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Effect of absorption recovery in bismuth-doped silica glass at 1450   nm on soliton grouping in fiber laser

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ABSTRACT

Saturable absorption in bismuth-doped glasses was found to have a noticeable influence on soliton interaction and group formation. This phenomenon, observed in 1450 nm mode-locked bismuth-doped fiber laser, shows the distinct feature of the multiple pulse regime, which appears as a stationary pulse group whose length can be spread over the whole cavity length by variation of the pump power and polarization. Pulse positioning within the ensemble depends on the saturation fluence and the relatively fast recovery dynamics of bismuth fiber.

No MeSH data available.


Bismuth-doped fiber characteristics.a - Optical loss in bismuth doped fiber; b - Points - gain in bismuth-doped fiber for different pump powers at wavelength λp ~ 1320 nm. The lines are spline approximation; c – the measurement of saturable absorption.
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f1: Bismuth-doped fiber characteristics.a - Optical loss in bismuth doped fiber; b - Points - gain in bismuth-doped fiber for different pump powers at wavelength λp ~ 1320 nm. The lines are spline approximation; c – the measurement of saturable absorption.

Mentions: The fiber preform was fabricated by the MCVD technique with a bismuth concentration in the fiber core of ≤0.02 at.% and ~5 mol.% of germanium resulting in an index step of Δn = 7 × 10−3. The cut-off wavelength was ~0.9 µm. Absorption and gain spectra obtained for an excitation wavelength of 1320 nm are presented in Fig. 1 (a, b), respectively. The net gain, which peaks at a value of 4.4 dB/m at 1430 nm, is the highest value reported to date for bismuth-doped fiber. The corresponding large value of absorption at 1430 nm could be saturated to a value of 2.8 dB/m by increasing the pump power, as shown in Fig. 1c. The relaxation process of photoluminescence in bismuth-doped fiber frequently exhibits bi-exponential decay1314. The fast recovery component typically varies from hundreds of nanoseconds to a few microseconds, depending on fiber core composition, while the slow recovery factor was found to be around ~ 700 µs. The pulse dynamics were studied in the mode-locked Bi-doped fiber laser shown in Fig. 2. The gain medium was a 4 m-long bismuth-doped fiber pumped by a 1310 nm disk laser through a 1310/1450 nm pump combiner. Mode-locked operation was achieved utilizing a lens-coupled semiconductor saturable absorber mirror (SESAM) (see details in methods) operated as an end reflector in a linear cavity. The other end of the cavity was terminated by a butt-coupled highly reflective broadband mirror. The passive fiber components of the laser were made of standard telecom single-mode fiber. The total cavity length was 11.5 m, resulting in a fundamental repetition rate of 9 MHz and a net cavity dispersion of 0.22 ps/nm.


Effect of absorption recovery in bismuth-doped silica glass at 1450   nm on soliton grouping in fiber laser
Bismuth-doped fiber characteristics.a - Optical loss in bismuth doped fiber; b - Points - gain in bismuth-doped fiber for different pump powers at wavelength λp ~ 1320 nm. The lines are spline approximation; c – the measurement of saturable absorption.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382671&req=5

f1: Bismuth-doped fiber characteristics.a - Optical loss in bismuth doped fiber; b - Points - gain in bismuth-doped fiber for different pump powers at wavelength λp ~ 1320 nm. The lines are spline approximation; c – the measurement of saturable absorption.
Mentions: The fiber preform was fabricated by the MCVD technique with a bismuth concentration in the fiber core of ≤0.02 at.% and ~5 mol.% of germanium resulting in an index step of Δn = 7 × 10−3. The cut-off wavelength was ~0.9 µm. Absorption and gain spectra obtained for an excitation wavelength of 1320 nm are presented in Fig. 1 (a, b), respectively. The net gain, which peaks at a value of 4.4 dB/m at 1430 nm, is the highest value reported to date for bismuth-doped fiber. The corresponding large value of absorption at 1430 nm could be saturated to a value of 2.8 dB/m by increasing the pump power, as shown in Fig. 1c. The relaxation process of photoluminescence in bismuth-doped fiber frequently exhibits bi-exponential decay1314. The fast recovery component typically varies from hundreds of nanoseconds to a few microseconds, depending on fiber core composition, while the slow recovery factor was found to be around ~ 700 µs. The pulse dynamics were studied in the mode-locked Bi-doped fiber laser shown in Fig. 2. The gain medium was a 4 m-long bismuth-doped fiber pumped by a 1310 nm disk laser through a 1310/1450 nm pump combiner. Mode-locked operation was achieved utilizing a lens-coupled semiconductor saturable absorber mirror (SESAM) (see details in methods) operated as an end reflector in a linear cavity. The other end of the cavity was terminated by a butt-coupled highly reflective broadband mirror. The passive fiber components of the laser were made of standard telecom single-mode fiber. The total cavity length was 11.5 m, resulting in a fundamental repetition rate of 9 MHz and a net cavity dispersion of 0.22 ps/nm.

View Article: PubMed Central - PubMed

ABSTRACT

Saturable absorption in bismuth-doped glasses was found to have a noticeable influence on soliton interaction and group formation. This phenomenon, observed in 1450 nm mode-locked bismuth-doped fiber laser, shows the distinct feature of the multiple pulse regime, which appears as a stationary pulse group whose length can be spread over the whole cavity length by variation of the pump power and polarization. Pulse positioning within the ensemble depends on the saturation fluence and the relatively fast recovery dynamics of bismuth fiber.

No MeSH data available.