1.6 Tbit/s (40/spl times/40 Gbit/s) DPSK transmission over 3/spl times/100 km of TeraLight fibre with direct detection

By transmitting 40 channels over 300 km of TeraLight fibre, it is shown that optical differential phase shift keying can be used in 100 GHz-spaced 40 Gbit/s systems, with direct detection and a simple receiving filter. Chromatic dispersion tolerance around 300 ps/nm is also measured, compared to 70 ps/nm for NRZ.     

3.2 Tbit/s (80 × 40 Gbit/s) phase-shaped binary transmissionover 3 × 100 km with 0.8 bit/s/Hz efficiency

50 GHz-spaced 80 × 40 Gbit/s WDM transmission over 300 km of TeraLight^TM fibre is demonstrated without polarisation demultiplexing, using the PSBT format. A record capacity of 3.2 Tbit/s is thus achieved over the C-band only, with a spectral efficiency of 0.8 bit/s/Hz     

Highly sensitive 565 Mb/s DPSK heterodyne transmission experiment using direct current modulation of a DFB laser transmitter

A comparison between external phase modulation and phase modulation obtained through direct current modulation of a multiquantum-well distributed feedback (DFB) transmitter is reported for a sensitive 565 Mb/s differential-phase-shift-keying (DPSK) heterodyne transmission experiment. A limited sensitivity penalty for direct phase modulation is expected from the driving current pulse shape, the transmitter FM response and the receiver characteristics. The experimentally observed 0.5 dB penalty is in agreement with theory and highlights the potential of direct DPSK modulation as compared to both standard DPSK and continuous-phase frequency shift keying (CPFSK) schemes.<>     

Nanocomposite materials based on chitosan and molybdenum disulfide

Molybdenum disulfide (MoS₂) was lithiated with n-butyllithium to obtain LiMoS₂. The exfoliation and re-stacking properties of LiMoS₂ allowed for the facile intercalation of chitosan into the re-stacked layers of MoS₂. A series of nanomaterials were synthesized, and characterized by powder-X-ray diffraction, thermogravimetric analysis, and four-probe electrical conductivity measurements. The chitosan–MoS₂ nanomaterial at 1:1 mol ratio displayed an increase in electrical conductivity value by a factor of 100 with respect to the pristine layered structure.     

How to launch 1 W into single-mode fiber from a single 1.48-μmflared resonator

The operation of 1.48-μm flared resonators is thoroughly studied, both experimentally and theoretically: the accurate determination of threshold condition as a function of geometrical and material parameters, the study of emission spectra and astigmatism variations as a function of optical power level allow us to better understand the may these devices operate. The origin of modal distortion is then analyzed, and an original solution is proposed to increase the single-transverse-mode power at high injection level: it is shown that implanting the multiple-quantum-well active layer with protons efficiently enhances the filtering capability of the overall structure, and particularly that of the ridge waveguide, by bringing additional lateral absorption losses. The explanation of the filtering mechanism is successfully confirmed by simulations using the beam-propagation method. This technique finally allowed more than 1.3 W of continuous wave (CW) diffraction-limited power at 6 A. Low-modal-gain structures were then realized to reduce modal optical absorption in the implanted structures with a view to maintaining a high external efficiency and a reduced vertical divergence. Finally, a three-lens coupling system was designed and the effects of optical feedback minimized so as to obtain a very high coupling efficiency: with an improved laser design, 1.12 W of CW power were then coupled into single-mode fiber at 6.6 A, which represents 65% of the power emitted by the laser chip     

WDM operation of a hybrid emitter integrating a wide-bandwidthon-chip mirror

A wide-bandwidth on-chip mirror based on a deeply etched Bragg grating localized over 10 μm is presented; it exhibits reflectivity over more than 25 nm. Integration within a laser-Mach-Zehnder modulator is shown and the wavelength-division multiplexing capability of the device demonstrated in a hybrid Bragg reflector configuration, by showing operation of the same InP chip with fiber gratings from 1534 to 1558 nm     

Nanomaterials Based on Polyanilines and MoSe2

Polyaniline, poly(N-methyl aniline), poly(2-ethyl aniline) and poly(2-propyl aniline) were intercalated into layered molybdenum diselenide by using the exfoliation/restacking property of Li_xMoSe₂. MoSe₂ was reacted with n-butyllithium to form Li_xMoSe₂. The Li_xMoSe₂ was exfoliated in N-methylformamide (NMF) with the help of ultrasonication which lead to the formation of single layers of MoSe₂. Addition of NMF solutions of the polymers to the exfoliated layers resulted in their intercalation into MoSe₂. The products were characterized by powder X-ray diffraction. Fourier transform infra-red spectroscopy, and four-probe van der Pauw technique electrical conductivity measurements are reported here for the first time.     

An intercalated polyaniline–titanate nanomaterial

In this paper we report on the synthesis of a nanomaterial consisting of polyaniline sandwiched between the sheets of layered titanate. This was achieved by first intercalating aniline into the titanate, followed by heat treatment in air. The resulting intercalate was characterized by powder X-ray diffraction, thermogravimetric analysis and FTIR spectroscopy.     

1.31-1.55-/spl mu/m phased-array demultiplexer on InP

The first demultiplexers on InP at 1.31-1.55 /spl mu/m based on low-order waveguide arrays have been fabricated and characterized. We show the calculated and measured spectral responses of two devices with 6 and 10 waveguides in the grating. The on-chip loss of the devices is 4.5 dB and the crosstalks are down to -25 dB. Thanks to their large bandwidth, the devices are polarization insensitive and no strong influence of the temperature is seen.     

Nanomaterials based on molybdenum diselenide

MoSe₂ has been encapsulated with a variety of guest species. This was achieved by first treating the MoSe₂ with an excess of n-BuLi to form the lithiated phase of MoSe₂ (Li_xMoSe₂). The Li_xMoSe₂ exfoliates readily in water or NMF to yield single layers of MoSe₂. Addition of solutions of polymers, organometallics, and even colloidal suspensions of layered materials to the single layers result in the formation of novel sandwiched compounds.