Bismuth doped fiber laser and study of unsaturable loss and pump induced absorption in laser performance

Kalita, Mridu P.; Yoo, Seongwoo; Sahu, J.K.

doi:10.1364/oe.16.021032

Cited by 97 publications

(43 citation statements)

References 11 publications

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“…Bismuth is a polyvalent element with four oxidation states: Bi 51 , Bi 31 , Bi 21 and Bi 1 . Two processes take place in molten polyvalent element-doped glass: oxidation (at a higher valence state) and reduction (at a lower valence state).…”

Section: Nature Of Bi-related Near-ir-emitting Centersmentioning

confidence: 99%

“…It is well-known that Bi 31 and Bi 21 ions emit visible luminescence and no near-IR luminescence. [9][10][11][12] .…”

Section: Nature Of Bi-related Near-ir-emitting Centersmentioning

confidence: 99%

“…The results of early investigations of the transmission and luminescence properties of various Bi-doped fibers are presented in a number of reviews and papers (see, for example Refs. [28][29][30][31][32].…”

Section: Near-ir Luminescence Properties Of Bi-doped Optical Fibersmentioning

confidence: 99%

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Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers

2012

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It has recently been demonstrated that Bi-doped glass optical fibers are a promising active laser medium. Various types of Bi-doped optical fibers have been developed and used to construct Bi-doped fiber lasers and optical amplifiers. This paper reviews the recent results regarding the luminescence properties of various Bi-doped optical fibers and the development of Bi-doped fiber lasers and optical amplifiers for the 1150 to 1550 nm spectral region.

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Section: Nature Of Bi-related Near-ir-emitting Centersmentioning

confidence: 99%

“…It is well-known that Bi 31 and Bi 21 ions emit visible luminescence and no near-IR luminescence. [9][10][11][12] .…”

Section: Nature Of Bi-related Near-ir-emitting Centersmentioning

confidence: 99%

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Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers

2012

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“…These unique luminescent properties indicate that Bi-doped glasses are good candidates for an ultrabroadband lasing application at unconventional wavelengths and for tunable lasers. Previously, a novel fiber laser material based on Bi-doped silica glass emitting in the NIR region garnered a lot of attention [15][16][17][18][19][20][21][22]. However, the doping concentrations of Bi in silica glass are low (normally less than 0.1 mol%), the preform is fabricated at a high temperature (about 2000°C) with heavy volatility of Bi, and the emission bandwidths of the fibers are narrower than that of Bi-doped bulk glasses.…”

Section: Introductionmentioning

confidence: 99%

Bismuth-doped glass microsphere lasers

et al. 2017

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In this work, a hybrid structure consisting of a multicomponent germanate glass microsphere containing bismuth as a gain medium is proposed and presented. The bismuth-doped germanate glass microspheres were fabricated from a glass fiber tip with no precipitation of the bismuth metal. Coupling with a fiber taper, the bismuth-doped microsphere single-mode laser was observed to lase at around 1305.8 nm using 808 nm excitation. The low threshold of absorbed pump power at 215 μW makes this microlaser appealing for various applications, including tunable lasers for a range of purposes in telecommunication, biomedical, and optical information processing.

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“…However, the poor lasing efficiency of BiDF laser, compared to the widely used rare-earth doped fiber lasers, requires further investigations. One possible reason that can impair the BiDF laser efficiency is the presence of high unsaturable loss in the fiber, which is temperature dependent [1,2]. Thus, temperature rise in the BiDF under strong pumping can be a limiting factor for such laser systems.…”

mentioning

confidence: 99%

Bismuth doped fiber laser performance on effective fiber cooling

Kalita

Yoo

Sahu

2009

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference

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In the past, bismuth doped fiber (BiDF) lasers, operating in the 1160 -1300 nm wavelength range, have gained much attention as they are promising for many applications; including medical and astronomy. However, the poor lasing efficiency of BiDF laser, compared to the widely used rare-earth doped fiber lasers, requires further investigations. One possible reason that can impair the BiDF laser efficiency is the presence of high unsaturable loss in the fiber, which is temperature dependent [1,2]. Thus, temperature rise in the BiDF under strong pumping can be a limiting factor for such laser systems. Here, we report the dependence of BiDF laser efficiency on effective cooling of the fiber.The fiber laser was constructed with a 30 m long BiDF in a 100%-4% linear cavity, where a 15 W Yb doped fiber laser at 1090 nm served as the pump source. We used a broadband mirror in the high reflection end of the fiber to reflect back both pump and signal. The fiber had an absorption coefficient of 1.04 dB/m at 1090 nm and 0.23 dB/m at 1178 nm; measured by the cut-back method. The fiber core was 8 µm with a NA of 0.18, and the outer diameter was 125 µm.Figure 1(a) shows the BiDF laser output power in various heat sink arrangements. We found that at high pump powers the laser efficiency decreased when the fiber was cooled by natural convection. The rollover in output power was prominent at approximately 6 W of pump power at 24 0 C. An increase in fiber temperature was also observed during the experiment. To verify our results, the fiber temperature was further increased to 40 o C in air. A similar behaviour was observed and the efficiency dropped down to 2%. To provide more effective heat removal from the fiber, the fiber spool was then placed in a water tank at room temperature. An increase in efficiency, compared to that measured at room temperature, was observed with the water cooling. Moreover, no rollover in the output power was noticed. On further cooling the fiber to 10 o C in water, an increase in efficiency upto 10% was observed. We also raised the water temperature to 40 o C, and the efficiency dropped down to 4.8%, but no rollover was observed in the output power even at the maximum pump power. We further measured the unsaturable loss in our BiDF at the pump wavelength of 1090 nm, and at different temperatures [ Fig.1 (b)]. The fiber was dipped in water, so as to maintain the same temperature during the entire experiment. The ratio of unsaturable absorption to small signal absorption was 33, 30 and 28% at 40 o C, 20 o C and 10 o C respectively. It seems to indicate that, the gradual increase in fiber temperature with the pump power, in absence of forced cooling [Air-24 0 C and Air-40 0 C; both in Fig 1(a)], leads to a continuous rise in unsaturable loss in the BiDF, resulting in rollover in the 1178 nm output power. Thus, with effective cooling the BiDF laser performance can be significantly improved. References[1] M. P. Kalita, S. Yoo, and J. Sahu, "Bismuth doped fiber laser and study of unsaturable loss and pump indu...

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Bismuth doped fiber laser and study of unsaturable loss and pump induced absorption in laser performance

Cited by 97 publications

References 11 publications

Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers

Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers

Bismuth-doped glass microsphere lasers

Bismuth doped fiber laser performance on effective fiber cooling

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