The gain degradation behavior of erbium-doped fiber amplifiers (EDFA) in a master oscillator power amplifier (MOPA) configuration was characterized using the fibers irradiated with varying irradiation dosages from our in-house Co60-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist for erbium-doped fibers with relatively low concentrations of the co-dopants cerium and germanium added. For fibers with relatively high concentrations of germanium and comparable levels of cerium co-dopants, highly effective radiation hard behavior is exhibited, which is attributed to germanium alone. A fiber optimized for efficiency also provides a radiation-hard EDFA where after a 100-kRad (1000 Gy) exposure, the degradation in signal gain was 5 dB at a MOPA pump power of 315 mW.
We have studied the effect of radiation-induced degradation (RIGD) and recovery of the output optical power for erbium-doped fiber amplifiers (EDFAs) in a master oscillator power amplifier (MOPA) setup before and after radiation exposure using a 60Co gamma-ray source. Our preliminary results indicate that the fibers that are not optimized have a complete degradation of gain after exposure to a 10 kRad (100 Gy) dose, where all input signal power is absorbed. We present our efforts where we have improved the degradation to values where the fibers have a significant reduction in gain degradation after exposure. Results of our efforts for further improvement will be discussed.
The behavior of erbium doped fiber amplifiers (EDFA) in a master oscillator power amplifier (MOPA) configuration was characterized using a 60Co γ-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist for erbium doped fibers with relatively low concentrations of the co-dopants cerium and germanium added. For fibers with relatively high concentrations of germanium and comparable levels of cerium co-dopants highly effective radiation hard behavior is exhibited. A fiber optimized for efficiency also provides a radiation hard EDFA where after a 100 kRad (1000 Gy) exposure, the degradation in signal gain was only 5 dB at a MOPA pump power of 315 mW.
The behavior of erbium doped fiber amplifiers (EDFA) in a master oscillator power amplifier configuration was characterized, for the first time, in-situ using a Co60 γ-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist. A fiber optimized for efficiency also provides a radiation harder EDFA with reduced power degradation after a 10 kRad (100 Gy) exposure.
Rare-earth-doped fibers with single-crystal cores have the potential for 10x higher TMI threshold than their glass counterparts and are a promising candidate for use as gain media in high-power laser systems. Their utility has been limited by parasitic optical losses and difficulty in fabrication. This paper explores methods to reduce the losses in these fibers in the core, in the cladding and at the core-cladding interface and an overview of the work done at NRL in this area.
Recent progress on the procurement, purification, and sintering of a variety of high temperature transparent ceramics is presented. There are numerous applications operating in very harsh environments that require rugged windows. Oxide materials such as Y2O3 and non-oxides such as cubic β-SiC are prime candidates for these applications due to high mechanical strength, good transmission range, and isotropic structure. To fabricate a high transparency window, phase and chemically pure powder precursors must be obtained. Higher purity β-SiC powders are becoming commercially available and multiple sources are analyzed, purified, and sintered to optimize transmission. Both oxide and non-oxide materials are sintered via spark plasma sintering (SPS) and the optical and physical properties are discussed.
Rare-earth-doped fibers with single-crystal cores have the potential for 10x higher TMI threshold than their glass counterparts and are a promising candidate for use as gain media in high-power laser systems. Their utility has been limited by parasitic optical losses and difficulty in fabrication. This paper explores methods to reduce the losses in these fibers in the core, in the cladding and at the core-cladding interface. Fabrication methods are also discussed.
Rare-earth-doped fibers with single-crystal cores have the potential for 10x higher TMI threshold than their glass counterparts and are a promising candidate for use as gain media in high-power laser systems. Their utility has been limited by parasitic optical losses and difficulty in fabrication. This paper explores methods of fabrication of the fibers including core growth via LHPG and application of cladding materials.
In recent years, ceramic sesquioxide materials have emerged as a promising alternative to crystalline laser hosts for near- and mid-infrared laser applications. Ceramics offer a number of manufacturing advantages over crystals including lower fabrication temperatures and the amenability to forming much larger size samples. In this work, a number of RE ions, doped into multiple sesquioxide hosts, are spectroscopically characterized in order to assess their potential for near- and mid-infrared laser applications. Characterization methods included absorption and fluorescence spectroscopy as well as decay dynamics, all measured as functions of temperature. The results are analyzed in order to determine the best laser gain media in the near- and mid-infrared spectral regions.
Rare-earth-doped fibers with single-crystal cores have the potential for 10x higher TMI threshold than their glass counterparts and are a promising candidate for use as gain media in high-power laser systems. Their utility has been limited by parasitic optical losses and difficulty in fabrication. This paper explores methods to reduce the losses in these fibers in the core, in the cladding and at the core-cladding interface. Fabrication methods are also discussed.
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