The explosive increase in data traffic over the last few decades has been driving the demand for high-capacity optical transmission systems. State-of-the-art spectrally efficient technologies such as high-order modulation formats, probabilistic constellation shaping (PCS) and high-performance forward error correction (FEC) have realized capacities very close to the theoretical limit of the wavelength bands used. The widely-used erbium-doped fiber amplifier (EDFA) is unable to support another wavelength-division multiplexing (WDM) channel because few amplification bands remain unused. Ultra-wideband (UWB) transmission with extra bandwidths, e.g., S, C and L bands, is a promising candidate for expanding transmission capacity. UWB systems can enlarge capacity without replacing any of the existing fiber infrastructure, which offers dramatic efficiencies in the cost and delay for system deployment. Recently, 100-Tb/s-class UWB transmission has been experimentally demonstrated, and the S-band region is regarded as the next candidate beyond conventional C and/or L band WDM systems. Designing such systems demands an understanding of how interchannel stimulated Raman scattering (ISRS) impacts WDM-system performance; because the S and L bands are separated by around 100 nm, ISRS is a significant issue.
In this paper, we investigate the effects of ISRS on signal quality of UWB transmission systems with experiments on S- (35 channel) and L- (40 channel) band WDM transmission using DP-16QAM signals. The results show that ISRS causes only signal power transfer, whereas the nonlinear cross-talk generated by ISRS has only minimal effect on signal quality. We prove the concept of UWB transmission by a DP-128QAM 150.3-Tb/s transmission experiment over a 40- km single-mode fiber in S, C, and L bands with WDM bandwidth of 13.6 THz; success is due to our proposed signal power optimization scheme which considers ISRS-induced power transfer between S and L bands.
Advanced modulation formats, e.g. multi-dimensional modulation, probabilistic shaping, and geometric shaping, are promising candidates to realize beyond 400 Gbps serial long haul transmission. Multi-dimensional modulation encoded with a short block length extends the minimum Euclidean distance between multi-dimensional symbols, resulting in improving noise tolerance. We have recently proposed eight-dimensional (8D)-16QAM with low-complexity iterative demodulation scheme and have demonstrated 600 Gbps/wavelength 120-GBaud 8D-16QAM WDM transmission over 3,900 km. In this paper, we discuss a design method of multi-dimensional modulation formats and demodulation techniques.
A joint field trial on 40G transmission was conducted, where Deutsche Telekom's and NTT's R&D groups got involved. 43-Gbit/s/ch CS-RZ signals of the NTT G.709-OTN system were transmitted over selected high-PMD fiber links in DT's actual field environment. The advantage of CS-RZ modulation format was confirmed in comparison with conventional NRZ against all-order (first- and higher-order) PMD. Moreover, we introduced a new scheme for an accelerated determination of outage probability due to PMD that is adapted to practical field conditions in an operated fiber network with buried fibers and in-line operational optical elements.
In high-speed and/or long-haul transmission systems with data rates of 40 Gbit/s and beyond, the system degradation due to 1st- and also higher-order polarization mode dispersion (PMD) is a significant issue. So far, PMD compensators have been proposed for 1st- and higher-order PMD.
In this paper, we focus on two types of optical PMD compensators, single-stage first-order compensator and double-stage compensator with higher-order canceller, and estimate their performances. Moreover, we propose a single-stage first & higher-order compensator as a “degenerate” version of the double-stage one by reducing the number of monitoring parameters (circuit) and the number of controllers (PCs). The functions of 1st- and higher-order PMD compensators are integrated into a single-stage configuration, with signal distortion monitoring at the output of the polarizer. The compensation performance of three PMD compensators is investigated in a 10.7 Gbit/s NRZ transmission system. The results show that the proposed single-stage compensator can effectively suppress the degradation due to 2nd-order PMD.
Relaxing the Optical Signal-to-Noise Ratio (OSNR) requirements of modern Wavelength Division Multiplexing (WDM) transmission systems/networks is essential due to the introduction of high-loss Optical Network Elements (ONE), the large channel numbers, and the very high channel-speeds. Forward Error Correction (FEC) codes are currently used in many applications, but the problem of the bit-rate increase caused by the redundancy will worsen as the channel-speed increases. This paper presents a novel error-controlling scheme that does not increase the bit-rate while offering OSNR relaxation. Error control is achieved by the two kinds of receiver proposed here, both of which are characterized by the diverse detection of dual-mode modulated signals, “consensus” logic for error detection, and multiple threshold selection for data recovery. After describing the “basic” receiver, an enhanced version is presented. Analyses based on the classical Gaussian noise approximation show the performances of these receivers. Experimental results show fair agreement with the analysis results, despite the simplifications used in the analyses. Experiments on the basic receiver show 3dB gain, and 9dB gain was observed with the addition of the standard RS(255,239) FEC code. 4dB gain is observed experimentally from the enhanced version of the receiver, and 10dB gain with the addition of RS(255,239).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.