Sensitive and Accurate Dispersion Map Extraction of HNLFs by Frequency Tuning of a Degenerate FWM

A sensitive and accurate method for dispersion map extraction along an arbitrarily profiled highly nonlinear fiber (HNLF) is proposed. High sensitivity is achieved by positioning the wavelength of a signal at the band edge of the modulation instability (MI) spectrum generated by an intense degenerate four wave mixing (FWM) pump. In doing so, the to-be-extracted dispersion fluctuations leave a more drastic effect on the FWM-generated power since they either inflate or deflate theMI spectrum. The accuracy of the method is increased by monitoring the distribution of power along the fiber. Once the power distribution is measured along the fiber, dispersion map of the HNLF is extracted using an appropriate inverse algorithm, which reconstructs the dispersion with a highlevel ofaccuracy.

Optical Nyquist-pulse generation with a power difference to the ideal sinc-shape sequence of < 1%

Sinc-shaped Nyquist-pulses possess a rectangular spectrum. Thus, a sinc-pulse transmission minimizes the carrier spacing down to the baud rate, and therefore, substantially increases the transmissible data rates. These perspectives have led to a strong research activity in the field of Nyquist pulse transmission. However, all methods of Nyquist pulse generation shown up to now are rather complex, costly and none leads to ideal sinc-shaped Nyquist pulses. Thus, it has not been clear yet if Nyquist-pulse transmission can be incorporated in optical networks in an energy and cost-effective way. Here we present a method for the generation of almost ideal sinc-shaped Nyquist pulses based on a flat and phase-locked frequency comb. The pulses can be generated with conventional modulators without any sophisticated electronics or other costly equipment. In our proof-of-concept experiment we generate sinc-shaped Nyquist-pulse sequences which show a power difference lower than 1% compared to an ideal sequence. Generated sinc pulses have a full width at half maximum (FWHM) duration of 9.8 ps, an out-of-band suppression of more than 27 dB, a signal-to-noise ratio of more than 40 dB and a jitter of 82 fs, equivalent to 0.82% of the FWHM. The pulse width and repetition rate can be changed simply by tuning the comb parameters

Generation of Nyquist sinc pulses using intensity modulators

Optical sinc-shaped Nyquist pulses are produced based on the generation of an ideal frequency comb using cascaded intensity modulators. Nyquist pulses with 9.8-ps temporal width, 82-fs jitter and more than 40 dB SNR are achieved

Towards highest spectral efficiency: Optical sinc-shaped Nyquist pulses generation from rectangular frequency comb

In this paper, we review a method to produce optical sinc-shaped Nyquist pulses with unprecedented quality. The method is based on the synthesis of a rectangular shaped and phase-locked frequency comb from a combination of intensity modulators. The result is a highly flexible pulse generator that can easily be integrated in already installed communication systems. All-optical pulse shaping methods for highest spectral efficiencies are attractive since high-bitrate spectrally efficient channels can be combined into multiple Tbit/s superchannels, enabling ultrahigh data transmission rates and a simultaneous ultrahigh spectral efficiency. Ideal sinc-shaped Nyquist pulses thus unlock the path towards minimal inter-symbol interference and no-guard band wavelength multiplexing. Here we will report on the generation, modulation and multiplexing of the sinc-shaped pulses obtained while using off-the-shelf components

Optical sinc-shaped Nyquist pulses with very low roll-off generated from a rectangular frequency comb

High-quality optical sinc-shaped Nyquist pulses with a virtual zero roll-off factor are obtained from the generation of a phase-locked, rectangular-spectrum frequency comb. Tunability over more than 4 frequency decades is demonstrated with <1% power distortion

Highly tunable method to generate sinc-shaped Nyquist pulses from a rectangular frequency comb

A method to produce highly-stable optical sinc-shaped pulses is proposed based on the generation of a rectangular-spectrum frequency comb. Nyquist pulses with <1% power distortion, 82-fs jitter and more than 40 dB SNR are achieved