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1.
The effect of absorber saturation on pulse shaping was studied both numerically and experimentally in a semiconductor disk laser. It was found that steady-state mode locking can be achieved even with very weak saturation of the absorber when the pulse energy is well below the saturation energy of absorption. The study discloses for the first time the direct impact of absorber modulation depth on the pulse width. Numerical analysis confirms that partial bleaching of absorption is adequate for formation of stable mode locking in SDLs. The fast gain dynamics of the semiconductor medium approach the dynamics of a slow gain medium at low pulse energies and high repetition rates with a pulse period much shorter than the gain recovery time. The presented results are of practical importance for multigigahertz repetition rate lasers, indicating that sufficient pulse shaping can occur when the saturable absorber is not fully bleached. 相似文献
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YUAN Xiao DING Guilin LIU Jingru LAU¨U Baida Julius Goldhar Physics Department Sichuan University Chengdu China Northwest Institute of Nuclear Technology P.O.Box Xi''''an China 《Chinese Journal of Lasers》2001,10(5):333-336
1 Introduction Inrecentyearstherehasbeenanintensiveeffortdirectedtowardtheproductionofshortpulse,high powerUVlasersystems .KrFlaser,withits~ 2nmbandwidth ,highelectrical to opticalconversionefficiencyanditsunbound groundstate ,isanattractivecandidateforthe… 相似文献
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A simple 10 ps KrF laser system consisting of quenched dye laser oscillator pumped by a XeCl laser, a distributed feedback dye laser (DFDL), a three-stage dye amplifier and a two-stage KrF amplifier are described. The output of the laser system is 140 mJ with 10 ps pulse width by using polarization-multiplexing amplification. A focused output laser intensity of about 4×1015 W/cm2 is obtained. The saturation fluence for KrF laser is obtained with this laser. 相似文献
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A new mode-locking method of tunable dye laser is described. This simple and practical method requires only an external intensity modulator to the pumping source. After the simple analytical considerations, the experimental work was done using an Ar laser pumped Rhodamin 6G dye laser and an acousto-optic modulator. As results, stable continuous trains of mode-locked pulses were obtained throughout in the ordinary lasing range 570–630 nm. The pulse width, estimated to be 30–50 ps by SHG autocorrelation measurements, is limited by the bandwidth of Lyot filter used. It is also shown experimentally that this method can be applicable for the suppression of the growth of double pulses in passive mode-locking with saturable absorber (DODCI). 相似文献
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J. Hebling 《Applied physics. B, Lasers and optics》1988,47(3):267-272
The behaviour of an excimer-laser-pumped distributed feedback dye laser (ELP DFDL) using a mixture of saturable absorber and laser dye as an active medium was studied. In a DFDL self-Q-switching occurs because of the population inversion dependence of the feedback. If the DFDL contains absorber saturation of the absorption by the leading edge of the created laser pulse also causes Q-switching. As a result of this double self-Q-switching, mixing a saturable absorber into the laser dye, the laser pulses become shorter and more stable. This was demonstrated experimentally. Mixing Rhodamine B into the dye solution of a Coumarin 153 ELP DFDL, a six-fold reduction in the pulse duration and a more than two-fold reduction in the pulse energy instability were observed. The experimental results were in good qualitative agreement with the predictions of a simple rate equation model. 相似文献
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We have investigated the detailed operation of a frequency modulated dye laser (FML). The FML consists of a standing wave Rh6G dye laser with an intracavity transverse ADP phase modulator which is driven at a frequency close to the cavity mode spacing. An ideal FML output consists of a laser beam which is constant in amplitude but sinusoidally varying in frequency. This provides a source of many laser modes which are equally spaced by the modulation frequency. Several dye laser configurations have been investigated. Measurements of the mode intensities, total power, amplitude modulation and rf beat amplitudes have been made as a function of the rf driving frequency of the phase modulator. The FM laser obtained has been frequency stabilised by locking it to a reference interferometer and also by frequency offset locking it to a single-frequency dye laser. 相似文献
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S. P. Ng D. Y. Tang J. Kong L. J. Qin X. L. Meng Z. J. Xiong 《Applied physics. B, Lasers and optics》2005,81(4):511-515
We report on a diode-pumped passively mode-locked Nd:Gd0.64Y0.36VO4 laser with a Cr4+:YAG saturable absorber. Q-switched mode locking (QML) with 90% modulation depth was obtained. The peak power of the mode-locked pulse near the maximum of the Q-switched envelope was estimated to be about 1.7 MW at the pump power of 12 W. Besides QML, continuous-wave mode locking was also experimentally realized, for the first time to our knowledge, in the laser under a strong intracavity pulse energy fluence. The mode-locked pulse width is about 2.96 ps at a repetition rate of 161.3 MHz. 相似文献
9.
Indium Tin Oxide Coated D-Shape Fiber as a Saturable Absorber for Generating a Dark Pulse Mode-Locked Laser
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B.Nizamani S.Salam A.A.A.Jafry N.M.Zahir N.Jurami M.I.M.Abdul Khudus A.Shuhaimi E.Hanafi S.W.Harun 《中国物理快报》2020,(5):63-66
A dark pulse mode-locked laser is experimentally demonstrated using the indium tin oxide(ITO) coated Dshape fiber as a saturable absorber(SA).Using the polishing wheel technique,a D-shape single mode fiber was fabricated.A 60-nm-thick layer of ITO was deposited over the D-shape fiber using the electron beam deposition method.The SA has a saturation intensity of 40.32 MW/cm2 and a modulation depth of 3.5%.A stable dark pulse mode-locked laser was observed at a central wavelength of 155... 相似文献
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对1560 nm单频光纤激光光源通过一个光学模清洁器后的强度噪声进行了分析研究.实验观察到模清洁器虽然对于激光的高频强度噪声有明显的抑制作用,但强度噪声特性随频率呈一定周期变化,且在低频处模清洁器对强度噪声有放大作用.本文认为这是由于模清洁器具有类似于光纤延迟线的时延效应,将激光源的部分相位噪声转化为强度噪声.通过理论分析,由相位噪声转化的相对强度噪声幅度与激光相干时间、模清洁器的平均延时参数以及分析频率相关.分析结果与实验测量结果符合良好.此外,通过在光路中加入声光调制器进行反馈调制,激光的线宽从26 kHz压窄至16 kHz,模清洁器的锁定质量明显提高,经过模清洁器后的激光强度噪声有所减小,与理论相符.该结果进一步证实了由相位噪声转化而来的强度噪声与模清洁器的锁定质量无直接关系.通过该研究,完善了光学模清洁器对激光的噪声抑制模型. 相似文献
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We demonstrate 60-fs pulses with an average output power of 84 mW from a diode-pumped Nd:glass laser mode locked by a low-finesse antiresonant Fabry-Perot saturable absorber (A-FPSA). The mode-locked spectrum spreads over most of the available Nd:glass fluorescence bandwidth. At increased pulse energy fluence or decreased negative group-velocity dispersion, multiple pulsing was observed. We experimentally characterize this behavior, which can be explained by the saturation behavior of the A-FPSA and the limited available gain bandwidth. These considerations are significant for the design of saturable absorbers to achieve stable passive mode locking. 相似文献
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The critical behavior of passive mode locking has been demonstrated in a figure-eight fiber laser that performs rational harmonic mode locking (RHML). On both the repetition rate and the pulse amplitude distribution, the observed pulse trains near the threshold exhibit the same regulations as the rational harmonic mode-locked ones. The theory also shows that there should be a middle status of RHML before achieving normal mode locking. It is important to note that the results provide what we believe to be the first confirmed attempt to address a fundamental question: how does a laser become mode locking with an increase of pump power? 相似文献
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We have experimentally achieved the 8.3-ps ultra-short pulse at 10 GHz repetition rate with the time jitter as low as 590
fs in an actively mode-locked fiber ring laser. The ring-cavity laser is mode-locked by a semiconductor optical amplifier
based on cross-gain modulation. The external CW source is modulated with radio frequency signal by an amplitude modulator
as the external optical pulses and, then, injected into the fiber ring cavity to achieve active mode locking. Further investigating
the laser output characteristics, it indicates that the linewidth of employed CW source affects properties of the generated
ultra-short pulse, such as phase noise and time jitter. Ultra-short pulse at high repetition rate with low time jitter can
be generated by the optimization of CW laser source. 相似文献
15.
The discovery of a novel phase‐locked frequency comb generated from a monolithic laser with the concurrent processes of self‐mode locking (SML) and stimulated Raman scattering (SRS) is reported. It is experimentally shown that the width of the Raman gain can be exploited to considerably expand the frequency comb of a monolithic SML crystal laser via the SRS process. At a pump power of 6.5 W, an output power of 140 mW in the Stokes wave with a pulse width as narrow as 2.9 ps at a pulse repetition rate of 6.615 GHz is obtained. The present finding not only provides useful insights into the monolithic intracavity SRS process but also paves the way for generating mode‐locked pulses based on monolithic self‐Raman crystals. 相似文献
16.
Ultrafast all-solid-state laser technology 总被引:3,自引:0,他引:3
U. Keller 《Applied physics. B, Lasers and optics》1994,58(5):347-363
Passively mode-locked diode-pumped solid-state lasers can provide practical high-power laser sources with pico- and femtosecond pulse durations. We use semiconductors not only to optically pump but also to cw mode-lock or Q-switch a solid-state laser. A novel saturable absorber design, the Antiresonant Fabry-Perot Saturable Absorber (A-FPSA), allows of using semiconductor saturable-absorber materials even though they are generally not well-matched to the characteristics required for diode-pumped solid-state lasers, i.e., the semiconductors tend to have too much optical loss, a too low saturation intensity, and a too low damage threshold. This paper gives an overview of passively mode-locked ion-doped crystalline solid-state lasers. In particular, we present a quantitative discussion of A-FPSA mode locking, and compare A-FPSA mode locking with other passive mode locking techniques such as KLM (Kerr Lens Mode locking). 相似文献
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Asim Shahzad Muhammad Zafrullah Muhammad Khawar Islam Ramon Maldonado-Basilio Kevin Carney Pascal Landais 《Optik》2014
The quality and pulse compression of the 60 GHz millimeter wave signals generated by 750 μm long InAlGaAs Multi Quantum Well (MQW) passively mode locked laser under free running and optical self-injection locked conditions are experimentally characterized in terms of longitudinal modes under certain bias currents that range from 24 mA to 90 mA. Initially, the MQW laser is characterized in free running condition with no external injection. The measurements reflect that the free spectral range of laser under test is around 61 GHz and exhibit more than 22 lasing modes. The laser is then integrated into low phase noise self-injection locking oscillator by feeding a part of output RF signal back into the laser cavity to enhance passive mode locking. By doing so the microwave line width of our laser is reduced from 900 kHz to 24 kHz with significant increase in output of resultant beat tones which exhibits strong passive mode locking. This is the first time that the free running microwave line width of MQW laser is reduced up to this level. It is evident from our experimental investigation that as we increase the power and phase correlation between different longitudinal modes inside laser cavity through optical self-injection, the strength of the passively mode locked mechanism is significantly increased and the phase noise of radio frequency signal is drastically reduced. 相似文献
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Lian F. Q. Fan Zh. W. Wang X. F. Huang Y. T. Huang K. Ma Y. F. Niu G. Li X. H. Yu J. 《Laser Physics》2011,21(6):1103-1107
In this paper, we describe a compact all-fiber-path picosecond pulse based on Ytterbium doped fiber oscillator. A home-made
novel SESAM mounted on fiber is reported, by which stable mode locking is obtained. The SESAM possesses the low saturation
flux 20 μJ/cm2 (versus prior low saturation flux 32 μJ/cm2), which effectively reduces the pump power threshold of mode locking. The fiber laser generates 15 ps pulse trains without
a dispersive delay line or anomalous dispersion in the cavity. Mode locking pulse with 30 MHz basic repetition-rate was produced,
with 10–30 mW scale average output power at 1064 nm. Through 60 h of uninterrupted laser operating, mode locking is steady
as ever. 相似文献