Analysis of passive additive-pulse mode locking with eigenmodetheory

The equation of motion for the coupled cavities of additive-pulse mode locking is solved by the eigenvalue method. The pulse evolution and self-starting condition for passive operation is analyzed. It is shown that the laser configuration is equivalent to an intracavity interferometer, and a phase modulation across the pulse is the essential element for mode locking. With the method developed, transient pulse evolution of an initial seed pulse can be calculated and thereby optimized. It is found that the pulse shortening rate is linear with respect to the number of round trips. The duration for the initial pulse to shorten to a steady state is proportional to its initial width and inversely proportional to the nonlinear coefficient     

Injection locking of an additive-pulse mode-locked fiber laser

Injection locking is utilized to synchronize an additive-pulse mode-locked fiber laser to an external pulsed 76.0-MHz laser source. The spectral and temporal performance of the additive-pulse mode-locked fiber laser and the required conditioning are discussed. A low-jitter temporal synchronization is achieved     

Harmonic mode locking of the Nd:YAG laser

We present experimental and theoretical results forNth harmonic mode locking of a Nd:YAG laser with an intracavity phase modulator operating atN = 2, 3, 4,and 5 times the fundamentalc/2Lfrequency. The bandwidths of the resulting mode-locked spectra depend upon modulation frequency, modulation depth, and laser cavity losses in good agreement with the Gaussian-pulse analysis of Kuizenga and Siegman [5]. For modulation atN(c/2L)the resulting pulse-repetition frequency is alsoN(c/2L)in all cases. However, in theN = 2case, for example, the mode-locked optical spectrum includes every adjacent axial mode component if the laser rod is located near the center of the laser cavity, but only every other axial mode when the rod is located at the end of the laser cavity. This behavior is explained by a Lamb-type theoretical analysis taking into account the competition between the two "hypermodes," or sets of interleaved next-adjacent axial modes, that can oscillate separately or simultaneously in theN = 2case.     

Optical-Kerr-enhanced mode locking of a lamp-pumped Nd:YAG laser

We discuss the potential use of three new mode-locking techniques, namely additive-pulse mode locking, the combination of self-phase modulation and group velocity dispersion, and Kerr lens mode locking, as simple retrofits to enhance the performance of conventional multi-watt lamp-pumped Nd:YAG lasers. Of the three, we discard the APM technique because of structural and power-handling difficulties. We then discuss theoretically and confirm experimentally that the combination of SPM plus gain dispersion can lead to pulsewidth reduction by a factor of 2 to 2.5 but not more, in agreement with the analysis of Haus and Silberberg. Finally, while KLM can be very effective as a fast saturable absorber in many types of lasers, we find that its application to lamp-pumped YAG lasers is frustrated by instabilities in thermal focusing and transverse mode position characteristic of this type of laser     

Diode-pumped, frequency-stable, tunable, continuous-wave Nd:glasslaser

Stable operation of a diode-laser-pumped CW Nd:glass laser with an external resonator, including frequency tuning and line narrowing elements, is reported. The laser operated successfully on a single frequency, was tunable over more than 3 THz, and showed potential for frequency stabilization to kHz or better with a simple servo loop. The requirements for such a loop were determined, and it was found that a bandwidth less than 10 kHz could stabilize the device     

Activ-Passive mode locking of an Nd:phosphate glass laser pusing #5 saturable dye

An acoustooptic loss modulator and Eastman #5 saturable absorbing dye are used to stably mode lock a TEM00Nd:phosphate glass oscillator. This hybrid approach has enabled reliable generation of ∼ 6 ps duration pulses largely free of occurrences of satellite pulse structure.     

GaAs对脉冲Nd:YAG激光器的调Q和锁模

本文分析半导体材料GaAs对1064nm激光的可饱和吸收特性,在闪光灯抽运的平凹腔和平凸腔Nd:YAG激光器中,插入GaAs样品作为调Q器件,实现了激光器的被动调Q运转,分别获得脉冲宽度32.7ns(平凹腔)和30.9ns(平凸腔)的激光脉冲。实验上研究了平凹腔腔长和输出镜透过率对调Q激光输出性能的影响。当平凹腔腔长增加到125cm时,观察到GaAs对1064nm激光的被动锁模。对上述实验结果给予了合理的理论解释。     

FM and AM mode locking of the homogeneous laser--Part II: Experimental results in a Nd:YAG laser with internal FM modulation

In Part I of this paper [1], a theoretical analysis of the mode-locked homogeneous laser was given. In this part we present experimental results for the Nd:YAG laser with internal phase modulation. LiNbO3was used as the modulator crystal, and a method to measure the single-pass phase retardation of the modulator accurately at 1.06 μ is described in detail. The pulsewidth and spectral width of the mode-locked laser were measured as a function of depth of modulation, and good agreement with theory was obtained. Etalon effects in the laser were observed, and the results agreed very well with the theory. Mode-locked spectral bandwidths of up to 16 GHz, implying mode-locked pulses as short as 40 ps, were obtained.     

Experimental and theoretical studies on colliding pulse mode locking

Experimental and theoretical studies on colliding-pulse mode locking (CPM) are presented. The equations of the theoretical model take into account all the orders in pulse energies and the results are calculated numerically. It is shown that the CPM laser has an asymmetric pulse shape which can be approximately expressed in terms of the "asymmetric hyperbolic secant" function,[exp (-t/T_{1}) + exp (t/T_{2})]^{-2} (T_{1} < T_{2}). The experimental results on the pulse shape and pulse width of the CPM ring dye laser are compared to the numerical ones.     

Fundamental and third-order harmonic modelocking of an Er:Yb:glasslaser

Fundamental harmonic modelocking operation at 2.5 GHz of an Er:Yb:glass laser by an LiNbO₃ phase modulator has been achieved in a compact resonator configuration. A comparison with third-order harmonic modelocking of the same laser in a folded cavity is presented     

Active mode locking of lasers using an electrooptic deflector

The deflector shows excellent loss modulation characteristics in a laser cavity under large signal operation. The mode locker is capable of generating very short optical pulses comparable to those obtained by passive mode locking. In experiments, an LiTaO₃ double-prism deflector is used as the mode locker for an Nd:glass laser. As a result, stable 6-ps pulses are obtained     

LiF：F￣－＿2色心晶体对连续Nd：YAG激光器锁模特性的研究

实验研究了ＬｉＦ：色心晶体对ＣＷＮｄ：ＹＡＧ激光器的锁模特性，获得了连续稳定的锁模脉冲序列输出。     

Passive mode locking of an energy transfer continuous-wave dye laser

The first passive mode locking of a continuous-wave energy transfer dye laser is reported. Using an argon ion laser-pumped mixture of rhodamine 6G and sulphur rhodamine 101 as the active medium, pulses of less than 500 fs duration have been generated over the spectral range 652-694 nm using two different saturable absorbers in a simple linear cavity without dispersion optimization. Pulses as short as 120 fs have been measured using standard second-harmonic generation autocorrelation techniques.     

Passive mode locking in a diode-pumped Nd:GdVO/sub 4/ laser with a semiconductor saturable absorber mirror

We demonstrate Q-switched and CW passive mode locking in a laser-diode-pumped Nd:GdVO/sub 4/ laser with a semiconductor saturable absorber mirror. The repetition rate of the Q-switched envelope increased from 23.1 to 260 kHz as the pump power increased from 1.75 to 13.0 W. At a pump power of 13.7 W, the Q-switched mode locking changed to CW mode locking. The maximum average output power of 4.9 W with a 140-MHz repetition rate was obtained at a pump power of 17.9 W and the single mode-locked pulse energy was 0.035 /spl mu/J. The CW mode-locked pulse duration was measured to be /spl sim/11.5 ps.     

Experimental study of thermal lensing of Nd：YAG laser

Beamfocusing and higher-order wavefront distortiondue to heat dissipationinalaser gain mediumarei mpor-tant considerationsinthe design of solid-statelasers be-cause wavefront distortion can profoundly influence theperformance of a givenlaser design.Althou…     

Experimental study of thermal lensing of Nd：YAG laser

Beamfocusing and higher-order wavefront distortiondue to heat dissipationinalaser gain mediumarei mpor-tant considerationsinthe design of solid-statelasers be-cause wavefront distortion can profoundly influence theperformance of a givenlaser design.Althou…     

Feedback to maintain injection locking of Nd:YAG lasers

It has been previously shown that stable, narrowband operation of Nd :YAG lasers can be achieved by injection seeding, provided the detuning between the slave and injection lasers is sufficiently small. We have found a new simple method of monitoring this detuning which can be used to maintain stable operation for hours at a time.     

Multiple mode locking of lasers

Details of experimental results on higher order phase-locking phenomena of a He-Ne laser with a fixed cavity length and a fixed position of the laser tube in the cavity are presented. Two methods have been used in the experiments in order to obtain high bit-rate optical pulses. In one method modified Michelson-type resonators and a three-mirror Fabry-Perot resonator are utilized to suppress the oscillation of the undesired modes. Optical pulses of repetition rates up to about 600 megabits/s have been obtained. The second method utilizes an internal phase perturbation in a conventional Fabry-Perot cavity at a frequency nearly equal to a multiple of the longitudinal mode spacing. The repetition rate of optical pulses generated does not always coincide with the modulation frequency, but depends on the fine tuning of the frequency. In contrast to the former method, mode quenching is not necessarily required to produce multiple-bit pulses.     

1 ns脉宽激光Nd:YAG双通放大的实验研究

对纳秒脉宽激光进行了双通放大的实验研究。主振荡器输出的单脉冲能量为0.16mJ、重复频率为5 Hz,光束质量M2为1.5和脉冲宽度为0.964ns的种子激光,经过掺杂浓度为1.0at%,3mm×120mm的Nd:YAG双通放大器放大后,得到了单脉冲能量为88mJ、脉宽为0.972ns、M2为1.7和不稳定度小于±3%的双通放大激光输出。