Yves Painchaud

100-Gb/s DQPSK Transmission: From Laboratory Experiments to Field Trials

We discuss the generation, detection, and long-haul transmission of single-polarization differential quadrature phase shift keying (DQPSK) signals at a line rate of 53.5 Gbaud to support a net information bit rate of 100 Gb/s. In the laboratory, we demonstrate 10-channel wavelength-division multiplexed (WDM) point-to-point transmission over 2000 km on a 150-GHz WDM grid, and 1200-km optically routed networking including 6 reconfigurable optical add/drop multiplexers (ROADMs) on a 100-GHz grid. We then report transmission over the commercial, 50-GHz spaced long-haul optical transport platform LambdaXtremereg. In a straight-line laboratory testbed, we demonstrate single-channel 700-km transmission, including an intermediate ROADM. On a field-deployed, live traffic bearing Verizon installation between Tampa and Miami, Florida, we achieve 500-km transmission, with no changes to the commercial system hardware or software and with 6 dB system margin. On the same operational system, we finally demonstrate 100-Gb/s DQPSK encoding on a field-programmable gate array (FPGA) and the transmission of real-time video traffic.

Experimental study of 112 Gb/s short reach transmission employing PAM formats and SiP intensity modulator at 1.3 μm

We present a Silicon Photonic (SiP) intensity modulator operating at 1.3 μm with pulse amplitude modulation formats for short reach transmission employing a digital to analog converter for the RF signal generator, enabling pulse shaping and precompensation of the transmitters frequency response. Details of the SiP Mach-Zehnder interfometer are presented. We study the system performance at various bit rates, PAM orders and propagation distances. To the best of our knowledge, we report the first demonstration of a 112 Gb/s transmission over 10 km of SMF fiber operating below pre-FEC BER threshold of 3.8 × 10(-3) employing PAM-8 at 37.4 Gbaud using a fully packaged SiP modulator. An analytical model for the Q-factor metric applicable for multilevel PAM-N signaling is derived and accurately experimentally verified in the case of Gaussian noise limited detection. System performance is experimentally investigated and it is demonstrated that PAM order selection can be optimally chosen as a function of the desired throughput. We demonstrate the ability of the proposed transmitter to exhibit software-defined transmission for short reach applications by selecting PAM order, symbol rate and pulse shape.

Performance of balanced detection in a coherent receiver.

The quality of balanced detection in a coherent receiver is analyzed theoretically and experimentally. The impact of the characteristics of the optics on the balanced detection is presented. A parameter that characterizes the performance of the balanced detection suitable for the whole optical front-end is propose.

Multi-channel fiber Bragg gratings for dispersion and slope compensation

We have demonstrated the fabrication of multichannel fibre Bragg gratings (FBGs) in which the dispersion and the central wavelength are adjusted in each channel. The multi-channel character is achieved by superimposing many gratings on a section of an optical fiber. The adjustment of the central wavelength is precise within /spl plusmn/10 pm. The precision of the dispersion adjustment is close to /spl plusmn/2% which renders possible third-order dispersion compensation.

Fabrication and characterization of a solid polyurethane phantom for optical imaging through scattering media

A phantom based on a polyurethane system that replicates the optical properties of tissue for use in near-infrared imaging is described. The absorption properties of tissue are simulated by a dye that absorbs in the near infrared, and the scattering properties are simulated by TiO2 particles. The scattering and absorption coefficients of the plastic were measured with a new technique based on time-resolved transmission through two slabs of materials that have different thicknesses. An image of a representative phantom was obtained from time-gated transmission.

Apodized Silicon-on-Insulator Bragg Gratings

An accurate control of the apodization profile is still an issue for integrated Bragg grating filters fabricated in silicon-on-insulator because of the high modal confinement of these waveguides. In this letter, we present two fabrication-friendly apodization techniques that are compatible with deep UV lithography and can be used in mass-production of photonic-integrated circuits. These techniques are reliable even for weak effective index modulation amplitude, thus opening the door to the fabrication of long and elaborate grating structures.

Multi-channel notch filter based on a phase-shifted phase-only sampled fiber Bragg graing

We propose a novel method for the implementation of a tunable multi-channel notch filter based on a thermally induced phase-shift phase-only sampled fiber Bragg grating (FBG). The proposed method is numerically and experimentally demonstrated. A 51-channel notch filter with a bandwidth (FWHM) of 0.026 nm and a tuning range of 0.6 nm has been achieved. This proposed technique offers the potential applications to the multiwavelength fiber laser and multi-channel all optical logic devices.

Transmission of 107-Gb/s DQPSK over Verizon 504-km Commercial LambdaXtreme® Transport System

A 107-Gb/s field trial was conducted on a traffic carrying long-haul LambdaXtreme® transport platform over an active 504-km Verizon route in Florida thus proving upgradeability to 100 G of the Alcatel-Lucent 50-GHz spaced ULH DWDM system.

Impact of Sidewall Roughness on Integrated Bragg Gratings

A major issue in the fabrication of integrated Bragg grating (IBG) filters in highly confined waveguides is the average effective index fluctuations caused by sidewall roughness. In this work, we model the impact of this effect on IBG spectral responses and we identify key parameters that need to be controlled in order to minimize distortions. We show that only low spatial frequency components of the noise are relevant to the calculation of the IBG spectral response, which decreases considerably the computation time. Furthermore, we present an IBG emulator that allows estimation of expected fabrication yield of specific gratings given that the fabrication process is well characterized. The analysis of apodized gratings is used as an example to illustrate how this modeling can help to reduce development cost by first studying robustness of IBG designs to fabrication limitations. Finally, we study analytically the impact of sidewall roughness having short correlation lengths and small roughness variances on the spectral response of weak gratings.

Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency.

Coupling of light to and from integrated optical circuits has been recognized as a major practical challenge since the early years of photonics. The coupling is particularly difficult for high index contrast waveguides such as silicon-on-insulator, since the cross-sectional area of silicon wire waveguides is more than two orders of magnitude smaller than that of a standard single-mode fiber. Here, we experimentally demonstrate unprecedented control over the light coupling between the optical fiber and silicon chip by constructing the nanophotonic coupler with ultra-high coupling efficiency simultaneously for both transverse electric and transverse magnetic polarizations. We specifically demonstrate a subwavelength refractive index engineered nanostructure to mitigate loss and wavelength resonances by suppressing diffraction effects, enabling a coupling efficiency over 92% (0.32 dB) and polarization independent operation for a broad spectral range exceeding 100 nm.