Silicon photonics technology is an enabler for the integration of complex circuits on a single chip, for various optical link applications such as routing, optical networks on chip, short range links and long haul transmitters. Quadrature Phase Shift Keying (QPSK) transmitters is one of the typical circuits that can be achieved using silicon photonics integrated circuits. The achievement of 25GBd QPSK transmitter modules requires several building blocks to be optimized: the pn junction used to build a BPSK (Binary Shift Phase Keying) modulator, the RF access and the optical interconnect at the package level. In this paper, we describe the various design steps of a BPSK module and the related tests that are needed at every stage of the fabrication process.
In this paper, we highlight the potential of Coherent PDM-QPSK format for next-generation 100Gb/s transmission
systems, through a record transmission experiment of 16.4Tb/s over 2550km, and in-depth experimental analyses of
tolerance to joint PMD and non-linear effects, as well as robustness to typical constraints of terrestrial optical networks.
While today's WDM optical networks are mostly based on 10Gbit/s data, modulated according to the non-return-to-zero
format and offer sub-Terabit/s capacities, networks at 40Gbit/s and beyond will likely use more complex modulation
formats, possibly involving more than 1 bit/symbol, for compatibility with the 50GHz channel spacing grid. For these
formats, two types of detection schemes can be considered: differential detection, or coherent detection. With differential
detection, we demonstrated 25.6Tb/s transmission over 240km, using 160 WDM channels on a 50GHz grid, each
containing two polarization-multiplexed 85.4Gb/s RZ-DQPSK signals. But coherent detection appears as an even more
promising technique for such multilevel formats, to reach higher transmission distances. It provides the real and
imaginary parts of the signal, at the expense of larger complexity and cost. These drawbacks should be weighted by the
promises offered by the technique when combined with advanced digital signal processing (DSP). DSP not only solves
some severe implementation issues, but also holds in store a tremendous potential against fiber impairments. In this
paper, we will focus on coherent detection solution and will demonstrate experimentally that a coherent receiver
involving DSP can mitigate distortions from chromatic dispersion, polarization-mode-dispersion and narrow optical
filtering, even after several thousand kilometers of fiber for 40 and 80Gb/s-modulated channels, thereby paving the way
for higher-capacity, longer-reach transparent optical networks, eventually taking advantage of efficient Polarization
In order to increase the channel bit rate of commercial submarine systems from 10Gb/s to 40Gb/s in a cost effective way, new technologies have to be implemented. We will review them including Raman amplification, modulation formats and PMD mitigation techniques. The introduction of Wavelength Division Multiplexing (WDM) has triggered a tremendous capacity growth in submarine systems, both by the increase of the number of WDM channels and by the increase of the channel bit-rate. Starting from 2.5Gbit/s in the mid-nineties, the bit-rate was upgraded to 10Gbit/s by the end of the century in commercial prudcts. The next generation of submarine systems will likely be based on 40Gbit/s bit rate. However, transmissions at 40Gbit/s rate are more challenging than transmission sat 10Gbit/s. The goal of this paper is to provide an overview of the technologies which could be required or used in next-generation submarine systems. In the first part of this paper, an overview of the history of submarine links is provided. Then the technologies used in current Nx10Gbit/s systems are described. Eventually, the challenges to overcome are discussed, whether they concern the type of fiber, the type of optical amplifier, or the nature of the modulation format.