Valentina Cristofori

Dynamic characterization and amplification of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers

We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain bandwidth both in saturated and unsaturated gain regimes.

Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

This paper reports a comprehensive study of pump-to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT cut-off frequency in typical single-pump FOPAs is around 100-200 GHz. The possibilities to shift this frequency based on dispersion and nonlinearities involved in the parametric gain are discussed. The severe IMT to the signal at low modulation frequencies can be suppressed by more than 50% in the gain saturation regime with respect to the linear gain operation. Experimental results confirm the validity of the numerical study.

Fiber-Optical Parametric Amplification of Sub-Picosecond Pulses for High-Speed Optical Communications

Abstract This article reviews recent results of amplification of short optical pulses using fiber-optical parametric amplifiers. This includes chirped-pulse amplification of 400 fs pulses, error-free amplification of a 640-Gbit/s optical time-division multiplexed signal with less than a 1-dB power penalty, and all-optical phase-preserving amplitude regeneration of a 640-Gbit/s return-to-zero differential phase-shift keying optical time-division multiplexed signal.

Synchronization in a Random Length Ring Network for SDN-Controlled Optical TDM Switching

In this paper we focus on optical time division multiplexed (TDM) switching and its main distinguishing characteristics compared with other optical subwavelength switching technologies.We review and discuss in detail the synchronization requirements that allow for proper switching operation. In addition, we propose a novel synchronization algorithm that enables automatic synchronization of software defined networking controlled all-optical TDM switching nodes connected in a ring network. Besides providing synchronization, the algorithmalso can facilitate dynamic slot size change and failure detection. We experimentally validate the algorithm behavior and achieve correct operation for three different ring lengths. Moreover,we experimentally demonstrate data plane connectivity in a ring network composed of three nodes and show successful wavelength division multiplexing space division multiplexing transmission and switching of data bursts when using the proposed algorithm to provide synchronization.

Experimental investigation of pump-to-signal noise transfer in one-pump phase insensitive fibre optic parametric amplifiers

This paper presents a detailed experimental characterization of the relative intensity noise (RIN) transferred from the pump to the signal in one-pump phase insensitive fibre optic parametric amplifiers. We extend an existing experimental and theoretical work towards higher frequencies, showing for the first time a strong wavelength dependence of the RIN transfer over a 30 GHz modulation frequency range. Good agreement is obtained between the measured RIN transfer and the predictions of a simple theoretical model.

Optical spectral reshaping for directly modulated 4-pulse amplitude modulation signals

The tremendous traffic growth in intra/inter-datacenters requires low-cost high-speed integrated solutions [1]. To enable a significantly reduced footprint directly modulated lasers (DMLs) have been proposed instead of large external modulators. However, it is challenging to use DMLs due to their low dispersion tolerance and limited achievable extinction ratio (ER). A promising solution to this problem is optical spectral reshaping (OSR) since it is possible to increase the dispersion tolerance as well as to enhance the achievable ER for both on-of-keying [2] and 4-pulse amplitude modulation (PAM) [3] signals. However, moving to 4-PAM,many of the impressive demonstrations reported so far rely heavily on off-line digital signal processing (DSP), which increases latency, power consumption and cost. In this talk, we report on (i) a detailed numerical analysis on the complex transfer function of the optical filter for optical spectral reshaping in case of pulse amplitude modulation and(ii) an experimental demonstration of real-time dispersion-uncompensated transmission of 10-GBd and 14-GBd 4-PAM signals up to 10- and 26-km SSMF. This is achieved by combining a commercial 10-Gb/s DML with optical spectral shaping, thus removing the need for any complex off-line DSP and improving dispersion tolerance. These achievements are enabled by OSR based on a passive microring resonator fabricated on the SOI platform [4]. Significant improvement in receiver sensitivities was observed for both a 10-GBd signal after 10-km SSMF transmission and 14-GBd with no penalty after 26-km SSMF transmission.

1.5-μm Directly modulated transmission over 66 km of SSMF with an integrated hybrid III-V/SOI DFB laser

A hybrid III-V/SOI directly modulated DFB laser operating at 1.5 μο is fabricated, showing a side mode suppression ratio above 50 dB and a 3-dB bandwidth of 12 GHz. Error-free transmission (BER<10⁻⁹) at 10 Gb/s over 66-km SSMF is demonstrated without dispersion compensation and FEC.

Dynamic Characterization of Fiber Optical Chirped Pulse Amplification for Sub-ps Pulses

We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation.

Saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fibre optic parametric amplifiers

A numerical and experimental characterization of how signal gain saturation affects the transfer of the intensity modulation of the pump to the signal in single-pump phase-insensitive fibre optic parametric amplifiers is presented.