Gain enhancement in multiple-pump-line Brillouin-based slow light systems by using fiber segments and filter stages.

We propose a delay line configuration to increase the time delay performance of multiple-pump-line Brillouin-based slow light systems. It consists of several short fibers interconnected by filters to block degrading spectral components. Three different delay line configurations are investigated experimentally with an optimized Brillouin spectrum composed of a superposition of a gain with two losses. An increase of the maximum time delay by 12% is reported, which is limited by the insufficient filter slew rates. We believe that the enhancement could be much higher by using filters with an improved slew rate performance.

Quasi-Light-Storage based on time-frequency coherence.

We show a method for distortion-free quasi storage of light which is based on the coherence between the spectrum and the time representation of pulse sequences. The whole system can be considered as a black box that stores the light until it will be extracted. In the experiment we delayed several 5 bit patterns with bit durations of 500ps up to 38ns. The delay can be tuned in fine and coarse range. The method works in the entire transparency range of optical fibers and only uses standard components of optical telecommunications. Hence, it can easily be integrated into existing systems.

Pulse broadening cancellation in cascaded slow-light delays.

This article describes a new approach to cancel the pulse broadening in a cascaded slow-light system. With the help of a simple experimental setup a method with significant potential to achieve a high pulse delay at almost zero pulse broadening is shown. Since the pulse reshaping is done inside a single delaying segment, this method can be used in connection with any other Brillouin based slow-light system.

Zero-broadening measurement in Brillouin based slow-light delays.

A novel method for the achievement of zero-broadening in a SBS based slow-light system is discussed in theory and demonstrated experimentally. The system is realized just with a single broadened Brillouin gain. It is shown, that if the gain bandwidth is much broader than the initial pulse width, the output pulse width decreases with increasing pump power. A compression of approximately 90 % of the initial pulse width was achieved in simulation and experiment.

Zero-broadening and pulse compression slow light in an optical fiber at high pulse delays.

We show in theory and experiment that in a SBS based delay line pulses can be delayed to more than a bit period without broadening. Zero-broadening is possible since the broadening due to the narrow Brillouin gain bandwidth can be compensated by the group velocity dispersion accompanied with the pulse delay. We achieve compensation by a superposition of a broad gain with two narrow losses at its wings. In our experiments 1.9ns pulses were delayed to around 1.5Bit, at the same time its FWHM width was compressed to 80%. Therefore, besides slowing down pulses, the method could have the potential to compensate the fiber dispersion.

Distortion reduction in Slow Light systems based on stimulated Brillouin scattering.

We show a simple method to reduce the distortions in SBS based slow light systems. The distortion reduction is simply based on a broadening and adaptation of the gain bandwidth. However, a broadened gain reduces the achievable fractional delay which cannot be compensated by higher pump powers. Here we will show that this compensation can be done by additional loss spectra. With the presented method low distortions for high fractional pulse delays are possible. We show the theory and experimental verifications of our method. For Gaussian pulses with a fractional delay of 1 Bit we achieved a distortion reduction of around 23%.

Comparison of delay enhancement mechanisms for SBS-based slow light systems.

We compare two simple mechanisms for the enhancement of the time delay in slow light systems. Both are based on the superposition of the Brillouin gain with additional loss. As we will show in theory and experiment if two losses are placed at the wings of a SBS gain, contrary to other methods, the loss power increases the time delay. This leads to higher delay times at lower optical powers and to an increase of the zero gain delay of more than 50%. With this method we achieved a time delay of more than 120ns for pulses with a temporal width of 30ns. To the best of our knowledge, this is the highest time delay in just one fiber spool. Beside the enhancement of the time delay the method could have the potential to decrease the pulse distortions for high bit rate signals.