Dy{sup 3+} - doped chloride crystals have high 1300-nm emission quantum yields. Pump - probe experiments on La Cl{sub 3}:Dy{sup 3+} demonstrate optical gain consistent with predictions based on spectroscopic cross sections and lifetimes.
We propose that Dy/sup 3+/-doped chloride crystals be considered as candidates for amplification of the 1.3 /spl mu/m signal used by the telecommunications network. While several of these types of crystals can provide gain at the specified operating wavelength of 1.31 /spl mu/m, and furthermore offer adequate bandwidth, we have focused our attention on LaCl/sub 3/:Dy as an illustrative case to explore in greater depth. Spectroscopic measurements were made on un-oriented samples of this material; excited-state lifetimes and LaCl/sub 3/:Dy/sup 3+/ Judd-Ofelt parameters are reported. Wavelength-resolved absorption and emission cross sections are presented for the 1.3 /spl mu/m W/spl rlhar2/Z band. Pump-probe measurements (using 0.92 /spl mu/m and 1.32 /spl mu/m, respectively) prove that the observed gain properties of LaCl/sub 3/:Dy are consistent with those predicted on the basis of the spectroscopic cross sections. The Dy:chloride gain media appear to have fundamental optical characteristics amenable to superior 1.3 /spl mu/m telecom amplifier performance, although many fabrication issues would have to be addressed to produce a practical amplifier.
A detailed set of measurements is presented on determining the emission and absorption cross sections of Er/sup 3+/ doped fibers for the /sup 4/I/sub 13/2/ to /sup 4/I/sub 15/2/ transition. Two techniques are employed: the Fuchtbauer-Ladenberg analysis, based on spectroscopic data, and a more direct technique involving optical saturation of the transition. The cross sections, and in particular their ratio, are significantly different for the two techniques. Possible reasons for this are discussed, and it is concluded that the Fuchtbauer-Ladenberg approach is inappropriate in this situation.>
Positive optical gain around 5 cm−1 (∼21 dB/cm) has been observed in Er3+-doped Ba2NaNb5O15 single crystal using a pump and probe experimental setup. High power laser pulses at 532 nm have been used as the pump source in order to strongly populate the S43/2(H211/2) levels of the Er3+ ions due to ground state absorption. Low signal beam cw laser radiation at 850 nm has been used as the probe beam to stimulate the emission associated with the S43/2(H211/2)→I413/2 electronic transition of the Er3+ ions. The process has been modelized as a four level system, and its population has been analyzed and simulated in order to study the gain dynamics. Optical amplification of the probe signal has been observed during the first 60 μs, which represents a good agreement between the measured lifetime of the S43/2(H211/2) levels and the reported simulation.