Jacopo Nanni

Digital predistortion technique for the compensation of nonlinear effects in radio over fiber links

Due to their inherent capillary distribution properties, Radio over Fiber (RoF) systems are expected to play a major role within future fifth generation wireless networks. However, significant bounds on the technology usability are set by the nonlinear generation of spurious frequencies, which, in the case of RoF links exploiting Directly Modulated Lasers (DML), has the combined effect of laser chirp and optical fiber dispersion among its prevailing causes. In this paper, a signal digital predistortion system, which can lower these detrimental effects, is proposed in two different versions. A detailed description of its functional model is given, and its attractive features in terms of quality improvement of the received signal is illustrated.

Modal Noise Mitigation in 850-nm VCSEL-Based Transmission Systems Over Single-Mode Fiber

Various short-range optical connections, transmitting either high-bit-rate digital signals or radio frequency analog signals, can exploit 850-nm vertical-cavity surface-emitting lasers as optical source together with the standard single-mode fiber (SSMF) as optical channel. This solution presents attractive features in terms of reduced cost and energy consumption. However, bandwidth reduction due to intermodal dispersion and undesired fluctuations of the received signal due to modal noise are present in this case. Such effects are studied theoretically and experimentally, and a cost-effective solution is proposed to reduce their impact. Hence, connections with SSMF length up to 300 m with 3-dB bandwidth of 2500 MHz are demonstrated, while the modal noise is reduced to a standard deviation of less than 2 dB.

Tyrosine Kinase Inhibitors (TKI) in Relapsed/Refractory (RR) Patients with FLT3-ITD Positive Acute Myeloid Leukemia (AML) Confer Better Survival than Chemotherapy, Due to a Better Safety Profile

S200 will be efficacious in treating in vivo murine leukemias that are currently in development. The next phase of this project will aim to determine mechanisms of sensitivity and resistance to PARP inhibition in AML.

VCSEL-SSMF-based Radio-over-Fiber link for low cost and low consumption wireless dense networks

This paper presents a possible Radio-over-Fiber (RoF) system which can be implemented in current and next generations of cellular networks such as LTE or future 5G. The system proposed is based on low cost and low consumption optical components such as 850 nm Single Mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fiber (SSMF) of G.652 type. The performances are evaluated through the computation of the Error Vector Magnitude (EVM) for an entire LTE frame of 10 ms for 20 MHz band signal in band 20 of the standard. Appropriate countermeasures were adopted against the bandwidth reduction due to the behavior of the G.652 fiber, which in the first optical window stops to exhibit monomodality. This allowed to achieve high modulation format transmission is done for various input RF powers and for distances stretching up to 1.5 Km.

Chirp evaluation of semiconductor DFB lasers through a simple Interferometry-Based (IB) technique

Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results.