Coded modulation for 100G coherent EPON

Geometrically shaped (GS) 8-, 16, and 32-ary modulation formats are investigated for use in coherent passive optical networks. The modulation formats are designed to improve receiver sensitivity when paired with a binary, soft-decision forward error correction code (SD-FEC), such as a low density parity check (LDPC). Herein we consider the LDPC code specified in the draft 50G EPON standard, and show how this type of code can be particularly advantageous in a coherent transmission system. A receiver sensitivity of −26.7 dBm is achieved at a post-FEC bit error rate below $3.8 \times 10^{-6}$ for a polarization-scrambled 32-ary GS modulation format at 25 GBd, received using a single-polarization, phasediverse coherent receiver. This yielded a bit rate of 100 Gbit/s, net of coding and pilot overhead. This modulation format was shown to perform equally well in transmission, with no observed dispersion penalty after 80 km standard single mode fiber. Finally, this modulation format was received, at a reduced data rate of 50 Gbit/s, using a heterodyne coherent receiver based on a single balanced photodiode. The receiver sensitivity for this simplified receiver configuration was −28.5 dBm, yielding a power budget of 34.2 dB

Coded modulation for 100G coherent EPON

Geometrically shaped (GS) 8-, 16, and 32-ary modulation formats are investigated for use in coherent passive optical networks. The modulation formats are designed to improve receiver sensitivity when paired with a binary, soft-decision forward error correction code (SD-FEC), such as a low density parity check (LDPC). Herein we consider the LDPC code specified in the draft 50G EPON standard, and show how this type of code can be particularly advantageous in a coherent transmission system. A receiver sensitivity of −26.7 dBm is achieved at a post-FEC bit error rate below $3.8 \times 10^{-6}$ for a polarization-scrambled 32-ary GS modulation format at 25 GBd, received using a single-polarization, phasediverse coherent receiver. This yielded a bit rate of 100 Gbit/s, net of coding and pilot overhead. This modulation format was shown to perform equally well in transmission, with no observed dispersion penalty after 80 km standard single mode fiber. Finally, this modulation format was received, at a reduced data rate of 50 Gbit/s, using a heterodyne coherent receiver based on a single balanced photodiode. The receiver sensitivity for this simplified receiver configuration was −28.5 dBm, yielding a power budget of 34.2 dB

Search of reference biomarkers reflecting orbital tissue remodeling in the course of Graves’ orbitopathy

Introduction. Graves’ orbitopathy (GO) is a complication in Graves’ disease (GD) that causes disfigurement and sometimes blindness. The pathogenesis of GO remains unknown, while its symptoms demonstrate dependence between the thyroid gland and the orbit. The ongoing inflammatory process in retrobulbar tissue results in its remodeling characterized by increased volume of the orbital contents involving adipose tissue, with fibrosis and adipogenesis as predominant features. This study was aimed at the immunohistochemical verification of potential contribution and correlation between orbital expressions of IGF-1R, CD34, Foxp-3, PPAR-γ and CD4, CD68, TGF-β, FGF-β in severe and mild (long-lasting) GO. Material and methods. Forty-one orbital tissue specimens — 22 patients with severe GO, 9 patients with mild GO and 10 patients undergoing blepharoplasty as a control group — were processed by routine immunohistochemistry. Results. Increased IGF-1R, CD34 and Foxp-3 expression was found in both severe and mild GO, yet a significant correlation between CD34 and CD4, CD68, TGF-β, FGF-β expressions was observed in long-lasting GO. Conclusions. CD34 expression is proposed to be the marker of orbital tissue remodeling in the course of mild GO