Dual-stage erbium-doped, erbium/ytterbium-codoped fiber amplifier with up to +26-dBm output power and a 17-nm flat spectrum.

By concatenating an aluminum-codoped erbium-doped fiber with an efficient erbium/ytterbium-codoped fiber, we produce a gain spectrum that is f lat within 0.5 dB for 17 nm from 1544 to 1561 nm. By using energy transfer between erbium and ytterbium ions, we are able to pump the second stage with a high-power 1064-nm source to achieve an output power as high as +26 dBm. Using 980-nm pumping of the first stage, we produce an overall noise figure below 5 dB.

Modeling of ion pairs in erbium-doped fiber amplifiers.

The effects of Er-Er pairs on the characteristics of Er-doped fiber amplifiers are analyzed theoretically. Pairs are found to have little effect on the amplifier optimum length, signal saturation power, and noise figure (at constant gain) but to cause significant reduction in the gain, even at residual levels, quantitatively consistent with fiber laser measurements. A maximum tolerable fraction of paired ions near 8%, corresponding to approximately 400 mole parts in 10(6) Er(2)O(3), is predicted for near-optimum gain efficiency in Al-Ge silica fibers.

Wavelength stability of a high-output, broadband, Er-doped superfluorescent fiber source pumped near 980 nm.

We report the dependence of the mean wavelength of Er-doped superfluorescent fiber sources on temperature, pump wavelength, and pump power. In particular, we measure an intrinsic temperature coefficient of between -2 and +8 parts in 10(6) (ppm) per degree Celsius depending on pump wavelength, pump power, and fiber length. Additionally, we report a pump wavelength dependence that is symmetrical about the peak pump absorption wavelength (near 976 nm) and a decrease in mean wavelength with pump power with a slope of between 0 and -93 ppm/mW.

Electronically tunable, 1.55-microm erbium-doped fiber laser.

An erbium-doped, silica-based fiber laser was electronically tuned over two ranges from 1529.6 to 1533.3 nm and from 1543.8 to 1563.0 nm with more than 13 mW of maximum power. The tuning element was an intracavity acousto-optic modulator (Bragg cell) configured to feed back the first-order, frequency-shifted deflected beam. The maximum optical/acoustic tuning coefficient was -15 nm/MHz.

Broad-spectrum, wavelength-swept, erbium-doped fiber laser at 1.55 microm.

We describe an argon-ion-laser-pumped erbium-doped fiber laser at 1.55 microm that incorporates low-rate frequency modulation of an intracavity acousto-optic modulator to provide repeated, continuous tuning of the output spectrum. The spectral width of this wavelength-swept fiber laser is as large as 20 nm with 9 mW of output power, even though erbium in silica has a mostly homogeneously broadened gain. The time-averaged visibility curve for a 14-nm-wide source indicates a short (160-microm) coherence length, which is of interest for fiber-optic gyroscopes that operate with long integration times and short-coherence-length sources.