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Highest OSNR due to 18 photons/bit receiver sensitivity (excluding possible FEC gains), better than DQPSK, DPSK and any other schemeQuadrature phase shift keying: 2 bits / symbolWith added polarization division multiplex: 4 bits / symbol. Multiplies total fiber capacity by ~4 with respect to state-of-the art systems.Low symbol rate increases chromatic dispersion and PMD tolerances by factors of ~8 and 3, respectively, over those of standard intensity modulated systems.Evolutionary retrofitting of 40 Gbit/s transponders into existing 10 Gbit/s WDM systems
RZ symbol format makes the system nonlinearity-tolerant (XPM).Coherent optical receiver relaxes optical filtering requirementsElectrical received signals are proportional to optical fields
„Optical signal processing in the electrical domain“ becomes possible.Chromatic dispersion and polarization mode dispersion can be equalized electronically without any losses.
Early single-polarization QPSK demonstrations used external cavity lasers, which can not be used in real systems. External cavity lasers are MUCH TOO EXPENSIVE.First (and only) report of synchronous PSK with (standard) DFB lasers:
ECOC 1992
synQPSK: Baseband (I&Q) processing, QPSK, polarization division multiplexConcept allows to use off-the-shelf DFB lasers (1...2 MHz linewidth).
WP2: 90° hybrid and front end packaging (CeLight Israel)
Superposition of received and local oscillator optical fields with 0° and 90° phase shiftsI&Q baseband processingCo-packaging with IPAG‘s InP balanced photoreceivers
Univ. Paderborn, Germany: Optical Communication and High-Frequency Engineering
Founded 1992, headed by Reinhold Noé →Presently 13 group membersRecent achievements
PMD compensation at 10 and 40 Gbit/sLow-cost online chromatic dispersion measurement at 40 Gbit/s by arrival time detection with a sensitivity of 100 attoseconds
The productThe productPhotline family of components are designed to enable systems and modules manufacturers to meet the new challenges of the telecom market at 10 & 40 Gbit/s
Created end of 2000, Photline has brought to production a family of LiNbO3 modulators in less than 18 months.
Photline works in an environment of clean rooms for technological development, and is equipped with all the required laboratories for assembly and testing.
Design: simulation tools Epitaxy: 2 x MOVPE DFB grating, sub-micron HEMTs: electron beam lithographyFront-end: processing line for FP/DFB laser and PIN chipsBack-end: facet coating, dicing, 100% automated testingReliability: lifetime testing (Telcordia and MIL compliant)