頻譜可調摻鉺光纖鎖模雷射

Mode-locked erbium-doped fiber laser with tunable intracavity spectral modulation

陳弘文

指導教授 ： 楊尚達

國立清華大學/電機資訊學院/光電工程研究所/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00268

摘要

光纖鎖模雷射具有許多優點因此近年來受到廣泛的發展。自相似雷射以及全正色散光纖雷射所使用的新鎖模機制使得輸出脈衝能量與一般被動鎖模飛秒光纖雷射相比提升了十倍以上。在本論文中，我們展示了一組中心波長位於1.55微米且共振腔內具有強正色散的摻鉺光纖共振器。在共振腔內我們導入了一組傅立葉轉換脈衝塑形器使得雷射的頻寬與中心波長具有大幅的可調性。由脈衝塑形器提供的額外群延遲色散有效地提升脈衝能量以及降低輸出脈衝的非線性啁啾。輸出脈衝能量在無碎波狀態下能藉由額外的群延遲色散由4.3奈焦耳提升至8.9奈焦耳，並只受限於可得的最大幫浦功率(320毫瓦)。脈衝寬度與脈衝序列的穩定性藉由脈衝強度自相關量測、頻率解析光柵量測、示波器脈衝軌跡與無線電頻率頻譜量測來進行分析。此外，超連續光源頻譜介於1200奈米至2400奈米之間可以由一段15公尺的高度非線性光纖產生。

關鍵字

超快光學 ； 飛秒光纖鎖模雷射 ； 非線性光學

並列摘要

Mode-locked fiber lasers have been extensively explored in recent years because of a variety of practical advantages. The new mode-locking mechanisms of self-similar and all normal dispersion fiber lasers increase the output pulse energy by more than one order of magnitude for the passively mode-locked femtosecond fiber lasers. In this thesis, we demonstrate an erbium-doped fiber oscillator with predominant normal group delay cavity dispersion (GDD) at 1.55 wavelength. A Fourier transform pulse shaper built into the cavity enables the central wavelength and bandwidth of the fiber oscillator to be widely tunable. An extra GDD introduced by the shaper effectively increases the pulse energy and reduces the nonlinear chirp of the output mode-locked pulse. The wave-breaking-free output pulse energy can be increased from 4.3 nJ to 8.9 nJ by adding an extra GDD of 0.178 ps2, limited by the available pump power of 320 mW. The pulse width and stability of the pulse train were thoroughly characterized by intensity autocorrelation, frequency-resolved optical gating, oscilloscope trace, and radio-frequency spectral analysis. Besides, supercontinuum generation from 1200 nm to 2400 nm was generated by a 15-m-long highly nonlinear fiber.

參考文獻

[1] K. Yamakawa and C. P. J. Barty, "Ultrafast, Ultrahigh-Peak, and High-Average Power Ti:Sapphire Laser System and Its Applications," IEEE Journal of Selected Topics in Quantum Electronics, 6, 658-675 (2000).

[2] D. H. Sutter, I. D. Jung, F. X. Kartner, N. Matuschek, F. Morier-Genoud, V. Scheuer, M. Tilsch, T. Tschudi, and U. Keller, " Self-Starting 6.5-fs Pulses from a Ti:Sapphire Laser Using a Semiconductor Saturable Absorber and Double-Chirped Mirrors," IEEE Journal of Selected Topics in Quantum Electronics, 4, 169-178 (1998).

[4] J. An, D. Kim, J. Dawson, M. J. Messerly and P. J. Barty, "Grating-less, fiber-based oscillator that generates 25 nJ pulses at 80 MHz, compressible to 150 fs," Optics Letters, 32, 2010-2012 (2007).

[5] H. G. Liu, J. H. Huang, J. H. Li, W. Weng, H. Zheng, Y. Ge, S. T. Dai, F. Shi, "Above 100 nJ all-normal-dispersion femtosecond pulse generation from a large-core multi-mode fiber laser," Laser Physics Letters, 10, 055101 (2013).

[7] F. W. Wise, A. Chong, and W. H. Renninger, "High-energy femtosecond fiber lasers based on pulse propagation at normal dispersion," Laser & Photonics Reviews, 2, 58–73 (2008).