ファイバ型FWMスイッチとラマン増幅器を用いた光波形変換

電気通信大学200

Performance of an Inline RZ-DPSK Pulse Compression Using Raman Amplifier and Its Application in OTDM Tributary

We experimentally investigate the performance of a distributed Raman amplifier (DRA)-based pulse compressor for a phase modulated signal. A 10 Gb/s return-to-zero (RZ)-differential phase shift keying (DPSK) signal is compressed to picosecond range after transmission. Pulsewidth is continuously compressed in a wide range from 20 to 3.2 ps by changing the pump power of the DRA while the compressed waveforms are well-matched with sech2 function. Error-free operations at bit-error-rate (BER) of 10-9 are achieved for the compressed signals of various pulsewidths with low power penalties within 2.3 dB compared to the back-to-back. After the compression, the 10 Gb/s signal is used to generate a 40 Gb/s RZ-DPSK optical time division multiplexing (OTDM) signal. This 40 Gb/s OTDM signal is then successfully demultiplexed to 10 Gb/s DPSK signal by using an optical gate based on four-wave mixing (FWM) in a highly nonlinear fiber (HNLF)

Waveform Conversion and Wavelength Multicasting with Pulsewidth Tunability Using Raman Amplification Multiwavelength Pulse Compressor

A combination of nonreturn-to-zero (NRZ)-to-return-to-zero (RZ) waveform conversion and wavelength multicasting with pulsewidth tunability is experimentally demonstrated. A NRZ data signal is injected into a highly nonlinear fiber (HNLF)-based four-wave mixing (FWM) switch with four RZ clocks compressed by a Raman amplification-based multiwavelength pulse compressor (RA-MPC). The NRZ signal is multicast and converted to RZ signals in a continuously wide pulsewidth tuning range between around 12.17 and 4.68 ps by changing the Raman pump power of the RA-MPC. Error-free operations of the converted RZ signals with different pulsewidths are achieved with negative power penalties compared with the back-to-back NRZ signal and the small variation among received powers of RZ output channels at a bit-error-rate (BER) of 10-9. The NRZ-to-RZ waveform conversion and wavelength multicasting without using the RA-MPC are also successfully implemented

Bioconvection gravitactique dans un milieu stratifié

International audienceNous considérons le phénomène de bioconvection gravitactique dans une cavité rectangulaire poreuse saturée d'un fluide stratifié. La bioconvection est due aux mouvements ascendants des micro-organismes qui sont légèrement plus denses que l'eau, tandis que la stratification du fluide est d'origine solutal et joue un rôle stabilisant. Il sera montré que la bioconvection stationnaire dans un milieu stratifié est un phénomène d'instabilité sous-critique qui est due d'une part au mouvement gravitactique des micro-organismes, et d'autre part à la faible diffusivité des solutés par rapport à celle des micro-organismes. Il sera aussi montré qu'il existe un régime de bioconvection oscillante qui peut s'établir en-dessous du seuil critique du régime de bioconvection stationnaire

STUDY ON THE PHOTOCATALYTIC DEGRADATION OF DICLOFENAC AND SULCOTRIONE IN SOME LAKE WATER SUBSTRATES IN HANOI

Joint Research on Environmental Science and Technology for the Eart

Impact of Frequency Shift on Nonlinear Compensation Using Optical Phase Conjugation for M-QAM Signals

Nonlinear compensation using optical phase conjugation (OPC) have been considered a promising technique to increase the reach of high-speed fiber-optic transmission systems. OPC-based nonlinear compensation employs an optical phase conjugation located at a middle of the fiber link to generate a complexed conjugated signal with respect the signal in the first half of the link for propagation in the second half. OPC technique assumes a symmetry for signal propagating in the first and second half to obtain a perfect nonlinear and chromatic dispersion. However, as most of practical OPC schemes are realized by nonlinear effects such as four-wave mixing or a combination of second-harmonic generation and difference frequency generation, the frequency shift induced by OPC affects the signal symmetrical requirement for nonlinear compensation because the chromatic dispersion is different for the first and second half transmissions. In this paper, we investigate the impact of frequency shift on the nonlinear compensation using OPC for high symbol rate, high level modulation format signals. This will be important to understand the tolerance of the OPC techniques against such a practical condition for actual system implementations

Simultaneous Compression of Multiple Pulse Streams for All-Optical Serial/Parallel Data Exchanges

We present our recent development of a simultaneous compression of multiple pulse streams utilizing the distributed Raman amplifier (DRA) for applications in serial/parallel high-speed data exchange. The optical clock pulse compression is operated based on adiabatic soliton compressor using DRA with pulsewidth tunable and multiple wavelength operations. We show an experimental demonstration of a simultaneous compression up to four 10 GHz clock pulse trains to picosecond pulsewidth range. The compressed multiple pulse streams are then used for applications in serial-to-parallel and parallel-to-serial data conversions which are one of key functionalities to realize all-optical wavelength/time-division trans-multiplexing in heterogeneous optical networks