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The development of 100 Gb/s transponder technology is progressing rapidly to meet the needs of next-generation optical/IP carrier networks. Video-driven IP traffic growth continues together with the need for ever higher-speed ports on IP routers, Ethernet switches, and OTN cross-connects, thus driving the requirements for cost-effective client and line side 100 Gb/s transponders. For a short time to market, 100 Gb/s transponders should be deployable using 10 Gb/s link-engineering rules over existing fiber and DWDM infrastructure. In this article we describe the upgrade of an installed 10 Gb/s field system to 100 Gb/s using a real-time single-carrier coherent 100G polarization multiplexed quadrature phase shift keyed (PM-QPSK) channel. Performance sufficient for error-free operation after forward error correction was achieved over installed 900 km and 1800 km links, proving the viability of 100 Gb/s upgrades to most installed systems. Excellent tolerance to fiber polarization mode dispersion and narrowband optical filtering demonstrates the applicability of this technology over the majority of installed fiber plant and through existing 50 GHz reconfigurable optical add/drop multiplexers. [ABSTRACT FROM AUTHOR]

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Abstract: Sustainable forest management (SFM), an explicit policy objective in Canada, balances social, economic and environmental values. The status and trends of forest-associated species is one indicator of SFM, though it is under utilized due to challenges with indicator selection and data availability. This paper demonstrates and tests an indicator selection methodology which combines Breeding Bird Survey (BBS) data and LandSat land cover data to identify indicator guilds, or groups of indicator species, for a series of forest composition and configuration attributes in the Great Lakes St. Lawrence forest region. Guild performance is tested at independent sites within the region and compared with that of guilds assembled using known species’ habitat preferences, and abundance trends are reported for two periods: 1990–2007 and 1967–2007. Guilds assembled using the method proposed here describe more variation in forest composition (r-sq(adj): 41–76) than those assembled using known habitat preferences alone (r-sq(adj): 17–58). Forest configuration guilds, which were not compared with existing guilds, also describe a large proportion of variation in configuration attributes (r-sq(adj): 47–76). Guild abundance remained stable over the long and short term for most guilds with the exception of the wetland guild, which increased moderately over the long-term, and the deciduous guild which increased moderately over the short-term. Despite challenges associated with the use of bird guilds as indicators of forest composition and configuration, results presented here suggest that indicator guilds may provide useful information regarding the status and trends of regional scale forest composition and configuration attributes. [Copyright &y& Elsevier]

In addition to linear compensation of fiber channel impairments, coherent receivers also provide colorless selection of any desired data channel within multitude of incident wavelengths, without the need of a channel selecting filter. In this paper, we investigate the design requirements for colorless reception using a coherent balanced receiver, considering both the optical front end (OFE) and the transimpedance amplifier (TIA). We develop analytical models to predict the system performance as a function of receiver design parameters and show good agreement against numerical simulations. At low input signal power, an optimum local oscillator (LO) power is shown to exist where the thermal noise is balanced with the residual LO-RIN beat noise. At high input signal power, we show the dominant noise effect is the residual self-beat noise from the out of band (OOB) channels, which scales not only with the number of OOB channels and the common mode rejection ratio (CMRR) of the OFE, but also depends on the link residual chromatic dispersion (CD) and the orientation of the polarization tributaries relative to the receiver. This residual self-beat noise from OOB channels sets the lower bound for the LO power. We also investigate the limitations imposed by overload in the TIA, showing analytically that the DC current scales only with the number of OOB channels, while the differential AC current scales only with the link residual CD, which induces high peak-to-average power ratio (PAPR). Both DC and AC currents at the input to the TIA set the upper bounds for the LO power. Considering both the OFE noise limit and the TIA overload limit, we show that the receiver operating range is notably narrowed for dispersion unmanaged links, as compared to dispersion managed links., (© 2012 Optical Society of America)

Advanced modulation schemes together with coherent detection and digital signal processing has enabled the next generation high-bandwidth optical communication systems. One of the key advantages of coherent detection is its superior receiver sensitivity compared to direct detection receivers due to the gain provided by the local oscillator (LO). In unamplified applications, such as metro and edge networks, the ultimate receiver sensitivity is dictated by the amount of shot noise, thermal noise, and the residual beating of the local oscillator with relative intensity noise (LO-RIN). We show that the best sensitivity is achieved when the thermal noise is balanced with the residual LO-RIN beat noise, which results in an optimum LO power. The impact of thermal noise from the transimpedance amplifier (TIA), the RIN from the LO, and the common mode rejection ratio (CMRR) from a balanced photodiode are individually analyzed via analytical models and compared to numerical simulations. The analytical model results match well with those of the numerical simulations, providing a simplified method to quantify the impact of receiver design tradeoffs. For a practical 100 Gb/s integrated coherent receiver with 7% FEC overhead, we show that an optimum receiver sensitivity of -33 dBm can be achieved at GFEC cliff of 8.55E-5 if the LO power is optimized at 11 dBm. We also discuss a potential method to monitor the imperfections of a balanced and integrated coherent receiver.