| 1. |
- Borkowski, R., et al.
(författare)
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Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers
- 2014
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Ingår i: Optical Fiber Technology. - : Elsevier BV. - 1095-9912 .- 1068-5200. ; 20:2, s. 158-162
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Tidskriftsartikel (refereegranskat)abstract
- We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) and against differential group delay (DGD) in an experiment involving 112 Gbit/s polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16 QAM) and quaternary phase-shift keying (QPSK).
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| 2. |
- Brajato, Giovanni, et al.
(författare)
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Bayesian filtering framework for noise characterization of frequency combs
- 2020
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 28:9, s. 13949-13964
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Tidskriftsartikel (refereegranskat)abstract
- Amplitude and phase noise correlation matrices are of fundamental importance for studying noise properties of frequency combs. They include information about the origin of noise sources as well as the scaling and correlation of the noise across the comb lines. These matrices provide an insight that is essential for obtaining low-noise performance which is important for, e.g., applications in optical communication, low–noise microwave signal generation, and distance measurements. Estimation of amplitude and phase noise correlation matrices requires highly–accurate measurement technique which can distinguishes between noise sources coming from the frequency comb and the measurement system itself. Bayesian filtering provides a theoretically optimum approach for filtering of measurement noise and thereby, the most accurate measurement of phase and amplitude noise. In this paper, a novel Bayesian filtering based framework for joint estimation of amplitude and phase noise of multiple frequency comb lines is proposed, and demonstrated for phase noise characterization. Compared to the conventional approaches, that do not employ any measurement noise filtering, the proposed approach provides significantly more accurate measurements of correlation matrices, operates over a wide range of signal–to–noise–ratios and gives an insight into comb’s dynamics at short scales (<10−8 s). © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 3. |
- Brajato, Giovanni, et al.
(författare)
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Optical frequency comb noise characterization using machine learning
- 2019
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Ingår i: IET Conference Publications. ; 2019:CP765
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Konferensbidrag (refereegranskat)abstract
- A novel tool, based on Bayesian filtering framework and expectation maximization algorithm, is numerically and experimentally demonstrated for accurate frequency comb noise characterization. The tool is statistically optimum in a mean-square-error-sense, works at wide range of SNRs and offers more accurate noise estimation compared to conventional methods.
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| 4. |
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| 5. |
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| 6. |
- Leong, Miu Yoong, et al.
(författare)
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BCH Codes for Coherent Star DQAM Systems with Laser Phase Noise
- 2017
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Ingår i: Journal of optical communications. - : Walter de Gruyter. - 0173-4911 .- 2191-6322. ; 38:1, s. 47-56
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Tidskriftsartikel (refereegranskat)abstract
- Coherent optical systems have relatively high laser phase noise, which affects the performance of forward error correction (FEC) codes. In this paper, we propose a method for selecting Bose-Chaudhuri-Hocquenghem (BCH) codes for coherent systems with star-shaped constellations and M-ary differential quadrature amplitude modulation (DQAM). Our method supports constellations of any order M which is a power of 2, and includes differential M-ary phase shift keying as a special case. Our approach is straightforward, requiring only short pre-FEC simulations to parameterize a statistical model, based on which we select codes analytically. It is applicable to pre-FEC bit error rates (BERs) of around 10-3. We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of 10-5, codes selected with our method yield BERs within 2× target. Lastly, we extend our method to systems with interleaving, which enables us to use codes with lower overhead.
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| 7. |
- Leong, Miu Yoong, et al.
(författare)
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Dimensioning RS codes for mitigation of phase noise induced cycle slips in DQPSK systems
- 2014
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Ingår i: Asia Communications and Photonics Conference, ACP. - Washington, D.C. : Optical Society of America. - 9781557528520
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Konferensbidrag (refereegranskat)abstract
- We present a semi-analytical method for dimensioning Reed-Solomon codes for coherent DQPSK systems with laser phase noise and cycle slips. We evaluate the accuracy of our method for a 28 Gbaud system using numerical simulations.
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| 8. |
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| 9. |
- Navarro, Jaime Rodrigo, et al.
(författare)
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Phase noise tolerant carrier recovery scheme for 28 Gbaud circular 16QAM
- 2015
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Ingår i: European Conference on Optical Communication, ECOC. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788460817413
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Konferensbidrag (refereegranskat)abstract
- We propose a novel carrier phase recovery scheme for circular 16QAM coherent transmission systems. Experimental results show low penalties (<1.4 dB) even for linewidths where square 16QAM exhibits irretrievable (above the FEC limit) error floor.
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| 10. |
- Olmedo, Miguel Iglesias, et al.
(författare)
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Carrier recovery techniques for semiconductor laser frequency noise for 28 Gbd DP-16QAM
- 2015
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Ingår i: Optical Fiber Communication Conference, OFC 2015. - Washington, D.C. : IEEE. - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- We report on the first experimental comparison of DD-PLL, two-stage feed forward, and two variations of extended Kalman filtering for tracking semiconductor laser frequency noise. We identify which carrier phase recovery technique works best depending on the carrier induced frequency noise profile.
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| 11. |
- Oxenløwe, L. K., et al.
(författare)
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100s gigabit/s THz communication
- 2018
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- This paper gives an overview of recent progress on the topic of using around 0.4 THz carriers for communications. Experimental demonstrations will be described, and concepts and pros & cons of various system-platforms discussed.
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| 12. |
- Pang, Xiaodan, Dr., et al.
(författare)
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260 Gbit/s Photonic-Wireless Link in the THz Band
- 2016
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Ingår i: 260 Gbit/s photonic-wireless link in the THz band. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509019069
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Konferensbidrag (refereegranskat)abstract
- A single-transmitter/single-receiver THz link (0.3-0.5 THz) with a record net data rate of 260 Gbit/s is experimentally demonstrated. Spectrally efficient multi-channel signal transmission is enabled by a novel frequency-band-allocation scheme with pre-and-post-digital equalization.
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| 13. |
- Pang, Xiaodan, et al.
(författare)
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Experimental Study of 1.55-μ m EML-Based Optical IM/DD PAM-4/8 Short Reach Systems
- 2017
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1041-1135 .- 1941-0174. ; 29:6, s. 523-526
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally evaluate high-speed intensity modulation/direct detection (IM/DD) transmissions with a 1.55-μ text broadband electro-Absorption modulated laser and pulse amplitude modulations (PAM). We demonstrate 80 Gb/s/ λ PAM-4 and 96 Gb/s/ λ PAM-8 transmissions with low-complexity digital equalizers at the receiver. Performance comparison with different types of equalizers are performed, including linear symbol-spaced feed-forward equalizer (FFE), fractional (half-symbol) spaced FFE and decision feedback equalizer (DFE), with different tap number. It is found that for both cases, a 6-Tap symbol-spaced FFE is sufficient to achieve a stable performance with bit-error-rate below the 7% overhead hard decision forward error correction (7%-OH HD-FEC) threshold over a 4 km standard single mode fiber link. Practical considerations including comparison between adaptive and static equalizer implementation and tolerable fiber chromatic dispersion are discussed.
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| 14. |
- Piels, M., et al.
(författare)
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Rate equation-based phase recovery for semiconductor laser coherent transmitters
- 2015
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Ingår i: Optical Fiber Communication Conference, OFC 2015. - Washington, D.C. : OSA - The Optical Society. - 9781557529374
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Konferensbidrag (refereegranskat)abstract
- We present a novel carrier recovery technique for coherent systems with semiconductor lasers that incorporates the laser dynamics. A sensitivity improvement of 8dB over a decisiondirected phase-locked loop is achieved experimentally for 28GBd DP-16QAM.
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| 15. |
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| 16. |
- Srinivasan, Muralikrishnan, 1991, et al.
(författare)
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End-to-End Learning for VCSEL-based Optical Interconnects: State-of-the-Art, Challenges, and Opportunities
- 2023
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 41:11, s. 3261-3277
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Tidskriftsartikel (refereegranskat)abstract
- Optical interconnects (OIs) based on vertical-cavity surface-emitting lasers (VCSELs) are the main workhorse within data centers, supercomputers, and even vehicles, providing low-cost, high-rate connectivity. VCSELs must operate under extremely harsh and time-varying conditions, thus requiring adaptive and flexible designs of the communication chain. Such designs can be built based on mathematical models (model-based design) or learned from data (machine learning (ML) based design). Various ML techniques have recently come to the forefront, replacing individual components in the transmitters and receivers with deep neural networks. Beyond such component-wise learning, end-to-end (E2E) autoencoder approaches can reach the ultimate performance through co-optimizing entire parameterized transmitters and receivers. This tutorial paper aims to provide an overview of ML for VCSEL-based OIs, with a focus on E2E approaches, dealing specifically with the unique challenges facing VCSELs, such as the wide temperature variations and complex models.
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| 17. |
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| 18. |
- Zibar, D., et al.
(författare)
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Machine learning under the spotlight
- 2017
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 11:12, s. 749-751
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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