| Novel end-pumping method for double-clad fiber amplifiers and lasers |
| Pavel Peterka, Ph.D.; Ivan Kašík, Ph.D.; Vlastimil Matějec, Ph.D.; Jiří Slánička |
| Year: 2006 |
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Fiber amplifiers are used in optical communications for compensation
of signal losses in a transmission fiber. The invention of a
cladding-pump technique enabled significant increase of the output
powers of both fiber amplifiers and lasers. In these devices pump
light of a high-power, but low-brightness, laser diode enters the
large area of the inner cladding of a double-clad (DC) fiber and is
gradually absorbed by rare-earth ions incorporated into a thin core of
the DC fiber. The signal guided in the core is amplified via
stimulated emission of the excited rare-earth ions. DC fibers are
remarkably efficient at converting the output of high-power,
low-brightness diode lasers into high-power, high-brightness beams. DC
fiber lasers are replacing conventional solid-state lasers in many
medium- and high-power applications.
We have proposed a novel pumping scheme for DC-fibers and demonstrated its application in a fiber laser [1, 2] and amplifier [3]. The pumping scheme is based on a unique patented design [4] where the pump and signal fibers are spliced directly to a DC fiber with a specifically tailored cross-section. This DC fiber also provides optimum absorption of the pump along the fiber. Moreover, the shape of the DC fiber resembles the cross sections of the pump and signal fibers as much as possible to facilitate their splicing. The developed fiber amplifier module does not require any bulk or intermediate fiber coupling elements as it does most other clad-pumped devices. The splicing of the pump and signal fibers to the DC fiber can be done using commercial fusion splicer in an automated process with low losses for both the pump and the signal. Therefore we anticipate that the presented DC fiber module can find applications in cost-effective high-power fiber devices. 
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