Pierpaolo Boffi

1550-nm volume holography for optical communication devices

The two-lambda method can provide a strategic approach to implement all-optical devices for communication wavelength division multiplexing (WDM) signal processing based on volume holography. By writing holograms at 488 nm in LiNbO/sub 3/:Fe and reading them in the third window of optical communication systems (1550 nm), the feasibility of WDM demultiplexers and holographic memories for digital bytes is here demonstrated.

Stable 100-Gb/s POLMUX-DQPSK Transmission With Automatic Polarization Stabilization

The reliability of 100-Gb/s polarization-multiplexed return-to-zero differential quadrature phase-shift keying transmission is demonstrated exploiting direct detection and automatic polarization stabilization. We experimentally verified a 2-dB chromatic dispersion tolerance of 100 ps/nm. Long-term stability has also been assessed by sampling the bit-error rate every 3 min over a continuous period of 8 h. Measurements are performed both in back-to-back and after 8.8 km uncompensated standard single-mode fiber, in the presence of a polarization scrambler.

All-optical free-space processing for optical communication signals

All-optical free-space architecture can find many interesting applications in optical communications in case of packet-oriented data processing. An example of an all-optical system able to perform data processing operations is described and experimented. Logic schemes characterized by high modularity and flexibility are reported. An optical implementation is proposed by using an elementary switching unit realized with CdTe:In crystal. The unit is optically controlled and operates with beams at typical communication wavelengths. Preliminary experimentation in ns regime at 1550 nm is shown.

Experimental XPM, SPM, FWM penalty evaluation in very dense WDM optical systems

Experimental SPM, FWM and XPM contributions are separately measured. Evaluation of Q penalties is performed on a 2000-km, 33-GHz, 66-GHz and 100-GHz-spaced DWDM system. XPM is found to be the major constrain.

Real-time 100-Gb/s POLMUX RZ-DQPSK transmission over uncompensated 500 km of SSMF by optical phase conjugation

We present an effective solution for the upgrade of a highly dispersive link to POLMUX RZ-DQPSK 100-Gb/s transmission. Dispersion compensation is obtained by properly inserting a single polarization-insensitive phase-conjugation device along the link.

Endless Polarization Stabilizer for High Bit-rate Polarization-Division Multiplexed Optical Systems

An endless polarization stabilization method is applied to a 40-Gbit/s RZ-DQPSK polarization-division multiplexed optical system. The effectivness of the polarization stabilizer in allowing the polarization demultiplexing of the two orthogonally polarized channels is experimentally verified.

Two-stage Sagnac demultiplexer

Cascading a semiconductor optical amplifier (SOA)-based Sagnac interferometer with a second Sagnac stage allows significant improvement in the overall demultiplexer performance. A theoretical analysis and simulations show that the exploitation of a two-stage architecture results in a demultiplexing window sharpness and time compression. Eye-diagram and Q-factor experimental characterization at 2.5 Gb/s of the demultiplexer is presented, showing a 25% compression in time of the two-stage switching window and a 4.7 Q-factor improvement.

Polarization-independent bidirectional optical switch for communication signals

A 2 X 2 optical switch performing bidirectional cross-bar on optical communication signals at 1550 nm is presented and experimented. The switch is based on electro-optic effect in bulk CdTe crystals. Operation is totally independent by input state of polarization of the optical beams to be addressed. The proposed free-space architecture grants high compactness, reliability and fast response time compared with common switching solutions.

20-Gb/s PolDM Duobinary Transmission Over 350-km SSMF Supported by a Polarization Stabilizer and an Optical Dispersion Compensator

A 20-Gb/s transmission over 350-km standard single-mode fiber exploiting duobinary dispersion robustness and polarization-division multiplexing has been demonstrated. The system performance is evaluated employing an automatic endless polarization stabilizer and a suitably designed transmitter-side optical dispersion compensator.

Programmable fiber Bragg gratings for spectral CDMA

Summary form only given.The employment of optical code-division multiple-access (OCDMA) offers high advantages in allocating bandwidth for bursty access networks, where wide bandwidth services are required. Many different optical CDMA implementations have been proposed. Spectral slicing appears an attractive technique because spectral data encoding provides a large number of simultaneous users and transparency to data format and bit-rate. CDMA realized by using a cascade of fiber Bragg gratings (FBGs) allows to combine all the advantages of spectral encoding with the compactness and robustness of a totally guiding structure without free-space architectures losses. In this paper we experiment on FBG technology in order to realize spectral CDMA with programmable encoding. The cascade of 8 FBGs is used in encoding/decoding operation: each grating can be tuned independently by means of piezoelectric elements in order to program the desired user code.