An analytical study of a periodically driven laser with a saturable absorber

We consider the rate equations for a laser with an intracavity saturable absorber and subject to a periodically modulated pump. By deriving simplified equations for a map valid for strongly pulsating regimes, analytical conditions are determined that specify the properties of both frequency-locked and unlocked behaviors. As the strength of the modulation is increased, quasiperiodic and period-doubling bifurcations are predicted. However, only the transition from locking to non-locking through a quasiperiodic bifurcation is possible for realistic values of the parameters. Our results are consistent with previous numerical and experimental studies of modulated lasers with a saturable absorber. Received 10 March 2001     

High repetition rate passively Q-switched diode-pumped Nd:YVO4 laser

We demonstrated an efficient and compact, diode-pumped passively Q-switched Nd:YVO₄ laser operation at 1.064 μm wavelength with high repetition rate, using Cr⁴⁺:YAG as saturable absorber, formed with a simple flat–flat resonator. The maximum CW output power of 4.05 W was obtained at the incident pump power of 8 W. For Q-switched operation, the maximum average output power was measured to be 1.4 W with the corresponding repetition rate of 200 kHz, the pulse width of 60 ns when the initial transmission of Cr⁴⁺:YAG crystal was 85%. The shortest pulse width of 12 ns, the largest pulse energy of 36 μJ and the highest peak power of 3 kW were obtained when the Cr⁴⁺:YAG crystal with an initial transmission of 60% was used.     

考虑激光下能级弛豫过程的调Q Nd∶YAG速率方程理论分析

本文比较了考虑与不考虑激光下能级弛豫过程的两种形式的调Q速率方程,并以二极管激光侧面泵浦电光调QNd∶YAG为例,分别采用两种形式的调Q速率方程,分析了调Q过程中上、下能级粒子数变化过程,计算了输出调Q激光脉冲波形、峰值功率以及能量,进行了比较分析,并解释了调Q“子脉冲”与拖尾现象     

Diode array pumped, non-linear mirror Q-switched and mode-locked Nd : YVO4 laser — a good tool for powder SHG measurement

A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO₄ laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while operating in QML regime is much higher but pulses suffers from poor amplitude stability. The incorporation of an acousto-optic modulator as an active Q-switch enhances the stability of the QML pulse envelope. The second-order non-linearity of powdered crystalline urea is conclusively measured with respect to KDP while the laser is operating in passively Q-switched and passively mode-locked regime as well as in actively Q-switched and passively mode-locked regime.     

激光二极管列阵侧面泵浦Nd：YLF激光器

报道准连续６０Ｗ激光二极管列阵侧面泵浦Ｎｄ：ＹＬＦ固体激光器的研究结果，当器件的动转重复频率为３０Ｈｚ时，得到４．４ｍＪ的１．０４７μｍ激光输出，光－光转换效率达到１８．３％，斜率效率达２４．４％。声光和电光调Ｑ，得到能量为２．２ｍＪ，脉宽分别为５０ｎｓ和３０ｎｓ的脉冲输出。     

Passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror

A passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror (SESAM) is demonstrated. Q-switching is observed with the output power produced at a slope efficiency of 29.4% with respect to the absorbed pump power. The maximum average output power of 8.37 mW is achieved. The pulse repetition frequency obtained can be turned from 1.72 to 7.95 kHz. The pulse energy of 17.2 nJ has been obtained at the pump power of 46.75 mW, and the pulse width is 30 μs.     

Passively Q-switched erbium-doped fiber laser based on gold nanorods

We have demonstrated that the gold nanorods (GNRs) can be used as effective saturable absorbers for passively Q-switched erbium-doped fiber laser (EDFL). Two types of GNRs were synthesized by a seed-mediated growth method. The longitudinal surface plasmon resonance wavelengths of the GNRs with different aspect ratios were around 1068 and 1442 nm, respectively. The GNRs were mixed with sodium carboxymethylcellulose (NaCMC) to form GNRs-NaCMC films with different absorption wavelengths. Using these GNRs-NaCMC films, 9.6-μs pulses with a repetition rate of ∼22.9 kHz and 10.4-μs pulses with a repetition rate of ∼22.4 kHz were obtained from the passively Q-switched EDFLs at a pump power of ∼120 mW, respectively.     

基于金纳米棒可饱和吸收体的被动调Q掺铒光纤激光器

利用种子诱导生长法制备了长径比为5的金纳米棒,测量了它的吸收谱,结果表明该纳米棒具有较宽的吸收带（800~1 600 nm）。进一步测量了它的非线性吸收性质,结果表明它在1.56 μm波长处具有可饱和吸收特性,有望被用于实现被动调Q脉冲激光的输出。将该可饱和吸收体置于掺铒光纤激光器腔内,当泵浦功率增至30 mW时开始有稳定的调Q脉冲激光输出,输出激光的工作波长为1.56 μm。当泵浦功率为205 mW时,可获得的最大输出功率约6.9 mW,脉冲能量达219 nJ。研究结果表明,这种新型可饱和吸收体在脉冲激光领域具有广阔的应用前景。     

High conversion efficiency,high power density Q-switched fiber laser

An acoustic-optic Q-switched all-fiber laser With a high-repetition-rate, a short pulse width, a wide spectrum, and a high conversion efficiency is experimentally demonstrated. In the laser configuration, a （1＋1）x 1 side-pumping coupler is introduced to perform backward pumping, and a 10/130%tm Yb fiber is adopted. The acoustic-optic component operates in the first direction, achieving a Q-switched pulse with a repetition rate adjustable in the range of 20 kHz-80 kHz. Under a repetition rate of 20 kHz and a pump power of 6.76 W, the fiber laser obtains a highly efficient and stable pulse output, with an average power of 4.3 W, a pulse width of 56 ns, a peak power of 3.83 kW, and a power density of 1.39x 101~ W/cm2. Particularly, the optic-optic conversion efficiency of the laser reaches as high as 64%. Another feature of the pulsed laser is that the high reflection mirror reflects the pump light as well, which brings the secondary absorption of the pump power into the gain fiber.     

利用受激布里渊散射Q开关的研究

本文报道受激布里渊散射Q开关,叙述了Q开关原理,实验研究了各种因素对输出特性的影响,并与染料Q开关作了比较.