Jose Estaran

High-Speed 1550 nm VCSEL Data Transmission Link Employing 25 GBd 4-PAM Modulation and Hard Decision Forward Error Correction

Current short-range optical interconnects capacity is moving from 100 to 400 Gb/s and beyond. Direct modulation of several laser sources is used to minimize bandwidth limitations of current optical and electrical components. This total capacity is provided either by wavelength division multiplexing or parallel optics; it is important to investigate on the ultimate transmission capabilities of each laser source to facilitate current capacity standards and allow for future demands. High-speed four-level pulse amplitude modulation at 25 GBd of a 1.5 μ m vertical-cavity surface-emitting laser (VCSEL) is presented in this paper. The 20 GHz 3 dB-bandwidth laser is, at the time of submission, the largest bandwidth of a 1.5 μ m VCSEL ever reported. Forward error correction (FEC) is implemented to achieve transmission over 100 m virtually error free after FEC decoding. Line rate of 100 Gb/s is achieved by emulation polarization multiplexing using 50 Gb/s signal obtained from a single VCSEL.

100 Gb/s single VCSEL data transmission link

100 Gb/s optical fiber transmission link with a single 1.5 um VCSEL has been experimentally demonstrated using 4-level pulse amplitude modulation.

Application of Machine Learning Techniques for Amplitude and Phase Noise Characterization

In this paper, tools from machine learning community, such as Bayesian filtering and expectation maximization parameter estimation, are presented and employed for laser amplitude and phase noise characterization. We show that phase noise estimation based on Bayesian filtering outperforms conventional time-domain approach in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated for the first time experimentally.

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.

Joint Iterative Carrier Synchronization and Signal Detection Employing Expectation Maximization

In this paper, joint estimation of carrier frequency, phase, signal means and noise variance, in a maximum likelihood sense, is performed iteratively by employing expectation maximization. The parameter estimation is soft decision driven and allows joint carrier synchronization and data detection. The algorithm is tested in a mixed line rate optical transmission scenario employing dual polarization 448 Gb/s 16-QAM signal surrounded by eight on-off keying channels in a 50 GHz grid. It is shown that joint carrier synchronization and data detection are more robust towards optical transmitter impairments and nonlinear phase noise, compared to digital phase-locked loop (PLL) followed by hard decisions. Additionally, soft decision driven joint carrier synchronization and detection offers an improvement of 0.5 dB in terms of input power compared to hard decision digital PLL based carrier synchronization and demodulation.

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.

Bayesian filtering for phase noise characterization and carrier synchronization of up to 192 Gb/s PDM 64-QAM

We show that phase noise estimation based on Bayesian filtering outperforms conventional time-domain approaches in the presence of moderate measurement noise. Additionally, carrier synchronization based on Bayesian filtering, in combination with expectation maximization, is demonstrated for the first time experimentally.

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.

Focusing Over Optical Fiber Using Time Reversal

A time-reversal array in multimode fiber is proposed for lossless remotely controlled switching using passive optical splitters. The signal to be transmitted is digitally predistorted so that it is routed through the physical layer in order to arrive at only one receiver in an array. The system performance in the presence of an additive white Gaussian noise, modal group delay, and timing error is investigated numerically for single-mode fiber and 10-mode fiber. Focusing using a two-transmitter array and 44 km of single-mode fiber is demonstrated experimentally for 3-GBd QPSK signals with a bit error rate below the forward error correction limit.