脈衝於色散遞增光纖傳遞達大倍率頻譜壓縮

Large-scale Laser Spectral Compression through pulse propagation in a Dispersion-Increasing Fiber

趙婉恬(Wan-Tien Chao)

指導教授 ： 黃承彬

國立清華大學/電機資訊學院/光電工程研究所/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00015

摘要

光脈衝頻譜壓縮可有效增加頻譜亮度，即有效提升訊雜比，因此有助於光譜學上的應用與發展。光脈衝在標準單模光纖之頻譜壓縮現象於1978年提出，並於1993年有明確的物理解釋，指出頻譜壓縮主要為自相位調變作用於負啁啾脈衝。
本論文頻譜壓縮系統為傳統絕熱系統光孤子脈衝壓縮的反向操作，並用一線性色散遞增光纖達成頻譜壓縮結果。由於在絕熱系統光孤子壓縮理論下，頻譜壓縮比受限於光纖條件，但本論文模擬分析顯示真實頻譜壓縮可以超越光纖條件限制。在實驗上，證實半高寬為112飛秒鎖模雷射脈衝頻譜壓縮比為28.6倍，並超越本實驗室光纖理想壓縮比22.5倍。
近年來，開始探討波形相關的頻譜壓縮可能性。本論文分析各種波形的頻譜壓縮可能性，模擬結果顯示正色散光纖雷射脈衝對比於雙曲正切與高斯脈衝，擁有較高頻譜壓縮比，並使用本實驗室架設之全正色散光纖雷射作為光源，於實驗上得到頻譜壓縮比高達45倍之結果。

關鍵字

光孤子 ； 頻譜壓縮 ； 非線性效應

並列摘要

The optical sources with high spectral brightness enhance the signal-to-noise ratio which is helpful in spectroscopic application. The spectral compression in a single mode fiber was first observed and it was later satisfactorily explained where the cause of spectral narrowing was attributed to self-phase modulation acting on a negative-chirped pulse.
Our approach for spectral compression is using a linear ramp dispersion-increasing fiber (DIF), which is reverse processes of adiabatic soliton temporal compression. However, the feasibility for spectral compression would be seemingly limited by the dispersion ramp of DIF. In our numerical analysis, it would be possible that the real spectral compression ratio exceeds the ideal fiber limitation. In experiment, we prove that a stretch-pulse mode locked fiber laser with 112fs pulse width reaches the spectral compression ratio of 28.6 which the number is beyond ideal ratio of 22.5.
Recently, the waveform-dependent spectral compression within a normal dispersive photonic crystal fiber was addressed. In our calculation, we analyze the feasibility for spectral compression over various waveform pulses and point out that all-normal dispersion (ANDi) fiber laser pulses could give higher spectral compression ratio than hyperbolic secant and Gaussian pulses. Using a home-made ANDi laser as optical source, the spectral compression ratio of 45 can be achieved experimentally.

並列關鍵字

soliton ； spectral compression ； nonlinear effect

參考文獻

[1]R. H. Stolen and C. Lin, "Self-phase-modulation in silica optical fibers," Physical Review A, vol. 17, pp. 1448-1453, 1978 1978.

[2]S. A. Planas, N. L. P. Mansur, C. H. B. Cruz, and H. L. Fragnito, "Spectral narrowing in the propagation of chirped pulses in single-mode fibers " Optics Letters, vol. 18, pp. 699-701, May 1 1993.

[3]M. Oberthaler and R. A. Hopfel, "Special narrowing of ultrashort laser-pulses by self-phase modulation in optical fibers " Applied Physics Letters, vol. 63, pp. 1017-1019, Aug 23 1993.

[4]S. Shen, C. C. Chang, H. P. Sardesai, V. Binjrajka, and A. M. Weiner, "Effects of self-phase modulation on sub-500 fs pulse transmission over dispersion compensated fiber links," Journal of Lightwave Technology, vol. 17, pp. 452-461, Mar 1999.

[5]B. R. Washburn, J. A. Buck, and S. E. Ralph, "Transform-limited spectral compression due to self-phase modulation in fibers," Optics Letters, vol. 25, pp. 445-447, Apr 1 2000.