| 301. |
- Li, Shen, 1994, et al.
(författare)
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Low-Complexity Voronoi Shaping for the Gaussian Channel
- 2022
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 70:2, s. 865-873
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Tidskriftsartikel (refereegranskat)abstract
- Voronoi constellations (VCs) are finite sets of vectors of a coding lattice enclosed by the translated Voronoi region of a shaping lattice, which is a sublattice of the coding lattice. In conventional VCs, the shaping lattice is a scaled-up version of the coding lattice. In this paper, we design low-complexity VCs with a cubic coding lattice of up to 32 dimensions, in which pseudo-Gray labeling is applied to minimize the bit error rate. The designed VCs have considerable shaping gains of up to 1.03 dB and finer choices of spectral efficiencies in practice compared with conventional VCs. A mutual information estimation method and a log-likelihood approximation method based on importance sampling for very large constellations are proposed and applied to the designed VCs. With error-control coding, the proposed VCs can have higher information rates than the conventional scaled VCs because of their inherently good pseudo-Gray labeling feature, with a lower decoding complexity.
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| 302. |
- Li, Shen, 1994, et al.
(författare)
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Power-Efficient Voronoi Constellations for Fiber-Optic Communication Systems
- 2023
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 41:5, s. 1298-1308
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Tidskriftsartikel (refereegranskat)abstract
- Voronoi constellations (VCs) are considered as an effective geometric shaping method due to their high power efficiencies and low complexity. In this paper, the performance of 16- and 32-dimensional VCs with a variety of spectral efficiencies transmitted in the nonlinear fiber channel are investigated. Both single-channel and wavelength-division multiplexing systems are considered for the transmission of the VCs, as well as different signal processing schemes, including chromatic dispersion compensation and digital backpropagation. Multiple performance metrics including the uncoded bit error rate, mutual information (MI), and generalized mutual information (GMI) of VCs are evaluated. Compared with quadrature amplitude modulation (QAM) formats, the VCs provide 1.0--2.4 dB launch power gains, up to 0.50 bits/symbol/dimension-pair MI gains, up to around 30% potential reach increase at the same MI, and up to 0.30 bits/symbol/dimension-pair GMI gains in a limited launch power range. The observed performance gains over QAM are found higher than in the back-to-back case. Moreover, a general GMI estimation method for very large constellations using importance sampling is proposed for the first time.
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| 303. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Demonstration of Degenerate Vector Phase-Sensitive Amplification
- 2013
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Ingår i: Optical Communication (ECOC 2013), 39th European Conference and Exhibition on. - : Institution of Engineering and Technology. - 9781849197595 ; 2013:622 CP, s. 492-494
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Konferensbidrag (refereegranskat)abstract
- The performance of a degenerate vector (dual cross-polarized pump) phase-sensitive amplifier (PSA) is characterized and compared to a degenerate scalar (dual co-polarized pump) PSA. In both schemes, we assess the gain as a function of the signal state of polarization, verifying its compliance with theory, and the phase transfer function.
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| 304. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Experimental analysis of degenerate vector phase-sensitive amplification
- 2014
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 22:18, s. 21889-21902
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Tidskriftsartikel (refereegranskat)abstract
- We comprehensively investigate a degenerate vector phase-sensitive amplifier (PSA). We determine the gain dependence on the relative phase and polarization angle between the pumps and the degenerate signal wave. The vector PSA is experimentally shown to be sensitive to the pump states of polarization (SOP) due to polarization mode dispersion in the fiber. However, the scheme performance agrees well with theory under specific pump SOPs and we achieve an on-off gain over 10 dB with a small deviation from the theoretically expected results. In comparison to the scalar scheme, the proposed vector scheme has larger tolerance for pump depletion due to four-wave mixing between pumps and generation of higher-order idlers.
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| 305. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Frequency-Comb Regeneration for Self-Homodyne Superchannels
- 2016
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 34:8, s. 1800-1806
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Tidskriftsartikel (refereegranskat)abstract
- We propose and demonstrate frequency-comb regeneration using injection locking and a parametric mixer. We theoretically evaluate the effect of the dispersive walk-off between the two unmodulated carriers from which the comb is regenerated. We calculate the maximum number of carriers which can be regenerated as a function of the laser linewidth and transmission distance when considering dispersion-unmanaged links. Experimentally, we demonstrate a 70 line comb generation without major linewidth degradation from two carriers with 15 dB optical signal-to-noise ratio (OSNR). The low OSNR operation is achieved by the use of optical injection locking. We also evaluate the degradation in the comb regeneration when the carriers are temporally decorrelated in order to emulate the effect of dispersive walk-off. When the temporal delay is 1.5 ns, the comb regeneration does not suffer from major degradation but when the delay is 10 ns, only 30 carriers can be regenerated without linewidth degradation, which agrees with our theoretical analysis.
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| 306. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Frequency-Comb Regeneration for Self-Homodyne Superchannels
- 2015
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Ingår i: 41st European Conference on Optical Communication, ECOC 2015, Valencia, Spain, 27 September - 1 October 2015. - 9788460817413 ; 2015-November, s. paper We.3.6.2-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate frequency-comb regeneration from two received unmodulated carriers usinga parametric mixer. For 10 dB optical signal-to-noise ratio of the unmodulated carriers, up to 60 carriersare generated without linewidth degradation.
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| 307. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Phase-Sensitive Amplification and Regeneration of Dual-Polarization BPSK without Polarization Diversity
- 2014
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Ingår i: 2014 European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Art. no. 6964045-
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Konferensbidrag (refereegranskat)abstract
- We analyze the performance of a degenerate vector PSA-based receiver and compare to an EDFA-based receiver, achieving an about 1 dB sensitivity improvement. We also assess the phase regeneration provided by the vector PSA when the signal phase is degraded.
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| 308. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Phase-Sensitive Amplification of 28 GBaud DP-QPSK Signal
- 2015
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Ingår i: 2015 Optical Fiber Communications Conference and Exhibition, OFC 2015, Los Angeles, United States, 22-26 March 2015. - Washington, D.C. : OSA. - 9781557529374 ; , s. 7122090-
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Konferensbidrag (refereegranskat)abstract
- We demonstrate, for the first time, amplification of a DP-QPSK signal using a vector phase-sensitive amplifier (PSA). The PSA-based receiver shows an about 0.7 dB sensitivity improvement compared to an EDFA-based receiver.
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| 309. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Polarization-Independent Phase-Sensitive Amplification
- 2016
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 34:13, s. 3171-3180
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Tidskriftsartikel (refereegranskat)abstract
- We thoroughly analyze the requirements on the signal and idler state of polarizations (SOPs) for achieving maximum amplification in phase-sensitive amplifiers (PSAs). These requirements are described using a Jones-space description as well as a Stokes-space description. Our analysis includes the cases of polarization-diverse and vector PSAs, and in each type of PSA, we also consider the signal-degenerate and the non-degenerate schemes. We observe that the relation between the signal and idler SOPs to achieve maximum phase-sensitive (PS) amplification can be described similarly in polarization-diverse and in vector PSAs. Moreover, both types of PSAs are polarization-dependent, which means that PSAs do require polarization-tracking schemes when being implemented in a realistic optical-transmission scenario. We therefore evaluate how polarization tracking of the signal and the idler SOPs can overcome the theoretical polarization dependence of both polarization-diverse and vector PSAs. We find that only one polarization tracker for either the signal or idler SOP is necessary for achieving polarization-independent PS amplification when considering the general case of dual-polarization (DP) modulated signals. This polarization tracker requires the control of three degrees of freedom which describe a general polarization rotation. For single-polarization (SP) modulated signals, the polarization tracker can rotate both the signal and the idler SOPs simultaneously which eliminates the need for splitting the signal and the idler before the PSA. Moreover, only two degrees of freedom for the polarization tracker are necessary in this case. When considering degenerate schemes, a polarization tracker with two degrees of freedom is sufficient to achieve maximum PS amplification of DP binary phase-shift keying (BPSK) signals in both vector and polarization diverse PSAs. For the case of SP-BPSK signals, a polarization-diverse PSA can perform polarization-independent amplification by controlling the relative phase between the pumps, whereas a polarization tracker with only one degree of freedom is necessary in the case of vector PSAs.
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| 310. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
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Quadrature decomposition of a 20 Gbaud 16-QAM signal into 2×4-PAM signals
- 2016
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Ingår i: 2016 European Conference in Optical Communication.
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Konferensbidrag (refereegranskat)abstract
- We propose a novel phase-sensitive processor capable of operating at low nonlinear phase shifts. With a nonlinear phase shift of 2 0.15 rad, quadrature decomposition is demonstrated with penalty of 0.5 dB at BER=10E-3.
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