Optimization of the power ratios of the bidirectional pumping at two wavelengths for erbium-doped fiber amplifiers

The gain and noise factor spectra of erbium-doped fiber amplifiers with pumped according to a copropagating three-level scheme and according to a counterpropagating quasi-two-level scheme in the regime of unsaturated gain in the C band have been simulated numerically. It has been shown that, at the total pump power up to 30 mW and at the optimized power ratio of the copropagating and counterpropagating pumps, the inhomogeneity of the gain in the C band does not exceed 0.25 dB at the noise factor of 4.2–4.7 dB.     

Transmission capacity of erbium-doped fiber amplifiers as a criterion for quality of erbium-doped optical fibers

A new criterion—transmission capacity in the unsaturated gain regime—is proposed for comparing the quality of glasses for erbium-doped fiber amplifiers, considered as an element of an optical communication system. It is shown that, according to the criterion for the highest transmission capacity, amplifiers based on alumino-phosphate-silicate and zinc-sodium-germanate-silicate fibers are preferred for systems with separate C and L bands, respectively. In broadband systems, the highest transmission capacity is observed in amplifiers based on tellurite fibers.     

Radiation Polarization Distribution Function of a Dye Laser

The Fokker–Planck equation for the distribution function of the intensity of an individual component has been solved in the approximation of the Ornstein–Uhlenbeck process within the framework of the formalism of the method of polarization components. Based on this solution, we have constructed the distribution functions of the degree of lasing radiation polarization, analyzed experimental data for a certain geometry of laser pumping, and determined the values of the distribution parameters, including the loss coefficients for the polarization component.     

Calibration of Temperature from the Fluorescence Spectra of Lead–Fluoride Glass Doped with Erbium

Optics and Spectroscopy - Multivariate methods are applied to the calibration of temperature in the range from 299 to 423 K for the green fluorescence spectra of erbium in...     

Spectral efficiency of information transfer by erbium-doped fiber amplifiers in the unsaturated gain regime

The results of numerical simulation of the ultimate spectral efficiency of information transfer by erbium-doped fiber amplifiers in the S and C bands in the regime of unsaturated gain are presented. The cases of co-and counterpropagating pumps are analyzed in terms of the three-level and quasi-two-level schemes. It is shown that, for the peak gain in the range 12–24 dB and a signal-to-noise ratio at the entrance equal to 20 dB, the ultimate efficiency lies in the range 5.5–7.5 bit s^?1 Hz^?1 for the S band and 5.6–7.2 bit s^?1 Hz^?1 for the C band.     

Statistical Properties of the Polarized Radiation of a Dye–Solution Laser

Within the framework of the method of polarization components we obtained the Fokker–Planck equation for the intensity–distribution function of an individual component. Solutions for the Ornstein–Uhlenbeck process show that the experimentally observed special features in the behavior of the distribution function of the intensity and degree of polarization of laser radiation in the vicinity of the threshold are well described in the approximation of statistical independence of polarization components. However, since the Ornstein–Uhlenbeck process includes states not realizable physically for the given case, an exact solution of the Fokker–Planck equation is constructed by the method of expansion in eigenstates. It is shown that this solution is totally correct physically and yields virtually the same values for the distribution functions of the intensity and degree of polarization of radiation as the dependences obtained earlier for the Ornstein–Uhlenbeck process.     

Modeling the gain and amplified spontaneous emission spectra of erbium-doped fiber amplifiers

We have used a modified “black box” model to calculate the gain and amplified spontaneous emission spectra for an erbium-doped fiber amplifier. Based on this and using an occupation number model, we determined the limiting spectral efficiency of information transfer in such an amplifier. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 273–276, March–April, 2006.     

Glasses for erbium-doped fiber amplifiers: A comparison based on the ultimate spectral efficiency of information transmission

A new figure of merit—the ultimate spectral efficiency of information transmission in the regime of unsaturated gain in the case of a quasi-two-level scheme of pumping—is proposed to compare host glasses for erbium-doped fiber amplifiers (EDFAs) that are considered as a constituent of an optical communication system. It is shown that the amplifiers based on silicate glasses possess the best characteristics, whereas the amplifiers based on phosphate and tellurite glasses have somewhat worse and substantially worse characteristics, respectively.     

Adsorption of tentacled tetragonal star connectors, C4R4-Co-C5(HgX)5, on mercury

For future use in self-assembly of surface structures, the adsorption on the surface of mercury of a series of tetraphenylcyclobutadienecyclopentadienylcobalt double-decker sandwich complexes with five mercury and sulfur containing "tentacles" on the cyclopentadienyl deck has been examined by combined electrochemical and Langmuir trough techniques.     

Spectral luminescence and information characteristics of transparent lead fluoride nano-glass-ceramics doped with erbium ions

Spectral luminescence properties of synthesized transparent nano-glass-ceramics doped with erbium ions are studied. It is shown that, as a result of the secondary heat treatment of nano-glass-ceramics, the width of the luminescence spectrum at half maximum increases more than by 15 nm. Luminescence life-time dependences of erbium ions in studied samples are measured, their absorption cross-sections are determined, and their emission cross-sections are calculated by the McCumber method. Spectral and ultimate information characteristics of erbium-doped fiber amplifiers based on synthesized nano-glass-ceramics are numerically simulated. It is shown that, in the unsaturated gain regime, a substantial ripple of the absorption and emission cross-section spectra and shorter lifetime of the metastable level of the erbium ion reduce the pumping radiation power that is required for obtaining the given peak gain, narrow the gain spectra, and lower the transmission capacity of devices based on nano-glass-ceramics compared to the initial glass. Conversely, fiber amplifiers based on calcium fluoride glass-ceramics, for which the lifetime of the metastable level increases with increasing annealing temperature, have an advantage in the transmission capacity over devices based on the primary glass.