K. Worms

Simple all-optical FFT scheme enabling Tbit/s real-time signal processing

A practical scheme to perform the fast Fourier transform in the optical domain is introduced. Optical real-time FFT signal processing is performed at speeds far beyond the limits of electronic digital processing, and with negligible energy consumption. To illustrate the power of the method we demonstrate an optical 400 Gbit/s OFDM receiver. It performs an optical real-time FFT on the consolidated OFDM data stream, thereby demultiplexing the signal into lower bit rate subcarrier tributaries, which can then be processed electronically.

Free-space optical delay interferometer with tunable delay and phase.

A free-space optical delay interferometer (DI) featuring a continuously tunable time delay, polarization insensitive operation with high extinction ratios and accurate phase and time delay monitoring scheme is reported. The polarization dependence is actively mitigated by adjusting a birefringent liquid-crystal device. The DI has been tested for reception of D(m)PSK signals.

Tunable free space optical delay interferometer for demodulation of differential phase shift keying signals

With a continuously tunable free space optical delay interferometer and direct detection D(Q)PSK signals can be received at varying symbol rates or under optimized conditions. The interferometers phase is stabilized and its polarization dependence mitigated.

Novel optical fast fourier transform scheme enabling real-time OFDM processing at 392 Gbit/s and beyond

An optical FFT scheme is implemented and tested at 392 Gbit/s. It enables OFDM signal processing way beyond the bandwidth limits of electronics. The scheme operates with little energy as it exploits passive optical components.

Self-coherent receiver for PolMUX coherent signals

A compact polarization-diversity self-coherent receiver with reduced complexity is proposed. Requirements on input polarization tracking is relaxed by a variant CMA equalizer. Ex-periments are performed for 50 and 100 Gb/s PolMUX-NRZ-QPSK signals.

Terabit/s FFT processing – optics can do it on-the-fly

The discrete Fourier Transform (DFT) or its more popular efficient algorithm, the Fast Fourier Transform (FFT) is one of the important mathematical functions in the toolbox of signal processing. To this date its processing speed is limited by the underlying electronic processors. We show that FFT signal processing limitations can be overcome by performing the FFT in the optical domain and demonstrate the power of the technique by performing the FFT on a single source 10 Tbit/s OFDM signal.

Optical vector signal analyzer based on differential direct detection

A versatile optical vector signal analyzer is presented. The analyzer measures phase, intensity, eye diagrams and constellations without a local oscillator. Performance is demonstrated for 112 Gbit/s PolMUX DQPSK and other signal formats.