共查询到20条相似文献,搜索用时 31 毫秒
1.
在理论上详细分析了利用非线性光学环形镜(NOLM)来减小输出脉冲幅度波动,消除噪声并对脉冲进行压缩整形的物理机制。在主动锁模掺铒光纤环形激光器中(AHML-EDFL)接入一个非线性光学环形镜,形成结构新颖的主被动锁模掺铒光纤激光器(APHML-EDFL),利用非线性光学环形镜所具有的饱和吸收体功能,成功地制抑了4阶有理数谐波锁模(RHML)中较大的幅度噪声,在1GHz量级的调制频率下,由主被动锁模掺铒光纤激光器获产生重复频率为5.1GHz,幅度相当稳定的4阶有理数谐波锁模脉冲序列。 相似文献
2.
F. Wang D. Z. Zhong Z. M. Wu G. Q. Xia R. F. Li 《International Journal of Infrared and Millimeter Waves》2006,27(12):1595-1601
Based on the self-reproduction theory, a rational harmonic mode-locked semiconductor optical amplifier fiber ring laser was
numerically investigated. The system parameters effects on pulse-amplitude equalization of rational harmonic mode locking
was analyzed and the numerical result shows that the 2∼5 order rational harmonic mode-locked pulse with the small amplitude
ripple can be obtained only by adjusting the system parameters. 相似文献
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We propose a novel technique based on negative impulse modulation for pulse repetition rate multiplication by rational harmonic mode locking with pulse-amplitude-equalized pulses directly from the laser cavity. We have generated a pulse train of 15 GHz with more than 16 dB suppression of unwanted amplitude modulation spurs by using a 1 GHz RF signal. This is the highest suppression ratio for a repetition rate multiplication factor of 15 to our knowledge. 相似文献
5.
The output pulse parameters of a mode-locked Nd:YAG laser with a passive negative feedback element were studied experimentally. The pulse evolution within the train was experimentally recorded using a modified second harmonic generation autocorrelator. By comparing the laser operation with and without an acousto-optic modulator, we found that with the later there is a significant increase in the mode locking probability and the pulse acquires a temporally Gaussian symmetric pulse shape. Further with the active modulator there is a relaxation in alignment tolerances and increase in the range of permissible dye concentrations for stable mode locking. It was also observed that the pulse width of the negative feedback laser depends on the saturation intensity of the mode locking dye and reduces for a dye with higher saturation intensity. The pulse width was also found to reduce linearly as the initial transmission of the dye is reduced. 相似文献
6.
搭建了长腔"8"字型掺铒光纤激光器,并对产生的谐波锁模方波脉冲进行了实验研究.结果表明,该脉冲具有光滑的宽带光谱,示波器上显示为方波脉冲,但自相关迹证实其为类噪声脉冲,即为类噪声方波脉冲;通过调节偏振控制器和泵浦功率等激光器腔内参量,获得了高达5阶的谐波锁模类噪声方波脉冲;该类噪声方波脉冲并非可以无限增大脉冲能量,而是在一定条件下产生脉冲分裂,出现谐波锁模方波脉冲现象. 相似文献
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采用自再现理论,对一种包含两个半导体光放大器的锁模光纤环形激光器进行了数值研究.研究结果表明:为了提高谐波锁模输出脉冲的质量,调制半导体光放大器应当保持高直流偏置,对自发辐射信号进行调制并提供锁模脉冲克服腔损耗所需的增益,而此时的增益半导体光放大器则被低直流偏置充当增益补偿器维持较窄的净增益窗口;与之相反,为了获得振幅均衡的有理数谐波锁模输出脉冲,调制半导体光放大器则应当偏置在较低的电流上,而增益半导体光放大器应当保持较高的偏置电流以提供足够的常量增益克服腔损耗.此外,还必须提高注入光信号的峰值功率. 相似文献
9.
Ultralow noise and supermode suppression in an actively mode-locked external-cavity semiconductor diode ring laser 总被引:1,自引:0,他引:1
We report what is to our knowledge the lowest phase and amplitude noise characteristics achieved to date in a 10-GHz pulse train produced by the active harmonic mode locking of an external-cavity semiconductor diode laser. Supermode noise has also been suppressed below -140 dBc/Hz by use of a high-finesse fiber Fabry-Perot etalon as an intracavity filter. Novel noise sideband measurements that extend to the Nyquist offset frequency suggest a significant advantage in using harmonic (rather than fundamental) mode locking to produce ultralow-noise pulse trains, owing to the relationship between the noise roll-off frequency and the fundamental cavity frequency. 相似文献
10.
In conventional rational harmonic mode-locking, optical pulse trains with the repetition rate of(pn + 1)fc are generated when the modulation frequency of the in-cavity modulator is set at fm=(n + 1/p)fc, where n and p are both integers, fc is the fundamental cavity frequency. In this paper, we report that rational harmonic mode locking phenomenon takes place in the fiber lasers when the modulation frequency is set at fm =(n + 2/p)fc. The pulse generations are experimentally demonstrated when the numerator of the rational corresponds to 2 in 5th and 7th order rational harmonic mode-locking. 相似文献
11.
By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers. 相似文献
12.
We report passive harmonic mode locking of a soliton Yb fiber laser at repetition rates continuously scalable up to 1.5 GHz. The laser generates transform-limited 500 fs pulses, with pulse energies of 30-100 pJ. At the 31st harmonic (1.3 GHz), the cavity supermodes are suppressed by 35 dB, and the pulse-to-pulse timing jitter is 6 ps. 相似文献
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We demonstrate a harmonic mode-locked ytterbium-doped fibre ring laser, which consists of a polarization-sensitive isolator, two polarization controllers, two 976nm laser diodes as the pump source and a two-segment ytterbium-doped fibre. Utilizing an additive pulse mode-locked technique based on nonlinear polarization evolution, the ytterbium-doped fibre laser can operate in mode-locked state by adjusting the position of polarization controllers. The cavity fundamental repetition rate is 23.78 MHz. We also observe the second- and third-harmonic mode locking in the normal dispersion region, and their repetition rates are 47.66 MHz and 71.56 MHz, respectively. Over-driving of the saturable absorber in the harmonic mode-locking pulse is analysed and discussed in detail. 相似文献
15.
Stable multigigahertz pulse-train formation in a short-cavity passively harmonic mode-locked erbium/ytterbium fiber laser 总被引:1,自引:0,他引:1
We demonstrate a short-cavity erbium-ytterbium fiber laser that is passively mode locked by a saturable Bragg reflector with a fundamental repetition rate of 235 MHz . The laser operates in the soliton regime and under passive harmonic mode locking with 11 pulses in the cavity and produces output pulse trains at 2.6 GHz with transform-limited 270-fs pulses and 1.6 mW of average power. Within the cavity the multiple pulses form a stable pattern with fixed, nearly equal pulse-to-pulse temporal spacings, causing the output pulse train to have timing offsets of less than 15 ps. A slow gain-recovery model is proposed to explain the pulse-train self-organization. 相似文献
16.
On the basis of numerical simulation results, we put forward a way to realize harmonic passive mode locking of fiber lasers with an ultrahigh-repetition-rate pulse train. The equidistant distribution of ultrashort pulses filling the total laser cavity is due to bound-soliton mechanisms. In the case of large bound energy, such long soliton trains are very stable and have the ideal periodic structure as a soliton crystal. 相似文献
17.
L. M. Zhao D. Y. Tang T. H. Cheng C. Lu H. Y. Tam X. Q. Fu S. C. Wen 《Optical and Quantum Electronics》2008,40(13):1053-1064
We report on the experimental observation of passive harmonic mode locking of bunches of single-pulse solitons or twin-pulse
solitons in an Erbium-doped fiber ring laser. Experimental investigations on the phenomenon revealed that, although the soliton
interaction between the adjacent single-/twin-pulse solitons in a bunch is weaker than that of the pulse interaction in the
twin-pulse solitons, a soliton bunch could also function as a unit and form the state of passively harmonic mode-locking.
Harmonic mode-locking is one of the intrinsic characteristics of soliton emission in passively mode-locked fiber ring lasers.
It can be formed based on the single-pulse soliton, twin-pulse soliton, or bunch of solitons. 相似文献
18.
《Optics Communications》2004,229(1-6):363-370
We report on the experimental observation of passive harmonic mode locking of twin-pulse solitons in an erbium-doped fiber ring laser. Experimental investigations on the passive harmonic mode locking of both the single-pulse and the twin-pulse solitons revealed that, apart from the gain recovery and acoustically induced soliton interactions, the global soliton interaction mediated through an unstable CW lasing in the laser cavity also plays an important role in the formation of the state in the laser. 相似文献
19.
We report on what we believe to be the first demonstration of active mode locking of an optical parametric oscillator. An acousto-optic modulator is inserted into a nearly degenerate (approximately 1064 nm) and doubly resonant optical parametric oscillator based on periodically poled LiNbO3 and pumped with the second harmonic of a quasi-continuous-wave single-frequency Nd:YAG laser. When the modulation frequency is matched to the free spectral range of the cavity (120 MHz), a pulsed regime is observed, with pulse durations as short as 700 ps. 相似文献
20.
Passive harmonic mode-locking of Er-doped fiber laser using CVD-grown few-layer MoS_2 as a saturable absorber
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《中国物理 B》2015,(8)
Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) method and then transferred onto the end face of a fiber connector to form a fiber-compatible Mo S2SA. The 20 th harmonic modelocked pulses at 216-MHz repetition rate are stably generated with a pulse duration of 1.42 ps and side-mode suppression ratio(SMSR) of 36.1dB. The results confirm that few-layer MoS2 can serve as an effective SA for mode-locked fiber lasers. 相似文献