Miguel Iglesias Olmedo

Multiband Carrierless Amplitude Phase Modulation for High Capacity Optical Data Links

Short range optical data links are experiencing bandwidth limitations making it very challenging to cope with the growing data transmission capacity demands. Parallel optics appears as a valid short-term solution. It is, however, not a viable solution in the long-term because of its complex optical packaging. Therefore, increasing effort is now put into the possibility of exploiting higher order modulation formats with increased spectral efficiency and reduced optical transceiver complexity. As these type of links are based on intensity modulation and direct detection, modulation formats relying on optical coherent detection can not be straight forwardly employed. As an alternative and more viable solution, this paper proposes the use of carrierless amplitude phase (CAP) in a novel multiband approach (MultiCAP) that achieves record spectral efficiency, increases tolerance towards dispersion and bandwidth limitations, and reduces the complexity of the transceiver. We report on numerical simulations and experimental demonstrations with capacity beyond 100 Gb/s transmission using a single externally modulated laser. In addition, an extensive comparison with conventional CAP is also provided. The reported experiment uses MultiCAP to achieve 102.4 Gb/s transmission, corresponding to a data payload of 95.2 Gb/s error free transmission by using a 7% forward error correction code. The signal is successfully recovered after 15 km of standard single mode fiber in a system limited by a 3 dB bandwidth of 14 GHz.

Towards 400GBASE 4-lane solution using direct detection of MultiCAP signal in 14 GHz bandwidth per lane

We report on an experimental demonstration of 102 Gbit/s transmission over a 15km single wavelength and polarization fiber link with 14GHz 3dB bandwidth. Novel multi-band CAP signaling allows for a 4-lane 400GBASE long reach solution.

O-band 400 Gbit/s Client Side Optical Transmission Link

We present an O-band 400 Gbit/s optical client side Ethernet link with 40 km SSMF reach employing four LAN-WDM lanes, MultiCAP modulation and direct detection.

Quaternary Polarization-Multiplexed Subsystem for High-Capacity IM/DD Optical Data Links

We demonstrate for the first time an intensity-modulated direct-detection link using four states of polarization. The four data-independent tributaries are each assigned distinct states of polarization to enable the receiver to separate the signals. Polarization rotation due to propagation over optical fiber is tracked and compensated with simple digital signal processing in Stokes space. Transmission below the forward error correction limit is shown for maximum net bitrates of 100 Gb/s (4 × 27 GBd) and 120 Gb/s (4 × 32 GBd) over 2-km standard single-mode fiber at a center wavelength of 1550 nm.

Carrier Phase Recovery Algorithms for Coherent Optical Circular mQAM Systems

The phase noise tolerance of circular multilevel quadrature amplitude modulation (C-mQAM) constellations employing different carrier phase recovery (CPR) algorithms is studied. A differential decoding scheme and a bit mapping for this type of constellations are proposed. A novel CPR scheme for C-mQAM constellations is also presented. The particular distribution of the constellation points in a C-mQAM signal is exploited to reduce the required Nth power for the removal of the modulation component by a factor of two. Hence, the computational complexity of the proposed algorithm is drastically reduced. The combined linewidth symbol duration product (ΔνTs) tolerance of different CPR algorithms for C-mQAM constellations is studied and compared with the proposed CPR scheme. The results are analyzed at 3.8e-3 and 1e-2 bit error rate forward error correction limits. The proposed CPR scheme achieves similar ΔνTs tolerance compared to single stage BPS algorithm while its computational complexity is reduced by group factors of 27.2 | 32.3, and 30.5 | 32.6 (in the form of multipliers | adders) for C-16QAM and C-64QAM, respectively.

Towards 100 Gbps over 100m MMF using a 850nm VCSEL

Employing MultiCAP signaling, successful 70.4 Gbps transmission over 100 m of OM3 MMF using off-the-shelf 850 nm VCSEL with 10.1 GHz 3-dB bandwidth is experimentally demonstrated indicating the feasibility of achieving 100 Gbps with a single 25 GHz VCSEL.

Quad-polarization transmission for high-capacity IM/DD links

We report the first experimental demonstration of IM/DD links using four states of polarization. Fiber-Induced polarization rotation is compensated with a simple tracking algorithm operating on the Stokes space. The principle is proven at 128 Gb/s over 2-km SSMF.

Rate equation-based phase recovery for semiconductor laser coherent transmitters

We present a novel carrier recovery technique for coherent systems with semiconductor lasers that incorporates the laser dynamics. A sensitivity improvement of 8dB over a decision-directed phase-locked loop is achieved experimentally for 28GBd DP-16QAM.

Laser Rate Equation-Based Filtering for Carrier Recovery in Characterization and Communication

We formulate a semiconductor laser rate equation-based approach to carrier recovery in a Bayesian filtering framework. Filter stability and the effect of model inaccuracies (unknown or unuseable rate equation coefficients) are discussed. Two potential application areas are explored: Laser characterization and carrier recovery in coherent communication. Two rate equation-based Bayesian filters, the particle filter and extended Kalman filter, are used in conjunction with a coherent receiver to measure frequency noise spectrum of a photonic crystal cavity laser with less than 20 nW of fiber-coupled output power. The extended Kalman filter is also used to recover a 28-GBd DP-16 QAM signal where a decision-directed phase-locked loop fails.

Phase noise tolerant carrier recovery scheme for 28 Gbaud circular 16QAM

We propose a novel carrier phase recovery scheme for circular 16QAM coherent transmission systems. Experimental results show low penalties (<;1.4 dB) even for linewidths where square 16QAM exhibits irretrievable (above the FEC limit) error floor.