Kai-Uwe Lauterbach

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.

Theoretical and experimental investigation of Brillouin scattering for the generation of millimeter waves

We investigate and discuss stimulated Brillouin scattering in optical fibers for the generation of millimeter waves in theory and experiment. With a derivation of the responsible differential equation system we show that the phases of two independently amplified sidebands of a frequency comb will remain the same. Neither third-order nonlinear effects like self- and cross-phase modulation nor the Brillouin amplification has an influence on the phases. We verify our theoretical predictions with phase noise measurements of the generated millimeter-wave signal. The results show that the generated phase noise is in fact very low.

Potential ultra wide slow-light bandwidth enhancement.

We describe a method which has the potential to enhance the bandwidth of Brillouin based slow-light delay lines drastically. It is based on the overcompensation of the anti Stokes loss spectrum by additional pump sources. With this method it might be possible to overcome the bandwidth limit of Brillouin scattering which for one pump wave is given by two times the natural Brillouin shift in the incorporated waveguide. We will show experimentally that pulses can be delayed in the overcompensated loss spectrum.

Time delay enhancement in stimulated-Brillouin-scattering-based slow-light systems

We show a simple method of time delay enhancement in slow-light systems based on the effect of stimulated Brillouin scattering. The method is based on the reduction of the absolute Brillouin gain by a loss produced by an additional pump laser. With this method we achieved pulse delays of nearly 100 ns in a standard single-mode fiber. In the presented approach the delay or acceleration of optical signals is decoupled from their amplification or attenuation, which allows the adaptation of the pulse amplitudes to the given application.

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%.

High Quality Millimeter Wave Generation via Stimulated Brillouin Scattering

A new and simple method for the generation and modulation of Millimeter waves is presented. Based on frequency upconversion via Stimulated Brillouin Scattering, it is very flexible in its output frequency and modulation bandwidth.

High resolution spectroscopy on optical signals in fiber communication systems

In this paper, we present Brillouin based optical spectrum analysis with 10 ms sweep time and 23 MHz resolution bandwidth in the optical C-Band. The proposed measurement method has the potential to reduce the sweep time and the resolution bandwidth.

Fast and simple high resolution optical spectrum analyzer

A simple method for fast optical spectroscopy with high resolution is shown. The method is based on the narrowband Brillouin gain process in optical fibers.

Slow and Fast-Light in optical fibers ’ An overview

Slow- and fast-light is the control of the velocity of light in a medium by light. As a fascinating new field in physics there is a fundamental interest on this effect on the one side, but on the other side there exist a lot of practical applications for telecommunication and information systems. Among these are optical signal processing, the radio frequency-photonics, nonlinear optics and spectroscopy in time domain. Furthermore, the slow- and fast-light effect can be seen as a key technology for optical delay lines, buffers, equalizers and synchronizers in packed switched networks. To realize the effect there are different methods and material systems possible. Beside these especially the nonlinear effect of stimulated Brillouin scattering (SBS) is of special interest because it has several advantages. This article gives an overview about the fundamentals and limits of the slow-and fast-light effect in general and based on the SBS in optical fibers. Some experimental results which were achieved so far are shown.

Enhancement of maximum time delay in one fiber segment slow light systems based on stimulated Brillouin scattering

An effective method to enhance the time delay in SBS-based slow-light systems by decoupling the delay from the Brillouin gain is shown. A drastic improvement of the time delay in one fiber segment was achieved.