Rolando Patricio Espindola

Broad-band erbium-doped fiber amplifier flattened beyond 40 nm using long-period grating filter

Broad-bandwidth amplification is essential for the construction of high-capacity multichannel communication systems. We describe a silica-based erbium doped fiber amplifier (EDFA) with a flat gain bandwidth exceeding 40 nm. The dual-stage EDFA includes a precisely designed inter-stage long-period fiber grating filter with more than 14-dB peak attenuation. By careful choice of the filter spectrum and fiber lengths, this EDFA is flat to within 1 dB over 40 nm while producing a noise figure below 4.0 dB and nearly +15-dBm output power.

A gain-flattened ultra wide band EDFA for high capacity WDM optical communications systems

An 84 nm gain-flattened ultra wide band erbium-doped silica fiber amplifier for high capacity WDM optical communication systems is demonstrated with a noise figure of 6 dB and an output power of 25 dBm. We demonstrated an ultra wide band EDFA with a two-section, split band structure. The total 3dB bandwidth is 84.3 nm, which should be able to support 100 WDM channels with 100 GHz channel spacing or 200 WDM channels with 50 GHz channel spacing. The split bands allow independent optimization of each band for dispersion compensation and span loss variations.

Transmission of 32-WDM 10-Gb/s channels over 640 km using broad-band, gain-flattened erbium-doped silica fiber amplifiers

We report 640-km transmission of 32 wavelength-division-multiplexed (WDM) 10-Gb/s channels with 100-GHz spacing (covering 25-nm bandwidth) using wide dynamic range, gain-flattened erbium-doped silica fiber amplifiers (EDSFAs) with an optical bandwidth of 35 nm. The EDSFA separation is 80 km, the system gain is 140 dB and the total end of system gain nonuniformity among the 32 channels is 4.9 dB.

Enhanced thermal and magnetic actuations for broad-range tuning of fiber Bragg grating–based reconfigurable add–drop devices

We demonstrate two new approaches to broad-range tuning of fiber Bragg grating devices: amplified thermal tuning and programmable magnetic tuning. The thermal-strain tuning approach employs a novel configuration to amplify thermally induced wavelength shifts by use of a negative thermal-expansion component. The magnetic-strain tuning approach allows programmable and latchable wavelength shifts through magnetic interactions that induce controlled strain on the fiber grating. The advantages and disadvantages of these two techniques are contrasted.

Photosensitivity and grating writing in hydrogen loaded germanosilicate core optical fibers at 325 and 351 nm

A refractive index grating has been side written in the core of a hydrogen loaded germanosilicate optical fiber using a phase mask and 351 nm light from an Ar ion laser, the longest wavelength yet reported, to the best of our knowledge, for a grating of this type. The grating strength was ∼1.25 dB, indicating an index change of ∼2×10−4. The fiber was sensitized by low temperature hydrogen loading followed by a brief exposure to a CO2 laser, resulting in the formation of high levels of germanium–oxygen deficiency centers. Fluorescence changes and UV transmission changes in hydrogen loaded germanosilicate glasses exposed to 325 nm and combined 351/364 nm radiation are also reported.

Dense wavelength-division multiplexed transmission in "zero-dispersion" DSF by means of hybrid Raman/erbium-doped fiber amplifiers

Transmission of 25 and 50 equally 100-GHz and 50-GHz spaced 10-Gb/s (OC-192) channels on the ITU grids is demonstrated over eight and four 83.8-km long spans, respectively, of DSF with the zero-dispersion wavelength within the signal wavelength band. Significant performance improvements are obtained with a pump power of only 440 mW with 55-/spl mu/m/sup 2/ dispersion-shifted fibers because of their relatively high Raman efficiency.

Magnetically tunable fiber Bragg gratings

We believe we report the first demonstration of a broad-range (15.7 nm) tuning of fiber Bragg grating using fast, programmable, and latchable magnetic actuation. A key advantage is that the device requires no power except when shifting wavelengths.

8 x 10 Gb/s 1.3-μm unrepeatered transmission over a distance of 141 km with Raman post- and pre-amplifiers

A repeaterless wavelength-division-multiplexed transmission system operating in the 1.3-/spl mu/m wavelength window is demonstrated by means of discrete Raman fiber amplifiers. The power budget is 45.1 dB, leaving a margin of 1.6 dB for a transmission distance of 141 km. The eight channels, which occupy a wavelength range from 1305.8 to 1311.6 nm, carry data at a rate of 10 Gb/s each. The Raman post- and pre-amplifier both employ a two-stage ring topology, which allows counterpropagating pumping.

Broad-range, latchable reconfiguration of Bragg wavelength in optical gratings

Tunability of optical signal filters such as fiber Bragg gratings is important for high volume data communications. A magnetically tunable and latchable optical fiber Bragg grating structure has been devised, and a fine wavelength control as well as a broad-range wavelength tunability has been demonstrated. A spinodally decomposed, anisotropically elongated microstructure was induced in Fe–Cr–Co alloys to fabricate square-loop, programmable magnets. The adjustable attractive force between the magnetic poles was used to controllably strain the grating and induce a very large shift in the Bragg reflection wavelength by as much as 15 nm (which is equivalent to more than 36-channel span in a high density optical communication system). This novel approach can be useful not only for a variety of optical communication networking applications, but also for imparting latchable reconfiguration of structural periodicity and functional properties in a wide class of materials and devices.

Ultra Wide Band Erbium-Doped Silica Fiber Amplifier with 80 nm of Bandwidth

The design of wavelength-division-multiplexed (WDM) systems and optical networks is currently constrained by the limited bandwidth available from erbium-doped fiber amplifiers (EDFAs) because of their nonuniform gain spectra.