for two years with Corvis, Lannion, a system vendor making ultra-long haul 10 Gb/s DWDM systems. He was the Technical Expert with Corvis on ultra-long haul 40 Gb/s DWDM systems. In 2003, he was hired with the FOTON (CNRS Unity) to work on the PERSYST platform which is a public research and test facility offering a testbed for optical telecommunications systems open to private companies and university teams. He is the co-author of more than 80 publications in peer-reviewed international journals and 153 contributions in peer-reviewed international conferences.

**MATHILDE GAY** received the Ph.D. degree from the Institut National des Sciences Appliquées, in 2006, on the investigation of the impact of optical regeneration on high bit rate optical transmission systems at 10 and 40 Gbit/s. She is currently a CNRS Research Engineer with the Institut FOTON and leads the PERSYST platform for test and research in optical communication. She is the author or co-author of more than 100 international articles.

**DAVID GONZÁLEZ OVEJERO** (Senior Member, IEEE) received the M.Sc. degree in telecommunication engineering from the Universidad Politécnica de Valencia, Spain, in 2005, the Ph.D. degree in electrical engineering from the Université Catholique de Louvain, Belgium, in 2012, and the Habilitation à Diriger des Recherches degree from the Université de Rennes, France, in 2024.

From 2012 to 2014, he was a Research Associate with the University of Siena, Siena, Italy. In 2014, he joined the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, where he was a Marie Curie Postdoctoral Fellow. Since 2016, he has been a tenured Researcher with French National Center for Scientific Research (CNRS), Institut d'Electronique et des Technologies du numérique (IETR), Rennes, France. His current research interests include computational electromagnetics, large phased arrays, periodic structures, metasurfaces, and submillimeter-wave antennas. He was awarded a Marie Curie International Outgoing Fellowship from the European Commission, in 2013, the Sergei A. Schelkunoff Transactions Prize Paper Award from the IEEE Antennas and Propagation Society, in 2016, the Best Paper Award in Antenna Design and Applications from the 11th European Conference on Antennas and Propagation, in 2017, the Best Paper Award in Electromagnetics from the 15th European Conference on Antennas and Propagation, in 2021, and the Best Paper Award from the International Workshop on Antenna Technology (iWAT), in 2023. Since 2019, he has been an Associate Editor of IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION and IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY.

**MEHDI ALOUINI** received the M.S. degree in optics and photonics from the Ecole Supérieure d'Optique, University of Paris XI, Orsay, France, in 1997, and the Ph.D. degree in laser physics from the University of Rennes 1, France, in 2001. He was a Research Scientist with Thales Research and Technology, Palaiseau, France, from 2001 to 2009. Since then, he joined the University of Rennes 1, as an Associate Professor, and then as a Full Professor where he led, up to 2017, the Optics and Photonics Department, Institut de Physique de Rennes. He was a Scientific Advisor with Thales, from 2008 to 2019. He is currently the Director of the Institut Foton. His research activities cover laser physics, microwave photonics, and advanced imaging.
**JÉRÔME TAILLIEU** (Member, IEEE) was born in Saint-Germain-en-Laye, France, in 1996. He received the M.S. degree in fundamental and applied physics specializing in photonics from the University of Rennes, France, in October 2020. He is currently pursuing the Ph.D. degree with the Institut Foton and the Institut d'Electronique et des Technologies du numérique (IETR), Rennes. His research interests include photonic phased arrays, leaky wave antenna, metasurfaces, optical beam forming networks, near-field and far-field mmWave communications, and active optically controlled transmit arrays.

**LAURENT BRAMERIE** received the Ph.D. degree from CNRS FOTON-ENSSAT, Lannion, France, in 2004. He has worked for two years with Corvis, Lannion, a system vendor making ultra-long haul 10 Gb/s DWDM systems. He was the Technical Expert with Corvis on ultra-long haul 40 Gb/s DWDM systems. In 2003, he was hired with the FOTON (CNRS Unity) to work on the PERSYST platform which is a public research and test facility offering a testbed for optical telecommunications systems open to private companies and university teams. He is the co-author of more than 80 publications in peer-reviewed international journals and 153 contributions in peer-reviewed international conferences.

**MATHILDE GAY** received the Ph.D. degree from the Institut National des Sciences Appliquées, in 2006, on the investigation of the impact of optical regeneration on high bit rate optical transmission systems at 10 and 40 Gbit/s. She is currently a CNRS Research Engineer with the Institut FOTON and leads the PERSYST platform for test and research in optical communication. She is the author or co-author of more than 100 international articles.

**DAVID GONZÁLEZ OVEJERO** (Senior Member, IEEE) received the M.Sc. degree in telecommunication engineering from the Universidad Politécnica de Valencia, Spain, in 2005, the Ph.D. degree in electrical engineering from the Université Catholique de Louvain, Belgium, in 2012, and the Habilitation à Diriger des Recherches degree from the Université de Rennes, France, in 2024.

From 2012 to 2014, he was a Research Associate with the University of Siena, Siena, Italy. In 2014, he joined the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, where he was a Marie Curie Postdoctoral Fellow. Since 2016, he has been a tenured Researcher with French National Center for Scientific Research (CNRS), Institut d'Electronique et des Technologies du numérique (IETR), Rennes, France. His current research interests include computational electromagnetics, large phased arrays, periodic structures, metasurfaces, and submillimeter-wave antennas. He was awarded a Marie Curie International Outgoing Fellowship from the European Commission, in 2013, the Sergei A. Schelkunoff Transactions Prize Paper Award from the IEEE Antennas and Propagation Society, in 2016, the Best Paper Award in Antenna Design and Applications from the 11th European Conference on Antennas and Propagation, in 2017, the Best Paper Award in Electromagnetics from the 15th European Conference on Antennas and Propagation, in 2021, and the Best Paper Award from the International Workshop on Antenna Technology (iWAT), in 2023. Since 2019, he has been an Associate Editor of IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION and IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY.

**MEHDI ALOUINI** received the M.S. degree in optics and photonics from the Ecole Supérieure d'Optique, University of Paris XI, Orsay, France, in 1997, and the Ph.D. degree in laser physics from the University of Rennes 1, France, in 2001. He was a Research Scientist with Thales Research and Technology, Palaiseau, France, from 2001 to 2009. Since then, he joined the University of Rennes 1, as an Associate Professor, and then as a Full Professor where he led, up to 2017, the Optics and Photonics Department, Institut de Physique de Rennes. He was a Scientific Advisor with Thales, from 2008 to 2019. He is currently the Director of the Institut Foton. His research activities cover laser physics, microwave photonics, and advanced imaging.

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