10 research outputs found
Real-time Digital Signal Processing for Software-defined Optical Transmitters and Receivers
A software-defined optical Tx is designed and demonstrated generating signals with various formats and pulse-shapes in real-time. Special pulse-shapes such as OFDM or Nyquist signaling were utilized resulting in a highly efficient usage of the available fiber channel bandwidth. This was achieved by parallel data processing with high-end FPGAs. Furthermore, highly efficient Rx algorithms for carrier and timing recovery as well as for polarization demultiplexing were developed and investigated
Single-laser 32.5 Tbit/s Nyquist WDM transmission
We demonstrate 32.5 Tbit/s 16QAM Nyquist WDM transmission over a total length
of 227 km of SMF-28 without optical dispersion compensation. A number of 325
optical carriers are derived from a single laser and encoded with
dual-polarization 16QAM data using sinc-shaped Nyquist pulses. As we use no
guard bands, the carriers have a spacing of 12.5 GHz equal to the Nyquist
bandwidth of the data. We achieve a high net spectral efficiency of 6.4
bit/s/Hz using a software-defined transmitter which generates the electrical
modulator drive signals in real-time.Comment: (c) 2012 Optical Society of America. One print or electronic copy may
be made for personal use only. Systematic reproduction and distribution,
duplication of any material in this paper for a fee or for commercial
purposes, or modifications of the content of this paper are prohibite
Coherent terabit communications with microresonator Kerr frequency combs
Optical frequency combs enable coherent data transmission on hundreds of
wavelength channels and have the potential to revolutionize terabit
communications. Generation of Kerr combs in nonlinear integrated microcavities
represents a particularly promising option enabling line spacings of tens of
GHz, compliant with wavelength-division multiplexing (WDM) grids. However, Kerr
combs may exhibit strong phase noise and multiplet spectral lines, and this has
made high-speed data transmission impossible up to now. Recent work has shown
that systematic adjustment of pump conditions enables low phase-noise Kerr
combs with singlet spectral lines. Here we demonstrate that Kerr combs are
suited for coherent data transmission with advanced modulation formats that
pose stringent requirements on the spectral purity of the optical source. In a
first experiment, we encode a data stream of 392 Gbit/s on subsequent lines of
a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature
amplitude modulation (16QAM). A second experiment shows feedback-stabilization
of a Kerr comb and transmission of a 1.44 Tbit/s data stream over a distance of
up to 300 km. The results demonstrate that Kerr combs can meet the highly
demanding requirements of multi-terabit/s coherent communications and thus
offer a solution towards chip-scale terabit/s transceivers
Real-time Digital Signal Processing for Software-defined Optical Transmitters and Receivers
A software-defined optical Tx is designed and demonstrated generating signals with various formats and pulse-shapes in real-time. Special pulse-shapes such as OFDM or Nyquist signaling were utilized resulting in a highly efficient usage of the available fiber channel bandwidth. This was achieved by parallel data processing with high-end FPGAs. Furthermore, highly efficient Rx algorithms for carrier and timing recovery as well as for polarization demultiplexing were developed and investigated
Flexible WDM-PON with Nyquist-FDM and 31.25 Gbit/s per wavelength channel using colorless, low-speed ONUs
A remotely seeded flexible WDM network solution with 31.25 Gbit/s based on Nyquist sinc-pulses is demonstrated. The low-speed, colorless ONUs use remote heterodyne detection with electrical up- and down-conversion and SOAs for potential cost reduction.Peer ReviewedPostprint (published version
Flexible WDM-PON with Nyquist-FDM and 31.25 Gbit/s per wavelength channel using colorless, low-speed ONUs
A remotely seeded flexible WDM network solution with 31.25 Gbit/s based on Nyquist sinc-pulses is demonstrated. The low-speed, colorless ONUs use remote heterodyne detection with electrical up- and down-conversion and SOAs for potential cost reduction.Peer Reviewe
Colorless FDMA-PON with flexible bandwidth allocation and colorless, low-speed ONUs [invited]
We demonstrate a remotely seeded flexible passive optical network (PON) with multiple low-speed subscribers but only a single optical line terminal transceiver operating at a data rate of 31.25 Gbits/s. The scheme is based on a colorless frequency division multiplexing (FDM)-PON with centralized wavelength control. Multiplexing and demultiplexing in the optical network unit (ONU) is performed in the electronic domain and relies either on FDM with Nyquist sinc-pulse shaping or on orthogonal frequency division multiplexing (OFDM). This way the ONU can perform processing at low speed in the baseband. Further, the ONU is colorless by means of a remote seed for upstream transmission and a remote local oscillator for heterodyne reception, all of which helps in keeping maintenance and costs for an ONU potentially low and will simplify wavelength allocation in a future software defined network architecture. To extend the reach, semiconductor optical amplifiers are used for optical amplification in the downstream and upstream.Peer Reviewe