Gain Spectral Filtering for Spectral Enhancement of Mode-Locked Fiber Oscillators
Spectral enhancement of a mode-locked fiber oscillator has been proposed by using gain spectral filtering technique. A wide spectral width of 83 nm at 1030 nm, with 5.2 nJ pulse energy was achieved with positive net cavity dispersion. Fiber oscillator output spectrum was analyzed numerically, showin...
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| Published in: | Japanese Journal of Applied Physics Vol. 52; no. 12; pp. 122701 - 122701-5 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Japan Society of Applied Physics
01-12-2013
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Spectral enhancement of a mode-locked fiber oscillator has been proposed by using gain spectral filtering technique. A wide spectral width of 83 nm at 1030 nm, with 5.2 nJ pulse energy was achieved with positive net cavity dispersion. Fiber oscillator output spectrum was analyzed numerically, showing larger gain spectral filtering effect in longer gain medium systems. We show that the gain spectral filtering plays the same role as spectral filter element inside the resonator, hence could replace it in dispersion managed lasers improving the output spectrum and simplifying fiber oscillator designs. |
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| Bibliography: | Calculated normalized spectral bandwidth and required net cavity dispersion $D_{\text{n}}$ versus the length of the gain medium of a fiber oscillator. The SPM and SAM coefficients were set at $\delta = 5 \times 10^{-3}$ W -1 m -1 and $\gamma = 3 \times 10^{-4}$ W -1 m -1 , respectively. It was used well known coefficient of Yb doped fiber for SPM coefficient, SAM coefficient was selected with below 10% of SPM by considering gain bandwidth limitation of fiber and gain value which was used in numerical calculation which will be discussed in later. (a) Linear dependence of the total SPM ($\Delta$) on the length of the gain medium and constant SAM ($3 \times 10^{-4}$ W -1 ), (b) Linear dependences of both, total SPM ($\Delta$) and SAM ($\Gamma$) on the length of the gain medium. (Color online) Schematic diagram explaining the reconstruction of the temporally chirped pulse by gain medium: (a) temporally chirped pulse induced by large material dispersion, (b) changed temporal shape of the pulse after the gain medium, it was imaged that pulse was grown and pulse edge was clipped due to the gain filtering effect (gain narrowing effect and bandwidth limitation of the gain fiber). (Color online) Simulation results of equilibrated spectral distribution inside the cavity for the case of 1 m length gain medium system: (a) spectral distribution at equilibrium inside the cavity, (b) spectral shapes at specific positions (1), (2), and (3) indicated in (a). (Color online) Simulation results of equilibrated spectral distribution inside the cavity for the case of 1.5 m long gain medium system: (a) spectral distribution at equilibrium inside the cavity, (b) spectral shapes at specific positions (1), (2), and (3) shown in (a). (Color online) (a) Schematic diagram of the fiber oscillator system. (b) Wavelength spectrum of 1 m long gain medium system. (c) Wavelength spectrum of 1.5 m long gain medium system. (Color online) The measured temporal profile and Fourier transform limited pulse profile from spectrum depending on each system (a) 1 m gain medium system, (b) 1.5 m long gain medium system. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.7567/JJAP.52.122701 |