Francesca Parmigiani

Ultra-flat SPM-broadened spectra in a highly nonlinear fiber using parabolic pulses formed in a fiber Bragg grating

We propose a new method for generating flat self-phase modulation (SPM)-broadened spectra based on seeding a highly nonlinear fiber (HNLF) with chirp-free parabolic pulses generated using linear pulse shaping in a superstructured fiber Bragg grating (SSFBG). We show that the use of grating reshaped parabolic pulses allows substantially better performance in terms of the extent of SPM-based spectral broadening and flatness relative to conventional hyperbolic secant (sech) pulses. We demonstrate both numerically and experimentally the generation of SPM-broadened pulses centred at 1542 nm with 92% of the pulse energy remaining within the 29 nm 3 dB spectral bandwidth. Applications in spectra slicing and pulse compression are demonstrated.

Single-laser 32.5 Tbit/s Nyquist WDM transmission

Single-laser 32.5 Tbit/s 16QAM Nyquist-WDM transmission with 325 carriers over 227 km at a net spectral efficiency of 6.4 bit/s/Hz is reported.

Parabolic pulse evolution in normally dispersive fiber amplifiers preceding the similariton formation regime

We show analytically and numerically that parabolic pulses and similaritons are not always synonyms and that a self-phase modulation amplification regime precedes the self-similar evolution. Properties of the recompressed pulses after SPM amplification are investigated.

Single source optical OFDM transmitter and optical FFT receiver demonstrated at line rates of 5.4 and 10.8 Tbit/s

OFDM data with line rates of 5.4 Tbit/s or 10.8 Tbit/s are generated and decoded with a new real-time all-optical FFT receiver. Each of 75 carriers of a comb source is encoded with 18 GBd QPSK or 16-QAM.

Phase sensitive amplification based on quadratic cascading in a periodically poled lithium niobate waveguide.

We propose and demonstrate phase-sensitive amplification based on cascaded second harmonic generation and difference frequency generation within a periodically poled lithium niobate waveguide. Excellent agreement between our numerical simulations and proof-of-principle experiments using a 3-cm waveguide device operating at wavelengths around 1550 nm is obtained. Our experiments confirm the validity and practicality of the approach and illustrate the broad gain bandwidths achievable. Additional simulation results show that the maximum gain/attenuation factor increases quadratically with input pump power, reaching a value of +/- 19.0 dB at input pump powers of 33 dBm for a 3 cm-long waveguide. Increased gains/reduced powers for a fixed gain could be achieved using longer crystals.

First demonstration of all-optical QPSK signal regeneration in a novel multi-format phase sensitive amplifier

We propose a novel black-box optical phase sensitive amplifier (PSA) configuration and describe its application to the regeneration of multi-level phase encoded signals. The concept is demonstrated with a 10 Gbaud quadrature phase shift keyed (QPSK) input.

Pulse retiming based on XPM using parabolic pulses formed in a fiber Bragg grating

We experimentally demonstrate a novel all-optical all-fiberized pulse retiming scheme incorporating parabolic pulses generated in a linear fashion through pulse shaping in a superstructured fiber Bragg grating. The scheme relies on chirping the signal to be retimed using cross-phase modulation with the broader parabolic clock pulses, and subsequently retiming it through linear propagation in a dispersive medium. We demonstrate the cancellation of up to 4-ps root-mean-square timing jitter for /spl sim/2-ps data.

Demonstration of amplified data transmission at 2 µm in a low-loss wide bandwidth hollow core photonic bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fibers low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008 nm over 290 m of 19 cell HC-PBGF is reported.

Detailed characterization of a fiber-optic parametric amplifier in phase-sensitive and phase-insensitive operation

We experimentally demonstrate a single-pumped, non-degenerate phase-sensitive parametric amplifier with a precise control of phase and amplitude of the in-going waves and investigate in detail its gain, attenuation and saturation properties in comparison with operation in phase insensitive amplifier (PIA) mode. We experimentally observe the variation of the gain and attenuation as a function of the relative phase, pump power and the signal-idler power ratio. The phase sensitive gain spectrum is studied over a 24 nm symmetrical bandwidth and we achieve a maximum phase sensitive amplification (PSA) gain of 33 dB. A departure from the theoretical maximum attenuation as the gain increases is observed and explained.

Errata to “All-Optical Pulse Reshaping and Retiming Systems Incorporating Pulse Shaping Fiber Bragg Grating”

This paper demonstrates two optical pulse retiming and reshaping systems incorporating superstructured fiber Bragg gratings (SSFBGs) as pulse shaping elements. A rectangular switching window is implemented to avoid conversion of the timing jitter on the original data pulses into pulse amplitude noise at the output of a nonlinear optical switch. In a first configuration, the rectangular pulse generator is used at the (low power) data input to a nonlinear optical loop mirror (NOLM) to perform retiming of an incident noisy data signal using a clean local clock signal to control the switch. In a second configuration, the authors further amplify the data signal and use it to switch a (low power) clean local clock signal. The S-shaped nonlinear characteristic of the NOLM results in this instance in a reduction of both timing and amplitude jitter on the data signal. The underlying technologies required for the implementation of this technique are such that an upgrade of the scheme for the regeneration of ultrahigh bit rate signals at data rates in excess of 320 Gb/s should be achievable.