Bengt-Erik Olsson

A simple and robust 40-Gb/s wavelength converter using fiber cross-phase modulation and optical filtering

40-Gb/s return-to-zero data wavelength conversion is demonstrated using cross-phase modulation in an optical fiber with subsequent conversion of phase modulation to amplitude modulation using an optical filter. The scheme is potentially ultrahigh speed and can be made polarization independent.

All-optical demultiplexing using fiber cross-phase modulation (XPM) and optical filtering

All-optical demultiplexing of 80-Gb/s data to 10 Gb/s is demonstrated using spectral broadening-induced by cross-phase modulation (XPM) with subsequent optical band-pass filtering. Due to the time derivative effect of XPM, the control pulsewidth can be larger than the bit-slot of the incoming data, and still give a switch window suitable for demultiplexing. Operation at 10/sup -12/ bit-error rate is demonstrated. In principle, this approach will scale to extremely high bit rates due to the ultrafast fiber nonlinearities.

WDM to OTDM multiplexing using an ultrafast all-optical wavelength converter

A robust and scalable all-optical multiplexer combining four 10-Gb/s WDM channels into one 40-Gb/s OTDM channel is presented. The multiplexer generates a coherent output data stream, which does not suffer from channel interference as passively generated OTDM data do.

Pulse restoration by filtering of self-phase modulation broadened optical spectrum

Restoration of distorted optical pulses is achieved using nonlinear fiber self-phase spectral broadening and subsequent optical band-pass filtering of a single sideband. Using this technique, the output pulsewidth is shown to remain constant for input pulse-widths between 9-20 ps. A detailed investigation of the signal-to-noise ratio shows that best performance is obtained by operating in normal fiber dispersion regime. This technique is also applied to restore 40 Gb/s RZ-data suffering distortion from polarization mode dispersion. The high-bandwidth fiber nonlinearity shows promise to scale to higher bit rate pulse distortion correction.

80 to 10 Gbit/s demultiplexing using fiber cross-phase modulation and optical filtering

We demonstrate a new demultiplexer based on XPM in a fiber that utilizes the derivative feature of XPM induced spectral broadening. The basic idea is that the leading edge of the control pulse generates a red shift of the spectrum of the XPM modulated input signal, and the trailing edge generates a blue shift. We have previously reported wavelength conversion using this technique where the incoming data phase modulate continuous wave (CW) light with subsequent conversion to amplitude modulation. Here, only one of the OTDM data channels in the high bit-rate data is spectrally broadened and that channel can then be extracted with a narrow band optical band-pass filter at either side of the original spectrum. Thus, only one edge of the control pulse governs the width of the demultiplexing switch window, if dispersive walk-off is neglected. Therefore a control pulse broader than the actual bit slot can be used for demultiplexing. Another important feature of this demultiplexer compared to the NOLM is that it is not an interferometer, which makes the device completely insensitive to environmental disturbances even though a long length of fiber is used.

A simple and robust high-speed wavelength converter using fiber cross-phase modulation and filtering

40 Gbit/s RZ data wavelength conversion is demonstrated using cross-phase modulation in an optical fiber with subsequent conversion of phase modulation to amplitude modulation using an optical filter. The scheme is potentially ultra high speed and can be made polarization independent.

Noise in sliced self-phase modulation broadened spectrum

Summary form only given.Recently there has been a great interest in applications where a slice of a broad optical spectrum generated by nonlinear effects in a fiber is filtered out by selecting a narrow part of the spectrum with an optical filter. When operating in anomalous dispersion regime in the fiber, the filtered pulses become noisy if the input pulses are not extremely stable in amplitude and the signal to noise ratio (SNR) is very high. This is due to unstable excitation of higher order solitons either due to amplitude fluctuations in the input pulse itself or due to beating between the pulse and optical noise, e.g., from an erbium-doped fiber amplifier (EDFA). This phenomenon has been shown to become a severe limitation in the generation of super continuum where the input peak power has to be extremely high compared to the generation of a fundamental soliton. In this communication we show that this effect also has severe noise implications even at the much lower input power required for moderate SPM broadening of the spectrum. Here, the growth of noise is characterized by measuring the SNR versus input power for a sliced SPM broadened spectrum. Random generation of higher order solitons, when pumping the fiber in the anomalous dispersion regime, may also impair other all optical fiber devices, like the nonlinear optical loop mirror and devices relying on four wave mixing.

Optical packet switching and associated optical signal processing

In this talk we will review functions for optical packet switching and ultra-fast network functions that can be handled using all-optical signal processing technologies. We will review research results utilizing ultra-fast all-optical nonlinear fiber wavelength converters and InP integrated optical wavelength converters. Application to all-optical label swapping and WDM/OTDM networks will be discussed.

Generation of 1O GHz pulse packets from an actively mode-locked fiber ring laser

A method to generate packets of short (10 ps) high quality pulses directly from an actively mode-locked fiber ring laser at 10 GHz is demonstrated by locking the packet repetition frequency to the fundamental laser cavity frequency.