Limitations on Gain in Rare-Earth Doped Fiber Amplifiers due to Amplified Spontaneous Emission

Yu. A. Varaksa, George V. Sinitsyn, Mikhail A. Khodasevich

MONTECCHI M., SETTEMBRE M., TAMBURRINI M. +2 more

Sik Heng Foo

J. Bai, E. Towe

This paper discusses a unified method for modeling and simulating signal light amplification in rare-earth doped optical fiber amplifiers. The model accounts for gain saturation, spontaneous emission, dispersion, and nonlinear effects along the length of the distributed gain medium. Simulations based on the unified model are shown to compare favorably with experimental results. The new model can be used to provide guidance in the design and construction of a variety of fiber-based optical amplifiers. Furthermore, it is suitable for analyzing the performance of high-power amplifiers in a wide range of operating conditions.

Balakrishnan Sridhar

A complete experimental and theoretical study of rare earth doped fiber-optic amplifiers for the first tele-communication window has been made. The thulium doped fluoride fiber amplifier is shown to provide amplification in the 800nm-820nm signal region. A complete steady state theoretical model has been presented and the model has been experimentally verified. The model predicts the gain, noise figure and the amplified spontaneous emission in the 800nm, 1470nm, 1900nm and 2300nm bands. The effect of population trapping at the $\\sp3F\\sb4$ energy level of thulium ion is also shown with the help of the model. It has been shown that about 5-15%o of the population is trapped at the $\\sp3F\\sb4$ energy level. We have also shown theoretically, the expected gain and noise performance of Thulium doped fluoride fiber amplifiers pumped in the 680nm absorption band. The maximum gain at 806nm is slightly lower than with comparable 780 nm pumping. The gain bandwidth is however found to increase with 680nm pumping. The higher ASE at shorter wavelengths ($<$806nm) reduces the gain at the peak wavelength (806nm). This is a result of the better inversion with three level pumping at 680nm as compared to two level resonant pumping at 780nm. We report an efficient single mode erbium doped flouride fiber amplifier in the 850nm signal band for the first time. The amplification is through an up-conversion process. The erbium doped flouride fiber amplifier was pumped with an estimated pump power of 35mW at 792nm. We have also considered a theoretical model for a single mode erbium doped fluoride fiber amplifier. Efficient amplification occurs because of the strong excited state absorption at the pump wavelength from the $\\sp4I\\sb{13/2}$ energy level.

Emir Salih Magden, Patrick T. Callahan, Nanxi Li +12 more

The spontaneous emission lifetime in Al2O3:Tm3+ waveguides is measured to be 568 ± 48 µs, using a frequency-domain method. The method is studied and verified in Er3+-doped silica fiber, yielding a measured lifetime of 9.73 ± 0.08 ms.