Very short Er-doped silica glass fiber for L-band amplifiers

Tammela, Simo; Hotoleanu, Mircea; Kiiveri, Pauli; Valkonen, H.; Sarkilahti, S.; Janka, K.

doi:10.1109/ofc.2003.1248276

Cited by 9 publications

(9 citation statements)

References 5 publications

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“…The laser cavity consists of a high-concentration (c Er ¼ 3: 7 10 25 ions=m 3 ) erbiumdoped fiber (5 m, Liekki Er40-4/125), with a Faraday mirror (R ¼ 90%) and a fiber Bragg grating (λ peak ¼ 1556 nm, Δλ 3 dB ¼ 0:2 nm, R ¼ 86%) as reflectors. According to manufacturing data [10] and previous experimental results [11], the short-range coordination order of erbium ions is suppressed and no saturable absorption is present. Total intracavity losses are 5 dB.…”

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confidence: 57%

“…It was also found that suppression of the short-range order leads to improved characteristics of high-concentration erbiumdoped fiber amplifiers and lasers. The suppression can be realized by increasing the solubility of erbium in the host matrix (codoping by Al [9]) or by changing the deposition process (direct nanoparticle deposition [10,11]). Because self-pulsing was observed in HC EDFLs even with these types of fibers, the pair-clusters approach cannot explain this effect [4,5].…”

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confidence: 99%

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Coherence and anticoherence resonance in high-concentration erbium-doped fiber laser

et al. 2010

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We report an experimental study of low-frequency (~10 kHz) self-pulsing of the output intensity in a highconcentration erbium-doped fiber laser. We suggest that the fast intensity fluctuations caused by multimode and polarization instabilities play the role of an external noise source, leading to low-frequency auto-oscillations through a coherence resonance scenario. © 2010 Optical Society of America OCIS codes: 060.3510, 060.2410, 140.3500, 140.1540 Output intensity self-pulsing in high-concentration erbium-doped fiber lasers (HC EDFLs) has been extensively studied for its importance in communications, reflectometry, distributed fiber-optic sensing, biomedicine, etc. [1][2][3][4][5][6][7]. For a long time, the presence of clustered erbium ions and their role as saturable absorber was regarded as the only possible mechanism responsible for self-pulsing at frequencies of 10-100 kHz [7]. However, detailed microscopic study of erbium-doped glasses by means of x-ray-absorption fine structure spectroscopy (XAFS) has revealed a short-range coordination order of erbium ions, rather than pair clustering [8]. It was also found that suppression of the short-range order leads to improved characteristics of high-concentration erbiumdoped fiber amplifiers and lasers. The suppression can be realized by increasing the solubility of erbium in the host matrix (codoping by Al [9]) or by changing the deposition process (direct nanoparticle deposition [10,11]). Because self-pulsing was observed in HC EDFLs even with these types of fibers, the pair-clusters approach cannot explain this effect [4,5]. On the other hand, experiments and theory indicate that the pump-tosignal intensity noise transfer (PSINT) can significantly contribute to low-frequency self-pulsing [4,5]. However, PSINT decreases as the pump current increases, and therefore this process can induce self-pulsing only near the lasing threshold [1,2]. To reveal a mechanism that can drive self-pulsing with pump currents beyond the lasing threshold, we test and experimentally prove the concept of coherence and anticoherence resonance (CR and ACR) [12][13][14]. The details are reported in this Letter. The experimental setup used to study self-pulsing in EDFL is shown in Fig. 1. The laser cavity consists of a high-concentration (c Er ¼ 3:7 10 25 ions=m 3 ) erbiumdoped fiber (5 m, Liekki Er40-4/125), with a Faraday mirror (R ¼ 90%) and a fiber Bragg grating (λ peak ¼ 1556 nm, Δλ 3 dB ¼ 0:2 nm, R ¼ 86%) as reflectors. According to manufacturing data [10] and previous experimental results [11], the short-range coordination order of erbium ions is suppressed and no saturable absorption is present. Total intracavity losses are 5 dB. The Faraday mirror rotates the plane of polarization of the reflected beam by π=2 at λ ¼ 1550 nm. To pump the erbium-doped fiber, we used a 978 nm laser diode (LD) with a tunable current source (200-600 mA). The pump current at the lasing and self-pulsing threshold was 240 mA.To characterize the polarization instability as a possible source of high-fre...

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Coherence and anticoherence resonance in high-concentration erbium-doped fiber laser

et al. 2010

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“…Gain: Saturation signal: 0dBm @1600 Gain difference Figure 4: Small signal gain with 0dBm saturating signal and gain difference with two saturating signal wavelengths 12 The ability to control the local environment of the Er ion also produces broad absorption and emission cross-sections, which can be utilized in L-band amplifiers 12 , lasers 13 and ultra broadband ASE sources 14 . Due to the uniform doping of the fiber there is almost no spectral hole burning in the L-band amplifier, Figure 4.…”

Section: Gain Difference (Db)mentioning

confidence: 99%

The potential of direct nanoparticle deposition for the next generation of optical fibers

et al. 2006

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Fiber lasers offer substantial advantages compared to conventional solid-state lasers due to their high efficiency, compact size, diffraction-limited beam quality, tunability, and facile thermal management. A number of important applications require high peak powers and pulse energies, which has generated great interest in Yb-doped, large-modearea (LMA) fibers. Liekki has pioneered a new manufacturing technology for rare-earth-doped fibers, Direct Nanoparticle Deposition (DND), that is capable of producing fibers uniquely well suited to power scaling. Conventional fiber fabrication methods are characterized by poor process accuracy and flexibility due to the large particle sizes and relatively small number of deposition layers (2-10). In contrast, DND provides independent control of the composition of hundreds of layers that make up the core, thereby allowing previously unattainable precision, accuracy, and uniformity in the index and rare-earth-dopant profiles. DND allows the simultaneous use of both gasphase and liquid precursors, providing unprecedented flexibility in the glass composition. Furthermore, DND enables fabrication of fibers with extremely high rare-earth concentrations, which minimizes the required fiber length and correspondingly raises the threshold power for nonlinear processes. Finally, the single-step, direct-deposition process makes manufacturing of fibers rapid and cost-effective, even for fibers with large core diameters or sophisticated geometries and dopant distributions. DND fibers have shown high conversion efficiency (low clustering), low photodarkening, and high damage threshold. DND thus promises to revolutionize the use of fiber lasers in applications previously restricted to bulk, solid-state lasers and to enable new applications of high-power lasers.

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“…Recently, the investigations of up-conversion processes have attracted great interest in connection with the development of Erbium-doped glasses with high doping concentration of Erbium ions (10 20 -10 21 cm −3 ) for planar amplifiers, and micro-cavity lasers operating at 1550 nm [1][2][3]. In other hand, the conversion of infrared light to visible light through energy up-conversion in rare-earth doped glasses, due to the possibility of infrared-pumped visible lasers, has a great potential application in areas such as optical data storage, lasers, sensors, and optical displays [4][5][6].…”

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confidence: 99%

Effect of Excitation Migration and Upconversion in Highly Erbium-doped Glass Micro-sphere Lasers

Hoi¹,

Huy

Chi

2012

Comm. in Phys.

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Abstract. Excitation migration and upconversion process in the Erbium-doped silica-alumina glass microsphere lasers with concentrations of 2500-4000 ppm were investigated in detail. The experiment shows that under 976 nm excitation, the intense of up-conversion emission at 523, 546 and 657 nm, corresponding to the transitions 2 H 11/2 → 4 I 15/ , 4 S 3/2 → 4 I 15/2 , and 4 F 9/2 → 4 I 15/2 , respectively, depends on the erbium content, migration of excitation and pump power. The excitation migration has strongly influenced on the threshold and Red shift of lasing wavelength and migration-assisted up-conversion process leads to degraded amplification performance of microsphere lasers made by silica-alumina glasses with different contents of Er-ions.

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Very short Er-doped silica glass fiber for L-band amplifiers

Cited by 9 publications

References 5 publications

Coherence and anticoherence resonance in high-concentration erbium-doped fiber laser

Coherence and anticoherence resonance in high-concentration erbium-doped fiber laser

The potential of direct nanoparticle deposition for the next generation of optical fibers

Effect of Excitation Migration and Upconversion in Highly Erbium-doped Glass Micro-sphere Lasers

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