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Optimization of Yb-free Er-doped fiber for lasers and amplifiers cladding pumped at 976 nm was performed in this Letter. The single-mode fiber design includes an increased core diameter of 34 μm and properly chosen erbium and co-dopant concentrations. We demonstrate an all-fiber high power laser and power amplifier based on this fiber with the record slope efficiency of 40%. To the best of our knowledge, the achieved output power of 75 W is the highest power reported for such lasers.

An emission band with a maximum at 1430 nm and a FWHM of 100 nm was observed in a Bi-doped fiber under core-pumping in the 1340- 1370 nm wavelength range. Net gain in 1430-1490 nm and laser action in 1443-1459 nm wavelength range in the Bi-doped aluminosilicate fiber have been demonstrated for the first time to our knowledge.

The characteristics of a device developed for measuring the angular distribution of the intensity of the output radiation of optical fibers in the far field are described. The device’s angular translation stage is controlled through a standard parallel port of a personal computer, and the experimental data are acquired and digitized using a standard sound card. The dynamic range of measurements is>50 dB. Examples of measurements performed with this device for single-mode optical fibers of several types are presented. Good agreement between the calculated and experimental data is demonstrated. The effect of the dynamic range of measurements in the far field on the accuracy of calculating the mode field distribution was investigated. [ABSTRACT FROM AUTHOR]