Alessandro Iocco

Bragg grating fast tunable filter for wavelength division multiplexing

A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems.

CW highly efficient 1.24 /spl mu/m Raman laser based on low-loss phosphosilicate fiber

We report the first demonstration of an extremely simple and efficient 1.24 /spl mu/m phosphosilicate fiber-based Raman laser with Bragg gratings written directly in the fiber used. The laser pumped by Nd fiber laser exhibits a slope efficiency of 80%.

Measurement of stress concentrations using embedded optical fiber Bragg grating sensors

This paper investigates the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure. Due to the nature of a stress concentration (i.e. the strong non-uniformity of the strain field) the assumption that the grating spectrum in reflection remains a single peak with a constant bandwidth may not be valid. Compact tension specimens including a controlled notch shape are fabricated with embedded optical fiber Bragg gratings at identical locations but with different gauge lengths. The spectra in transmission varies between such specimens for given loading conditions. This variation is shown to be due to the difference in gauge length. By using the strain field measured on the specimen surface with electronic speckle pattern interferometry and a discretized model of the grating, the spectra in transmission are then verified analytically. Thus, by considering the non-uniformity of the strain field, the optical fiber Bragg gauge functions well as an embedded strain gauge near the stress concentration. Due to the distributed nature of the measurements within a specific gauge length, the optical fiber Bragg gauge has a large potential to measure debonding in fiber reinforced composites.

Stable and widely tunable all-fiber Pr(3+)-doped cw laser system using fiber Bragg gratings.

A simple and strictly all-fiber 1300-nm cw laser is presented. It is tunable over 16 nm with 0.5-nm linewidth and several milliwatts of output power in the whole tuning range from 1292 to 1308 nm. The setup uses a fiber Bragg grating as a combined tuning element and narrow-band output mirror. The simplicity and stability of this system are due to the following two characteristics: First, polarization control is not necessary anywhere in the system, and second, a wavelength-selective system and a narrow-band mirror are combined into one novel fiber-optic element.

Fast and widely tunable Bragg grating reflection filter

A fiber Bragg grating filter device linearly tunable over 45 nm is presented. The device has a maximum tuning speed of 19 nm/ms with a wavelength setting time below 1.5 ms.

Optical low-coherence reflectometry characterization of cladding modes excited by long-period fiber gratings

The group refractive-index difference of cladding modes excited by a long-period fiber grating is characterized by use of the technique of optical low-coherence reflectometry, with a precision of <10(-4) . Very good agreement between theoretical and experimental results is demonstrated.

OLCR characterization of long period grating induced cladding modes

The group index of well-defined cladding modes has been characterized for the first time to our knowledge by optical low-coherence reflectometry (OLCR) with a precision <10/sup -4/. Very good agreement between theoretical and experimental results has been obtained.