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Publications (10 of 148) Show all publications
Zhang, L., Hong, X., Pang, X., Ozolins, O., Udalcovs, A., Schatz, R., . . . Chen, J. (2018). Nonlinearity-aware 200 Gbit/s DMT transmission for C-band short-reach optical interconnects with a single packaged electro-absorption modulated laser. Optics Letters, 43(2), 182-185.
Open this publication in new window or tab >>Nonlinearity-aware 200 Gbit/s DMT transmission for C-band short-reach optical interconnects with a single packaged electro-absorption modulated laser
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2018 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 2, p. 182-185Article in journal (Refereed) Published
Abstract [en]

We experimentally demonstrate the transmission of a 200 Gbit/s discrete multitone (DMT) at the soft forward error correction limit in an intensity-modulation directdetection system with a single C-band packaged distributed feedback laser and traveling-wave electro absorption modulator (DFB-TWEAM), digital-to-analog converter and photodiode. The bit-power loaded DMT signal is transmitted over 1.6 km standard single-mode fiber with a net rate of 166.7 Gbit/s, achieving an effective electrical spectrum efficiency of 4.93 bit/s/Hz. Meanwhile, net rates of 174.2 Gbit/s and 179.5 Gbit/s are also demonstrated over 0.8 km SSMF and in an optical back-to-back case, respectively. The feature of the packaged DFB-TWEAM is presented. The nonlinearity-aware digital signal processing algorithm for channel equalization is mathematically described, which improves the signal-to-noise ratio up to 3.5 dB. 

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-221927 (URN)10.1364/OL.43.000182 (DOI)000422801600005 ()29328233 (PubMedID)2-s2.0-85040313909 (Scopus ID)
Note

QC 20180130

Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-02-02Bibliographically approved
Ozolins, O., Pang, X., Iglesias Olmedo, M., Kakkar, A., Udalcovs, A., Gaiarin, S., . . . Jacobsen, G. (2017). 100 GHz Externally Modulated Laser for Optical Interconnects. Journal of Lightwave Technology, 35(6), 1174-1179.
Open this publication in new window or tab >>100 GHz Externally Modulated Laser for Optical Interconnects
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2017 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, no 6, p. 1174-1179Article in journal (Refereed) Published
Abstract [en]

We report on a 116 Gb/s on-off keying (OOK), four pulse amplitude modulation (PAM) and 105-Gb/s 8-PAM optical transmitter using an InP-based integrated and packaged externally modulated laser for high-speed optical interconnects with up to 30 dB static extinction ratio and over 100-GHz 3-dB bandwidth with 2 dB ripple. In addition, we study the tradeoff between power penalty and equalizer length to foresee transmission distances with standard single mode fiber.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
Keyword
Direct detection, distributed feedback laser (DFB), electroabsorption modulator, optical interconnects
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-206702 (URN)10.1109/JLT.2017.2651947 (DOI)000399388500004 ()
Note

QC 20170509

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2017-11-02Bibliographically approved
Hong, X., Ozolins, O., Guo, C., Pang, X., Zhang, J., Navarro, J. R., . . . Chen, J. (2017). 1.55-jnm EML-based DMT transmission with nonlinearity-aware time domain super-nyquist image induced aliasing. In: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings: . Paper presented at 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017, 19 March 2017 through 23 March 2017. Institute of Electrical and Electronics Engineers Inc..
Open this publication in new window or tab >>1.55-jnm EML-based DMT transmission with nonlinearity-aware time domain super-nyquist image induced aliasing
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2017 (English)In: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2017Conference paper (Refereed)
Abstract [en]

We experimentally demonstrate a DMT transmission system with 1.55-μm EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by ∼16.8%(33.1%) with proposed method for 4(40) km transmission.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2017
Keyword
Optical fibers, Aliasing, Linear equalization, Nyquist, Time domain, Transmission systems, Optical fiber communication
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-216490 (URN)2-s2.0-85025827916 (Scopus ID)9781943580231 (ISBN)
Conference
2017 Optical Fiber Communications Conference and Exhibition, OFC 2017, 19 March 2017 through 23 March 2017
Note

Funding details: CSC, China Scholarship Council; Funding details: 61307090, NSFC, National Natural Science Foundation of China; Funding details: 61550110240, NSFC, National Natural Science Foundation of China; Funding details: 61605047, NSFC, National Natural Science Foundation of China; Funding details: 61671212, NSFC, National Natural Science Foundation of China; Funding text: This work is supported by EIT Digital Royal Garden project, Swedish Research Council, Swedish Foundation for Strategic Research, Göran Gustafsson Stiftelse, China Scholarship Council, and National Natural Science Foundation of China (# 61550110240, 61671212, 61605047, 61307090). The equipment was funded by Knut and Alice Wallenberg foundation.

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2017-12-01Bibliographically approved
Hong, X., Ozolins, O., Guo, C., Pang, X., Zhang, J., Navarro, J. R., . . . Chen, J. (2017). 1.55-mu m EML-based DMT Transmission with Nonlinearity-Aware Time Domain Super-Nyquist Image Induced Aliasing. In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC): . Paper presented at Optical Fiber Communications Conference and Exhibition (OFC), MAR 19-23, 2017, Los Angeles, CA. IEEE.
Open this publication in new window or tab >>1.55-mu m EML-based DMT Transmission with Nonlinearity-Aware Time Domain Super-Nyquist Image Induced Aliasing
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2017 (English)In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC), IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

We experimentally demonstrate a DMT transmission system with 1.55-mu m EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by similar to 16.8%(33.1%) with proposed method for 4(40) km transmission.

Place, publisher, year, edition, pages
IEEE, 2017
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-210951 (URN)000403405800245 ()978-1-943580-23-1 (ISBN)
Conference
Optical Fiber Communications Conference and Exhibition (OFC), MAR 19-23, 2017, Los Angeles, CA
Note

QC 20170713

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2017-07-13Bibliographically approved
Matsui, Y., Schatz, R., Pham, T., Ling, W. A., Carey, G., Daghighian, H. M., . . . Roxlo, C. (2017). 55 GHz Bandwidth Distributed Reflector Laser. Paper presented at Optical Fiber Communications Conference and Exhibition (OFC), MAR 20-24, 2016, Anaheim, CA. Journal of Lightwave Technology, 35(3), 397-403.
Open this publication in new window or tab >>55 GHz Bandwidth Distributed Reflector Laser
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2017 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, no 3, p. 397-403Article in journal (Refereed) Published
Abstract [en]

We have demonstrated a 1300-nm short-cavity distributed reflector (DR) laser having 55 GHz bandwidth (BW), and successful 112-Gb/s transmission using four-level pulse-amplitude-modulation (PAM-4), without any pre-equalization for the transmitter. Two effects were realized in the design and operation of the DR laser: photon-photon (P-P) resonance and detuned-loading. The P-P resonance effect was realized between the DFB and distributed Bragg reflector (DBR) modes that coexisted in the cavity of the DR laser. The detuned-loading effect was used to effectively enhance the differential gain through the dynamic change in the mirror reflectivity that occurs on the flank of the DBR mirror due to the frequency chirp under modulation. Despite a limited RC cutoff frequency of 22 GHz, a wide modulation BW of 55 GHz was achieved. It is shown that the RC limitation was counteracted by the combined effects of the detuned-loading, which reduces the damping of relaxation oscillations, and an in-cavity FM-AM conversion effect that created a high-pass filter effect in the modulation response. This will be discussed by way of simulations and experimentally observed eye diagrams for 10 Gb/s NRZ and 28 Gbd PAM-4. The short-cavity DR laser achieved 112-Gb/s PAM-4 transmission over links having a range of dispersions from -28 to +7 ps/nm without precompensation on the transmitter.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
Keyword
100 Gbit/s Ethernet, direct modulation, distributed reflector lasers, PAM-4, pulse amplitude modulation, TOSA, transmitters
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-205525 (URN)10.1109/JLT.2017.2650678 (DOI)000397724700003 ()2-s2.0-85015848227 (Scopus ID)
Conference
Optical Fiber Communications Conference and Exhibition (OFC), MAR 20-24, 2016, Anaheim, CA
Note

QC 20170509

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2017-06-29Bibliographically approved
Udalcovs, A., Schatz, R., Wosinska, L. & Monti, P. (2017). Analysis of Spectral and Energy Efficiency Tradeoff in Single-Line Rate WDM Links. Journal of Lightwave Technology, 35(10), 1847-1857.
Open this publication in new window or tab >>Analysis of Spectral and Energy Efficiency Tradeoff in Single-Line Rate WDM Links
2017 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, no 10, p. 1847-1857Article in journal (Refereed) Published
Abstract [en]

This paper investigates, through simulations, the tradeoff between energy efficiency (EE) and the overall spectral efficiency (SE) of fiber optic links for a given capacity and a link length. The comparison is made for various modulation formats, span lengths, and with/without using forward error correction (FEC). The power consumption of the different system components is estimated from the data sheets of the state-of-the-art equipment. Results show that the use of long single-mode fiber spans (i.e., more than 40 km) improves EE when coherent modulation formats are used. However, with noncoherent formats, the span length must be selected depending on SE, aggregated traffic amount needs to be transmitted, and link length. For almost all modulation formats, FEC reduces the overall energy consumption despite being one of the main power consumers in fiber optic communication systems. The power consumption of 3Rs becomes particularly important when the linear crosstalk limits the system reach. In all other cases, the power consumption of transponders and optical line amplifiers is dominating, but their contribution changes depending on the aggregated traffic amount and system reach.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
Keyword
3R regeneration, energy efficiency, energy per bit, forward-error correction, modulation formats, span length, spectral efficiency
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-207655 (URN)10.1109/JLT.2017.2651165 (DOI)000399986700011 ()2-s2.0-85018908373 (Scopus ID)
Note

QC 20170607

Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-11-10Bibliographically approved
Rodrigo Navarro, J., Kakkar, A., Schatz, R., Pang, X., Ozolins, O., Udalcovs, A., . . . Jacobsen, G. (2017). Blind  phase  search  with  angular  quantization  noise mitigation for efficient carrier phase recovery. Photonics, 4(2), Article ID 37.
Open this publication in new window or tab >>Blind  phase  search  with  angular  quantization  noise mitigation for efficient carrier phase recovery
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2017 (English)In: Photonics, ISSN 2304-6732, Vol. 4, no 2, article id 37Article in journal (Refereed) Published
Abstract [en]

The inherent discrete phase search nature of the conventional blind phase search (C-BPS) algorithm is found to introduce angular quantization noise in its phase noise estimator. The angular quantization noise found in the C-BPS is shown to limit its achievable performance and its potential low complexity implementation. A novel filtered BPS algorithm (F-BPS) is proposed and demonstrated to mitigate this quantization noise by performing a low pass filter operation on the C-BPS phase noise estimator. The improved performance of the proposed F-BPS algorithm makes it possible to significantly reduce the number of necessary test phases to achieve the C-BPS performance, thereby allowing for a drastic reduction of its practical implementation complexity. The proposed F-BPS scheme performance is evaluated on a 28-Gbaud 16QAM and 64QAM both in simulations and experimentally. Results confirm a substantial improvement of the performance along with a significant reduction of its potential implementation complexity compared to that of the C-BPS.

Place, publisher, year, edition, pages
MDPI AG, 2017
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-207114 (URN)10.3390/photonics4020037 (DOI)2-s2.0-85029468731 (Scopus ID)
Note

QC 20170516

Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-11-08Bibliographically approved
Marinins, A., Ozolins, O., Pang, X., Udalcovs, A., Navarro, J. R., Kakkar, A., . . . Popov, S. (2017). Cylindrical Polymer Optical Waveguides with Polarization Independent Performance. In: CLEO: Science and Innovations. Paper presented at CLEO - Conference on Lasers and Electro-Optics. OSA Publishing.
Open this publication in new window or tab >>Cylindrical Polymer Optical Waveguides with Polarization Independent Performance
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2017 (English)In: CLEO: Science and Innovations, OSA Publishing , 2017Conference paper, Published paper (Refereed)
Abstract [en]

Heating of poly(methyl methacrylate) ridge optical waveguides slightly above glass transition temperature minimizes surface roughness and provides cylindrical shape. We experimentally demonstrate propagation loss decrease and polarization insensitivity as a result of waveguide thermal treatment.

Place, publisher, year, edition, pages
OSA Publishing, 2017
National Category
Atom and Molecular Physics and Optics Communication Systems
Identifiers
urn:nbn:se:kth:diva-215617 (URN)10.1364/CLEO_SI.2017.SF1J.6 (DOI)2-s2.0-85020313986 (Scopus ID)
Conference
CLEO - Conference on Lasers and Electro-Optics
Note

QC 20171106

Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-06Bibliographically approved
Zhang, L., Pang, X., Ozolins, O., Udalcovs, A., Schatz, R., Westergren, U., . . . Chen, J. (2017). Digital mobile fronthaul employing differential pulse code modulation with suppressed quantization noise. Optics Express, 25(25), 31921-31936.
Open this publication in new window or tab >>Digital mobile fronthaul employing differential pulse code modulation with suppressed quantization noise
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2017 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 25, p. 31921-31936Article in journal (Refereed) Published
Abstract [en]

A differential pulse code modulation (DPCM) based digital mobile fronthaul architecture is proposed and experimentally demonstrated. By using a linear predictor in the DPCM encoding process, the quantization noise can be effectively suppressed and a prediction gain of 7 similar to 8 dB can be obtained. Experimental validation is carried out with a 20 km 15-Gbaud/lambda 4-level pulse amplitude modulation (PAM4) intensity modulation and direct detection system. The results verify the feasibility of supporting 163, 122, 98, 81 20-MHz 4, 16, 64, 256 QAM based antenna-carrier (AxC) containers with only 3, 4, 5, 6 quantization bits at a sampling rate of 30.72MSa/s in LTE-A environment. Further increasing the number of quantization bits to 8 and 9, 1024 quadrature amplitude modulation (1024 QAM) and 4096 QAM transmission can be realized with error vector magnitude (EVM) lower than 1% and 0.5%, respectively. The supported number of AxCs in the proposed DPCM-based fronthaul is increased and the EVM is greatly reduced compared to the common public radio interface (CPRI) based fronthaul that uses pulse code modulation. Besides, the DPCM-based fronthaul is also experimentally demonstrated to support universal filtered multicarrier signal that is one candidate waveform for the 5th generation mobile systems.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-220601 (URN)10.1364/OE.25.031921 (DOI)000417591100100 ()29245861 (PubMedID)2-s2.0-85038213036 (Scopus ID)
Note

QC 20180116

Available from: 2018-01-16 Created: 2018-01-16 Last updated: 2018-01-16Bibliographically approved
Pang, X., Ozolins, O., El-Taher, A., Schatz, R., Jacobsen, G., Sergeyev, S. & Popov, S. (2017). Experimental Evaluation of Impairments in Unrepeatered DP-16QAM Link with Distributed Raman Amplification. PHOTONICS, 4(1), Article ID 16.
Open this publication in new window or tab >>Experimental Evaluation of Impairments in Unrepeatered DP-16QAM Link with Distributed Raman Amplification
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2017 (English)In: PHOTONICS, ISSN 2304-6732, Vol. 4, no 1, article id 16Article in journal (Refereed) Published
Abstract [en]

The transmission impairments of a Raman amplified link using dual-polarization 16-quadrature amplitude modulation (DP-16QAM) are experimentally characterized. The impact of amplitude and phase noise on the signal due to relative intensity noise (RIN) transfer from the pump are compared for two pumping configurations: first-order backward pumping and bi-directional pumping. Experimental results indicate that with increased Raman backward pump power, though the optical signal-to-noise ratio (OSNR) is increased, so is the pump-induced amplitude and phase noise. The transmission performance is firstly improved by the enhanced OSNR at a low pump power until an optimum point is reached, and then the impairments due to pump-induced noise start to dominate. However, the introduction of a low pump power in the forward direction can further improve the system's performance.

Place, publisher, year, edition, pages
MDPI AG, 2017
Keyword
Raman amplification, coherent communications, fiber optics communications
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-205475 (URN)10.3390/photonics4010016 (DOI)000398696700015 ()2-s2.0-85030865029 (Scopus ID)
Note

QC 20170524

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2017-11-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-3056-4678

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