Remotely-pumped network-embedded self-tuning transmitter for 80-Gb/s conventional hybrid TDM/WDM PON with 256-split.

We present a colorless network-embedded self-tuning transmitter assisted by a remotely pumped erbium-doped double-pass amplifier located at the remote node for a conventional hybrid stacked-WDM/TDM-PON. The scheme provides up to 256-split PON with 80-Gb/s aggregate upstream capacity obtained with RSOA direct modulation at 2.5 Gb/s.

Efficient modulation cancellation using reflective SOAs.

Modulation cancellation and signal inversion are demonstrated within reflective semiconductor optical amplifiers. The effect is necessary to implement colorless optical network units for network end-users, where downstream signals need to be erased in order to reuse the carrier for upstream transmission. The results presented here indicate that reflective semiconductor optical amplifiers possess the perfect high-speed all-optical gain saturation characteristics to completely cancel the downstream modulation at microwatt optical power levels and are thus the prime candidate to be constituents of future optical network units. Theoretical considerations are supported by experiments that show the cancellation of signals with a 6 dB extinction ratio at 2.5 Gbit/s.

Network-embedded self-tuning cavity for WDM-PON transmitter.

A network-embedded self-tuning cavity is proved in wavelength division multiplexed passive optical network transmission over 32 channels. The external source-less topology takes advantage of a reflective element at the remote node and a reflective semiconductor optical amplifier at the optical network unit to establish a distribution-fiber based cavity. The bit error rate performance of up to 5-km cavities is presented with two optical network units simultaneously operating and with downstream signal co presence. The experimental analysis at 1.25 Gb/s provides an evaluation of polarization dependences when exploiting low polarization dependent gain reflective semiconductor optical amplifiers with 25-km and 50-km standard single mode fiber transmission.

Impact of time-interleaving on directly-detected 100-Gb/s POLMUX RZ-DQPSK robustness to PDL-induced crosstalk.

The impact of PDL-induced crosstalk on 100-Gb/s POLMUX RZ-DQPSK performance is investigated both experimentally and through numerical simulations in direct detection systems. We found that RZ time-interleaving, contrary to what happens with PMD, features a strong robustness to PDL. The detrimental effect of optical narrow filtering on PDL-induced penalty is also analyzed; RZ time-interleaving still proves the best solution to deal with the PDL issue.

All-optical wavelength conversion of a 100-Gb/s polarization-multiplexed signal.

We present the results of an in-depth experimental investigation about all-optical wavelength conversion of a 100-Gb/s polarization-multiplexed (POLMUX) signal. Each polarization channel is modulated at 25 Gbaud by differential quadrature phase-shift keying (DQPSK). The conversion is realized exploiting the high nonlinear chi((2)) coefficient of a periodically poled lithium niobate waveguide, in a polarization-independent configuration. We find that slight non-idealities in the polarization independent setup of the wavelength converter can significantly impair the performance of POLMUX systems. We show that high-quality wavelength conversion can be nevertheless achieved for both the polarization channels, provided that an accurate optimization of the setup is performed. This is the first demonstration, to the best of our knowledge, of the possibility to obtain penalty-free all-optical wavelength conversion in a 100-Gb/s POLMUX transmission system using direct-detection.

Coordinate change of c-myc, transferrin receptor and H3 gene expression precedes induction of haemoglobin-producing cells of the leukaemia K562 cell line treated with cis-diamminedichloroplatinum (II).

Erythroid cell differentiation can be achieved in vitro by means of several chemical or natural agents. Cell differentiation is accompanied by biochemical and molecular changes which show that the inducer is active at different molecular levels. Among the chemical agents that are able to induce cell differentiation, the anticancer drugs are of great interest for the emerging study of in vitro and in vivo models for differentiation treatment. Cis-diamminedichloroplatinum II (CDDP), a crosslinking DNA compound, is usually employed at a high dosage in treating solid tumors. We have demonstrated that CDDP was also able to induce K562 cells towards erythroid differentiation. In our experiment 2.5 micrograms/ml of CDDP caused expression of alpha-globin chain gene and production of haemoglobulin. Continuous presence of the drug was not necessary to induce the cell to produce haemoglobin. Five days after CDDP treatment, the expression of c-myc oncogene had risen, while H3 histone mRNA expression fell to undetectable levels within 24 hours. Transferrin (Tf) receptor mRNA was reduced but later (about 48 hours) than c-myc and H3 messenger RNAs. The inhibition of cell proliferation was correlated both with the reduced expression of Tf receptor mRNA and low expression of the protein. However, expression of the cytoskeleton vimentin gene was only slightly affected during the time-course of the experiment. Data show that at least three phases were present in the irreversible CDDP induction of haemoglobin synthesis in the K562 cell. The erythroid differentiation was first preceded by a rise of c-myc mRNA, which probably precommits the cell towards the erythroid lineage. The mRNA levels of the cell-cycle dependent genes, H3 and Tf receptor, decreased and inhibition of DNA synthesis and loss of cell proliferation were detected. Finally, the alpha-globin chain gene was actively transcribed and the cell produced haemoglobin.