Paul F. Wysocki

24-line multiwavelength operation of erbium-doped fiber-ring laser

Simultaneous lasing at up to 24 wavelengths is demonstrated in an erbium-doped fiber-ring laser using a simple design. This result is achieved using a low-loss cavity, controlled polarization evolution and liquid nitrogen cooling to enhance spectral hole-burning, polarization hole-burning, and polarization selectivity. The design does not include any wavelength-selective components; instead, it utilizes wavelength selectivity provided by polarization evolution in the cavity. The amplitude variation between emission peaks is less than 3 dB over a 17-nm spectral range. A narrow linewidth of 0.15 nm, dense line spacing of 1.1 nm, and a good signal-to-noise ratio of more than 30 dB are achieved over most of the erbium bandwidth. The comb spectrum location and width are adjustable by changing and adjusting cavity components.

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.

High Reliability 49 dB Gain, 13W PM Fiber Amplifier at 1550 nm with 30 dB PER and Record Efficiency

We present a single-mode, polarization-maintaining, Er/Yb-codoped cladding-pumped amplifier with up to 49 dB of gain, 13W output power, a 30 dB polarization-extinction ratio, 12.9% electrical to optical conversion efficiency, and 42% optical-optical power-stage fiber slope efficiency. This is the most efficient highest PER HPOA ever reported near 1550 nm. The HPOA was built using all fiber-based components qualifiable for long missions in harsh environments.

Simple modeling approach for the temperature dependence of the gain of erbium-doped fiber amplifiers

In many practical wavelength-division multiplexed (WDM) systems, erbium-doped fiber amplifiers (EDFA) must maintain a flat gain spectrum over a broad bandwidth for a wide temperature range. When the flatness specification is tight, the temperature dependence of the erbium ion spectra is too great to allow flatness over a wide range of temperatures. To date, all observed temperature variation data has been for specific EDFA designs and no simple rule has been developed for extending the observations to a wide range of EDFAs. We show that the gain and absorption parameters of an erbium- doped fiber follow easily fit dependencies on temperature. Consequently, the change in an EDFA spectrum with temperature can be easily predicted by use of a computer model or sometimes by direct computations using the known dependencies. Physical insight into the meaning of the dependencies is presented and predictions for typical EDFAs are shown.

Polarization effects in polarization-independent and polarization maintaining fiber amplifiers

Polarization effects in fiber optical amplifiers are described. Theoretical and experimental results for the statistical variation of the polarization extinction ratio (PER) in a PM amplifier are presented. PER variation between units and over temperature is analyzed

L-band erbium-doped silica fibers and their applications

High concentration erbium-doped silica fibers were developed for amplification of L-band optical signals. Power conversion efficiency as a function of erbium-doping concentration for various erbium-doped silica fibers was analyzed and characterized at a wavelength of 1585 nm and at a pump wavelength of 1480 nm by using a two-stage amplifier and a C-band ASE filter. The experimental results are consistent with the simulation results. High Al doping and optimization of NA and erbium-doped region can help reduce the pair-induced quenching effects and improve the efficiency.