The influence of bending on the gain spectrum in a depressed-cladding erbium-doped fiber amplifier (EDFA)
has been studied. In particular, by changing the bending diameter, it is possible to translate the amplifier band
from C- to S-band. A 22 dB gain for an input signal power of -15 dBm has been obtained in S-band at 1504
nm and in C-band at 1545 with a bending diameter of 15 cm and 100 cm, respectively. By bending the erbium
doped fiber with two different diameters, it is possible to obtain amplification in a wavelength range between Sand
The paper presents a new line of photonic fibers with reduce dcladding radius that permits to reduce the space occupancy of gain coils, fused fiber devices and fiber pigtails without affecting either the performance or the reliability. The proposed reduced cladding photonic fibers seem an effective answer to the demand for compact optical modules and small form factor amplifiers. Considering the advantages of the reduced cladding approach and that no-drawbacks are foreseeable, 80 microns cladding diameter is likely to become a new standard for all the photonic fibers used within optical modules.
The first on-line detection of cracks generated ina laser cladding process is obtained by a very-sensitiveoptical interferometer. The instrument is based on a homodyneMichelson-type configuration and uses an He-Ne laser assource. The instrumental performances (10 MHz bandwidth, 1Angstrom resolution) are maintained during the in-fieldtrials and confirm the feasibility of using opticalinterferometry in material processing diagnostic.