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Wang, Z., Zhang, L., Fang, X., Ran, W., Pang, X., Ozolins, O. & Yu, X. (2025). AWGR-based fiber-wireless converged networks: scalable resource management and THz-range agility for broadband access. Optics Express, 33(19), 40504-40519
Open this publication in new window or tab >>AWGR-based fiber-wireless converged networks: scalable resource management and THz-range agility for broadband access
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2025 (English)In: Optics Express, E-ISSN 1094-4087, Vol. 33, no 19, p. 40504-40519Article in journal (Refereed) Published
Abstract [en]

Next-generation communication networks require the integration of traditional and high-frequency bands to support diverse applications, positioning the optical heterodyne approach as a promising candidate for remote radio head (RRH) signal generation. However, deploying point-to-point (PtP) analog links based on such an optical heterodyne approach for the radio access networks (RAN) is challenging. Particularly, widespread deployment is expected to be hindered by practical communication resource constraints. In this context, we propose an arrayed waveguide grating router (AWGR)-based RAN architecture incorporating optical heterodyne signal generation, enabling adaptive frequency adjustment and scalable resource management. We detail the architecture and establish its generalizability through mathematical derivation. For a representative 64×64 AWGR-based system, the proposed architecture could reduce the required number of local oscillator (LO) lasers to 1/8 of conventional approaches, with potential for further reduction via scheduling. Experimental validation at both 28 GHz (mmWave) and 286 GHz (THz) bands demonstrates physical feasibility, achieving bit-error rates (BER) of 3.06×10−5 and 1.53×10−4, respectively. This AWGR-based architecture offers a practical path towards resource-efficient, high-agility fiber-wireless converged access.

Place, publisher, year, edition, pages
Optica Publishing Group (formerly OSA), 2025
Keywords
Adaptive optics, Arrayed waveguide gratings, Bit error rate, Computer architecture, Fiber optic networks, Natural resources management, Network architecture, Next generation networks, Optical fiber communication, Resource allocation, Routers, Arrayed wave guide grating, Broadband access, Converged networks, Fiberwireless (FiWi), Next generation communication network, Optical-, Radio access networks, Resource management, Signal generation, Waveguide grating router, Optical heterodyning
National Category
Telecommunications
Identifiers
urn:nbn:se:ri:diva-79384 (URN)10.1364/OE.570336 (DOI)2-s2.0-105017960986 (Scopus ID)
Note

Article; Granskad

Available from: 2025-12-05 Created: 2025-12-05 Last updated: 2025-12-05
Ostrovskis, A., Szczerba, K., Salgals, T., Norberg, E., Koenigsmann, M., Sonkoly, J., . . . Ozoliņš, O. (2025). Heterogeneously Integrated InP Electro-Absorption Modulator for Beyond 300 Gb/s Optical Links. Journal of Lightwave Technology, 43(4), 1826-1836
Open this publication in new window or tab >>Heterogeneously Integrated InP Electro-Absorption Modulator for Beyond 300 Gb/s Optical Links
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2025 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 43, no 4, p. 1826-1836Article in journal (Refereed) Published
Abstract [en]

The recent AI boom requires more focus on energy-efficient and scalable optical interconnects. Silicon Photonics is enabling technology to satisfy growing demand. However, the lack of lasers and high-performance modulators hinders wide-scale adoption. Therefore, we present a heterogeneously integrated Indium Phosphide electro-absorption modulator with Silicon waveguides. We demonstrate up to 256 Gb/s on-off keying, 340 Gb/s 4-level pulse amplitude modulation, 375 Gb/s 6-level pulse amplitude modulation, and 360 Gb/s 8-level pulse amplitude modulation transmission over 500 m and 6 km of single-mode fiber with performance satisfying requirements of 6.25% overhead hard-decision forward error correction threshold of 4.5×10-3. Additionally, we investigate the modulator at 200 Gb/s per lane scenarios, demonstrating excellent performance with a simple seven-tap feed-forward equalizer.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2025
Keywords
200 Gb/s per lane, electro-absorption modulator, heterogeneous integration, optical interconnects, silicon photonics, Chirp modulation, Forward error correction, Light modulation, Light modulators, Optical fiber communication, Optical heterodyning, Optical links, Optical signal processing, Photonic integrated circuits, Photonic integration technology, Pulse amplitude modulation, Pulse code modulation links, Semiconducting indium phosphide, Signal modulation, Silicon on insulator technology, Silicon wafers, 200a gb/s per lane, Electroabsorption modulator(EAM), Energy efficient, InP, Optical interconnect, Optical-, Performance, Pulse amplitude, Single mode fibers
National Category
Telecommunications Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:ri:diva-79502 (URN)10.1109/JLT.2025.3526822 (DOI)2-s2.0-85214878866 (Scopus ID)
Note

Article; Granskad

Available from: 2025-12-03 Created: 2025-12-03 Last updated: 2025-12-03Bibliographically approved
Ostrovskis, A., Salgals, T., Koenigsmann, M., Marinins, A., Rubuls, K., Krueger, B., . . . Ozoliņš, O. (2025). High-speed silicon photonics ring-resonator modulators for optical-amplification-free links. Optics Express, 33(17), 36758-36769
Open this publication in new window or tab >>High-speed silicon photonics ring-resonator modulators for optical-amplification-free links
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2025 (English)In: Optics Express, E-ISSN 1094-4087, Vol. 33, no 17, p. 36758-36769Article in journal (Refereed) Published
Abstract [en]

Unprecedented demand for energy-efficient optical interconnects in AI clusters requires scalable and small footprint solutions. Silicon photonics platform has emerged as scalable cost-effective solution for short-reach optical interconnects. In this paper, we report record optical-amplification free performance using our designed silicon photonics C + L band and O band ring-resonator modulators suitable for high energy-efficiency optical interconnects. We demonstrate optical-amplification-free transmission of up to 245 Gbps OOK, 280 Gbps PAM4 and 265 Gbps PAM6 using C + L band RRM and up to 206 Gbps OOK and 224 Gbps PAM4 using O band RRM. The achieved speeds are shown as gross bitrate. This paves way for energy-efficient dense optical interconnects with great manufacturing scalability.

Place, publisher, year, edition, pages
Optica Publishing Group (formerly OSA), 2025
Keywords
Amplification, Cost effectiveness, Integrated circuit interconnects, Light modulators, Light transmission, Optical communication, Optical interconnects, Optical resonators, Optical signal processing, Optical systems, Photonic devices, Pulse amplitude modulation, Cost-effective solutions, Energy efficient, High Speed, Optical amplifications, Optical interconnect, Performance, Ring resonator, Silicon photonics, Small footprints, Unprecedented demand, silicon, article, human, optics, photonics, velocity
National Category
Telecommunications Communication Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-79408 (URN)10.1364/OE.570067 (DOI)2-s2.0-105014140856 (Scopus ID)
Note

Article; Granskad

Available from: 2025-12-01 Created: 2025-12-01 Last updated: 2025-12-01Bibliographically approved
Ostrovskis, A., Cirjulina, D., Salgals, T., Koenigsmann, M., Krueger, B., Pittalà, F., . . . Ozolins, O. (2025). Net 300 Gb/s Unamplified Transmission using a Differential Drive SiP TW-MZM. In: IEEE Int. Conf. Group IV Photonics, GFP: . Paper presented at IEEE International Conference on Group IV Photonics GFP. IEEE Computer Society
Open this publication in new window or tab >>Net 300 Gb/s Unamplified Transmission using a Differential Drive SiP TW-MZM
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2025 (English)In: IEEE Int. Conf. Group IV Photonics, GFP, IEEE Computer Society , 2025Conference paper, Published paper (Refereed)
Abstract [en]

We demonstrate record unamplified transmissions of 256 Gbaud OOK, 155 Gbaud PAM4 and 128 Gbaud PAM6 using a C-band differential-drive SiP TW-MZM, achieving BER performance below the 6.25% HD-FEC threshold after 100 m SMF transmission.

Place, publisher, year, edition, pages
IEEE Computer Society, 2025
Keywords
Mach-Zehnder modulator, optical amplification free, Silicon Photonics, Fiber to the x, Light modulation, Light modulators, Optical signal processing, BER performance, C-bands, Differential drive, Mach Zehnder modulator, Optical amplifications
National Category
Telecommunications
Identifiers
urn:nbn:se:ri:diva-79290 (URN)10.1109/SiPhotonics64386.2025.10985216 (DOI)2-s2.0-105005830649 (Scopus ID)
Conference
IEEE International Conference on Group IV Photonics GFP
Note

Conference paper; Granskad

Available from: 2025-11-28 Created: 2025-11-28 Last updated: 2025-11-28
Ostrovskis, A., El-Busaidy, S., Salgals, T., Koenigsmann, M., Rubuls, K., Krueger, B., . . . Ozoliņš, O. (2025). Optical Amplification-Free 400 Gbps Net Bitrate Links with a TFLN-based Transmitter. In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc.: . Paper presented at 2025 Optical Fiber Communications Conference and Exhibition, OFC 2025. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Optical Amplification-Free 400 Gbps Net Bitrate Links with a TFLN-based Transmitter
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2025 (English)In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc., Institute of Electrical and Electronics Engineers Inc. , 2025Conference paper, Published paper (Refereed)
Abstract [en]

We show a record optical amplification-free 400 Gbps PAM4/6/8 net bitrate transmission in the O-band over 500-meter SMF with performance below 6.25% OH HD-FEC threshold using 1 V<inf>pp</inf> driving voltage on the TFLN MZM.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2025
Keywords
Amplification, Digital television, Fiber optics, Light transmission, Optical fiber communication, Optical links, Photonics, Samarium compounds, Transmitters, Bit rates, Bit-rate transmission, Driving voltages, Optical amplifications, Performance, Optical fibers
National Category
Telecommunications Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:ri:diva-79925 (URN)10.1364/OFC.2025.M1G.1 (DOI)2-s2.0-105011345238 (Scopus ID)9781557527370 (ISBN)
Conference
2025 Optical Fiber Communications Conference and Exhibition, OFC 2025
Note

Conference paper; Granskad

Available from: 2025-12-04 Created: 2025-12-04 Last updated: 2025-12-04Bibliographically approved
Lyu, Z., Zhang, L., Deng, Q., Fang, X., Bai, L., Ozoliņš, O., . . . Yu, X. (2025). Photonic Chirp Spread Spectrum THz-ISAC: Constraints and Design Considerations. IEEE transactions on microwave theory and techniques
Open this publication in new window or tab >>Photonic Chirp Spread Spectrum THz-ISAC: Constraints and Design Considerations
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2025 (English)In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670Article in journal (Refereed) Published
Abstract [en]

The photonic terahertz integrated sensing and communication (THz-ISAC) holds immense potential for enabling ultrahigh data rates and millimeter-resolution sensing, due to its exceptionally broad bandwidth. Nevertheless, the limited radiation power of existing THz sources restricts the full utilization of their broadband advantages in single-channel ISAC systems. In this work, a photonic THz-ISAC system model utilizing the chirp spread spectrum (CSS) waveform scheme is proposed and theoretically analyzed, by considering the noise contribution of the photonic THz transceiver and the free-space propagation loss (FSPL). Based on the proposed waveform, we derive the closed form of communication error vector magnitude (EVM) and radar sensing Cramér–Rao lower bound (CRLB), as well as the performance bounds. Then, a proof-of-concept experiment operating at 285 GHz is conducted to verify the performance of the CSS waveform, achieving 12 Gbit/s transmission with a 1.5 cm range resolution. In addition, the experiment validates the performance trade-offs among chirp bandwidth, data rate, and signal power, aligning well with our theoretical bounds. Therefore, the proposed scheme provides a design guideline for CSS-based photonic THz-ISAC systems.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2025
Keywords
Chirp spread spectrum (CSS), integrated sensing and communication (ISAC), terahertz (THz) photonics, Bandwidth, Chirp modulation, Optical communication, Photonics, Spread spectrum communication, Terahertz waves, Chirp spread spectrum, Communications systems, Data-rate, Integrated sensing, Integrated sensing and communication, Sensing systems, Tera Hertz, Terahertz photonics, Waveforms, Economic and social effects
National Category
Telecommunications Other Electrical Engineering, Electronic Engineering, Information Engineering Communication Systems
Identifiers
urn:nbn:se:ri:diva-79905 (URN)10.1109/TMTT.2025.3615239 (DOI)2-s2.0-105020691622 (Scopus ID)
Note

Article; Granskad

Available from: 2025-12-04 Created: 2025-12-04 Last updated: 2025-12-04Bibliographically approved
Deng, Q., Zhang, L., Yang, Z., Lyu, Z., Bobrovs, V., Pang, X., . . . Yu, X. (2025). Photonic Terahertz Chaos Enabling High-Precision and Unambiguous Ranging. Laser & Photonics reviews, Article ID 2400667.
Open this publication in new window or tab >>Photonic Terahertz Chaos Enabling High-Precision and Unambiguous Ranging
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2025 (English)In: Laser & Photonics reviews, ISSN 1863-8880, E-ISSN 1863-8899, article id 2400667Article in journal (Refereed) Epub ahead of print
Abstract [en]

Terahertz (THz, 0.3–10 THz) radar systems have garnered significant attention due to their superior capabilities in high-precision and robust sensing. However, the susceptibility to jamming, along with the sensing precision loss and ranging ambiguity induced by inflexible implementation of the conventional radar signal source, presents major challenges to the practical deployment of THz radars. Herein, a flexible photonic chaotic radar system is proposed at the THz band and investigate the ranging performance in precision and ambiguity. The photonic heterodyne detection scheme facilitates the generation of optoelectronic feedback loop-based THz chaos at 300 GHz, achieving a seamless connection between THz domains and optical domains. The system is experimentally demonstrated its superior performance of sub-centimeter resolution with 0.9345 cm and ranging unambiguity simultaneously. This work bridges the THz gap in the practical deployment of chaos theory and will pave the way for a new regime of THz radar empowered by chaos.

Place, publisher, year, edition, pages
John Wiley and Sons Inc, 2025
National Category
Physical Sciences
Identifiers
urn:nbn:se:ri:diva-78076 (URN)10.1002/lpor.202400667 (DOI)2-s2.0-85215098121 (Scopus ID)
Note

The work was supported bythe National Key Research and Development Program of China undergrant 2022YFB2903800, Natural National Science Foundation of China under grant 62101483, Vetenskapsrådet under grant no. 2022-04798, and theLZP FLPP project “MIR FAST” under grant no. lzp 2023/1-0503.

Available from: 2025-03-24 Created: 2025-03-24 Last updated: 2025-09-23Bibliographically approved
Zhang, L., Lyu, Z., Ozoliņš, O., Pang, X. & Yu, X. (2025). Photonic Terahertz Integrated Sensing and Communication (ISAC) Systems. In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc.: . Paper presented at 2025 Optical Fiber Communications Conference and Exhibition, OFC 2025. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Photonic Terahertz Integrated Sensing and Communication (ISAC) Systems
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2025 (English)In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc., Institute of Electrical and Electronics Engineers Inc. , 2025Conference paper, Published paper (Refereed)
Abstract [en]

This paper explores the role of photonic terahertz technologies in integrated sensing and communication systems, focusing on integrated waveform design, optical processing, and algorithms to enhance communication capabilities and sensing performance.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2025
Keywords
Optical data processing, Optical fiber communication, Photonic integrated circuits, Photonics, Communication capabilities, Communications systems, Integrated sensing, Optical algorithms, Optical processing, Sensing performance, Sensing systems, Tera Hertz, Terahertz technology, Waveform designs, Photonic integration technology
National Category
Communication Systems Other Electrical Engineering, Electronic Engineering, Information Engineering Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:ri:diva-79924 (URN)10.1364/OFC.2025.W4F.6 (DOI)2-s2.0-105011346177 (Scopus ID)
Conference
2025 Optical Fiber Communications Conference and Exhibition, OFC 2025
Note

Conference paper; Granskad

Available from: 2025-12-04 Created: 2025-12-04 Last updated: 2025-12-04Bibliographically approved
Puerta, R., Jiang, T., Rubuls, K., Li, D., Joharifar, M., Ostrovskis, A., . . . Pang, X. (2025). Toward 6G: Analog Fronthaul Solutions for Mobile Networks. In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc.: . Paper presented at 2025 Optical Fiber Communications Conference and Exhibition, OFC 2025. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Toward 6G: Analog Fronthaul Solutions for Mobile Networks
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2025 (English)In: Opt. Fiber Commun. Conf. Exhib., OFC - Proc., Institute of Electrical and Electronics Engineers Inc. , 2025Conference paper, Published paper (Refereed)
Abstract [en]

This paper explores photonic-based analog fronthaul solutions for 6G, highlighting their effectiveness in meeting the RF requirements of standards, supporting future distributed-MIMO networks, and providing insights into prospective solutions for radios in potential 6G bands.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2025
Keywords
MIMO systems, Mobile telecommunication systems, Photonics, Distributed MIMO, MIMO networks, Prospectives, Wireless networks
National Category
Telecommunications Communication Systems
Identifiers
urn:nbn:se:ri:diva-79923 (URN)10.1364/OFC.2025.W3I.4 (DOI)2-s2.0-105011359941 (Scopus ID)
Conference
2025 Optical Fiber Communications Conference and Exhibition, OFC 2025
Note

Conference paper; Granskad

Available from: 2025-12-04 Created: 2025-12-04 Last updated: 2025-12-04Bibliographically approved
Xi, R., Zhang, L., Bobrovs, V., Ozolins, O., Pang, X. & Yu, X. (2025). Transfer learning based adaptive entropy loading for radio-over-fiber systems. Optics Express, 33(4), 6674-6688
Open this publication in new window or tab >>Transfer learning based adaptive entropy loading for radio-over-fiber systems
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2025 (English)In: Optics Express, E-ISSN 1094-4087, Vol. 33, no 4, p. 6674-6688Article in journal (Refereed) Published
Abstract [en]

The radio-over-fiber (RoF) system is promising to support broadband transmission and increased flexibility. To boost channel capacity in multi-carrier RoF systems with variable-rate forward error correction, probabilistic shaping and water-filling-based entropy loading outperforms bit-power loading in terms of achievable information rate. However, its reliance on specific channel conditions limits practical use in channel-dynamic RoF systems, highlighting the need for adaptive entropy loading that requires minimal channel state information. This paper presents a deep neural network-based transfer learning model for adaptive entropy prediction in discrete multi-tone signals, addressing frequency-selective responses in RoF systems. Numerical and experimental results confirm capacity-approaching generalized mutual information (GMI) and smoother normalized GMI (NGMI) performances, consistently achieving the 0.83 NGMI threshold across subcarriers. Unlike traditional methods requiring pre-measured signal-to-noise ratios (SNR), this approach simplifies implementation by using only demodulated data and the received SNR, providing a more channel-independent entropy loading option in dynamic RoF systems. 

Place, publisher, year, edition, pages
Optica Publishing Group (formerly OSA), 2025
Keywords
Adaptive optics; Bit error rate; Forward error correction; Radio transmission; Radio-over-fiber; Broadband transmission; Channel’s capacity; Increased flexibility; Multicarriers; Mutual informations; Noise ratio; Radio over fiber system; Signal to noise; Transfer learning; Transmission flexibility; Signal to noise ratio
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-78393 (URN)10.1364/OE.546997 (DOI)2-s2.0-85219039160 (Scopus ID)
Note

Key Research and Development Program of Zhejiang Province (2023C01139); National Natural Science Foundation of China (62471433); VINNOVA (2024-02451); the Strategic Innovation Program Smarter Electronic Systems - a joint venture by Vinnova, Formas and the Swedish Energy Agency A-FRONTAHUL project (2023-00659).

Available from: 2025-09-19 Created: 2025-09-19 Last updated: 2025-09-23Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4906-1704

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