Chromatic Dispersion Fluctuations Research Articles

Design and Characterization of Dispersion-Tailored Silicon Strip Waveguides toward Wideband Wavelength Conversion

One of cost-effective ways to increase the transmission capacity of current standard wavelength division multiplexing (WDM) transmission systems is to use a wavelength band other than the C-band to transmit in multi-band. We proposed the concept of multi-band system using wavelength conversion, which can simultaneously process signals over a wide wavelength range. All-optical wavelength conversion could be used to convert C-band WDM signals into other bands in a highly nonlinear fiber (HNLF) by four-wave mixing and allow to simultaneously transmit multiple WDM signals including other than the C-band, with only C-band transceivers. Wavelength conversion has been reported for various nonlinear waveguide materials other than HNLF. In such nonlinear materials, we noticed the possibility of wideband transmission by dispersion-tailored silicon-on-insulator (SOI) waveguides. Based on the CMOS process has high accuracy, it is expected that the chromatic dispersion fluctuation could be reduced in mass production. As a first step in the investigation of the broadness of wavelength conversion using SOI-based waveguides, we designed and fabricated dispersion-tailored 12 strip waveguides provided with an edge coupler at both ends. Each of the 12 waveguides having different widths and lengths and is connected to fibers via lensed fibers or by lenses. In order to characterize each waveguide, the pump-probe experimental setup was constructed using a tunable light source as pump and an unmodulated 96-ch C-band WDM test signal. Using this setup, we evaluate insertion loss, input power dependence, conversion bandwidth and conversion efficiency. We confirmed C-band test signal was converted to the S-band and the L-band using the same silicon waveguide with 3 dB conversion bandwidth over 100-nm. Furthermore, an increased design tolerance of at least 90 nm was confirmed for C-to-S conversion by shortening the waveguide length. It is confirmed that the wavelength converters using the nonlinear waveguide has sufficiently wide conversion bandwidth to enhance the multi-band WDM transmission system.

Suppressing chromatic dispersion fluctuation for broadband optical parametric gain in highly nonlinear tellurite microstructured optical fibers

We investigate the effect of chromatic dispersion fluctuation on the performance of fiber optical parametric amplification (FOPA) using tellurite hybrid microstructured optical fibers which have highly nonlinear coefficient and high freedom in tailoring chromatic dispersion. When a tellurite-glass buffer layer is added around the central core, the new tellurite hybrid microstructured optical fiber can suppress the fluctuation of chromatic dispersion which is caused by the variation in the core diameter and fiber transverse geometry. As a result, high signal gain and broad bandwidth of FOPA can be maintained.

Design and experimental demonstration of a Fourier-domain mode-locked laser based on erbium-doped fiber amplifier

We describe a systematic approach to design, optimize, and characterize a Fourier-domain mode-locked (FDML) laser with an erbium-doped fiber amplifier (EDFA) as the optical gain medium. A highly stable temporal intensity profile is obtained by minimizing chromatic dispersion and polarization fluctuations. The obtained bandwidth of 21 nm, tuning speed of 50 kHz, and output power of 5 mW are the highest reported so far with an EDFA-based FDML laser.

Practical design rules for single-channel ultra high-speed dense dispersion management telecommunication systems

In this work, we establish some efficient and practical design rules for the implementation of single-channel ultra-high speed (>160-Gbit/s) telecommunication systems based on dense dispersion management. Moreover, we analyze some of actual implementation issues such as slope compensation scenario, junction losses, polarization mode dispersion and chromatic dispersion fluctuations.

Chromatic dispersion fluctuations in optical fibers due to temperature and its effects in high-speed optical communication systems

Several research groups have been proposing different dispersion compensation schemes, for very high-speed (⩾40Gbit/s) long-haul systems operating in the C-band window (1530–1563nm) over standard single mode fibers, known as ITU-T G.652 fibers. The focus on these high chromatic dispersion fibers is due to the large amount of standard single mode fibers already installed in the field. Although several dispersion compensation techniques have proved to be successful, the long term stability of this kind of systems remains to be seen. In fact, when in the field, these high speed systems present a very unstable behavior, which is translated in large variations of the bit error rate. In order to stabilize the systems strong forward error correction codes have been used. In this work, we prove quantitatively that this inherent instability is mainly due to chromatic dispersion variations induced by temperature swings. Two models for the chromatic dispersion and chromatic dispersion slope variations with temperature are developed and validated using laboratory measurements previously published. After the effect of temperature change is analyzed in terms of eye opening penalty, it is shown that for systems operating at 40Gbit/s and above temperature effects have to be considered in system design.

Reduction of dispersion impairment of soliton systems through chirp control at amplifier location

Through the use of dispersive elements to control the pulse chirp, it is shown that solitons can average even large chromatic dispersion fluctuations without creating much continuum. It is shown through numerical simulations that 40 Gbit/s can be transmitted with 100 km amplifier spacings over 1600 km without sorting fibres.

Continuum generated by chromatic dispersion and power variations in periodically amplified soliton links

The continuum generated by soliton power variations and chromatic dispersion fluctuations along the line of a periodically amplified system is analytically studied and numerically verified. A new design of two-step dispersion profiling is derived that leads to a reduction factor of the continuum energy of more than 9.

Nonlinear Evolution of Amplitude and Phase Modulated Signals and Performance Evaluation of Single-channel Systems in Long Haul Optical Fiber Links

In this work we numerically study the signal evolution in long haul links in presence of nonlinear Kerr effect, chromatic dispersion and ASE of the optical amplifiers, and the performance of long-haul IM-DD and PSK coherent systems is also evaluated. Propagation in condition of low and high chromatic dispersion is analyzed taking into account also the chromatic dispersion fluctuations. In the first propagation regime the signal presents a large spectral broadening due to the nonlinear interaction between ASE and signal. Conditions for transmission of NRZ intensity and phase modulated signals are found, even though the IM-DD systems present better performance. In the second propagation regime the nonlinear Kerr effect can compensate the degradation induced by the chromatic dispersion both for amplitude and phase modulated signals in the anomalous dispersion region. Also in this regime the IM-DD systems present better performance than the PSK ones and soliton propagation, included in this regime, allows us to obtain the best conditions for signal transmission. A performance comparison among optical systems, considering the two propagation regimes, shows that the best performance is obtained by means of soliton IM-DD systems in the case of very long distances (> 6000 km) and by means of conventional IM-DD systems operating at the zero dispersion wavelength in the case of long distances (< 6000 km). The zero dispersion wavelength condition can be practically obtained considering links with a fluctuating GVD presenting an average value equal to zero.