1.3- mu m Nd:YAG crystal fiber amplifiers

Using unclad Nd:YAG crystal fibers of 10-40 mu m diameter and 1 cm long, and a laser diode pumping power of 83 mW at a wavelength of 0.81 mu m, gains of up to 6.5 dB at 1.32 mu m have been observed. No significant dependence of gain on signal polarization or output signal level between -43 and -5.4 dBm was observed for a 16 mu m diameter fiber. For smaller diameter fibers and a reduction of the competition from amplified spontaneous emission (ASE) at 1.064 mu m, much higher gains are expected. Extrapolation of experimental and theoretical results predicts gains in excess of approximately 30 dB for fiber diameters of 5 mu m.<>     

Interferometric measurement of low-frequency phase noise characteristics of diode laser-pumped Nd:YAG ring laser

Reports the interferometric measurement of the phase noise characteristics of a diode laser-pumped solid-state Nd:YAG 1.3 mu m laser based on a nonplanar ring cavity. Results show that the device has a low-frequency phase noise approximately three orders of magnitude lower than that observed with semiconductor diode lasers. The use of this source in fibre sensing applications is discussed.<>     

Cooling schemes for longitudinally diode laser-pumped Nd:YAG rods

Longitudinal diode laser pumping causes pronounced inhomogeneous heating of the laser material. The effect of the thermal load on the mechanical and optical properties is significantly influenced by the method used for cooling the pumped surface. Four methods for longitudinally pumped Nd:YAG rods were compared experimentally and with finite-element (FE) analysis. The pumped surface exposed to air or to flowing water, a sapphire plate pressed onto the pumped surface and composite rods, having an undoped pumped end, were investigated. The comparison includes temperature and stress distributions with the emphasis on thermal lensing. Careful validation of the FE code with experiments allowed to numerically comparing the cooling methods under identical conditions     

Single-frequency operation of an optically pumped monolithic Nd:YAG laser at 1.3 ?m

The design and of a monolithic Nd:YAG laser operating at 1.3 ?m is reported. The laser is pumped by a dye laser operating at 590 nm and exhibits a threshold pump power of 2.6 mW with a slope efficiency of 32%. The frequency stability is about 2 MHz and is limited by amplitude noise from the pumped laser.     

565 Mbit/s optical DPSK and PSK heterodyne transmission experiment using Nd:YAG lasers at 1.3 mu m

A 565 Mbit/s optical DPSK and PSK transmission experiment is described. Stable monolithic Nd:YAG ring lasers were used as light sources. A PSK demodulation scheme achieved a receiver sensitivity of -53.4 dBm and was found to be 1.3 dB better than DPSK.<>     

1.3 mu m semiconductor laser power amplifier

The performance of a 3.4-Gb/s system using a low-power 1.318- mu m distributed-feedback (DFB) laser transmitter and a traveling-wave semiconductor laser power amplifier is studied. The -14.5-dBm, input from a directly modulated DFB laser is boosted to +10.3 dBm, of which +4.8 dBm is coupled into the transmission fiber. The penalty, caused by amplifier noise and pattern effects due to gain saturation, is less than 0.5 dB.<>     

885nm抽运Nd∶YAG激光器

在二极管抽运Nd: YAG激光器中,量子亏损是影响晶体热积累的一个最重要参量,为了达到减少晶体热效应的目的,可采用直接抽运技术.经过理论分析,采用的二极管阵列中心波长为885nm、晶体尺寸为5.5mm×55mm,实验对比验证了多种透过率输出镜.结果表明,在透过率为58%时,获得最大单脉冲138mJ的静态输出,光光转换效率为12%.这一结果验证了采用885nm抽运源直接抽运技术的可行性,并有助于实验的进一步发展.     

High efficiency 1.3 mu m superluminescent diode with absorbing tapered waveguide

A new type of superluminescent diode (SLD) with a tapered waveguide in the absorbing region is proposed. This SLD structure monitors output power, as it emits monitor light from the rear facet that is about one-tenth the output power from the front one. Device parameters have been determined by beam propagation methods. A 1.3 mu m SLD fabricated by liquid phase epitaxy (LPE) with an absorbing waveguide 200 mu m long and with a 6.5 degrees tapered angle can emit output power of 13.5 mW from the front facet at a 200 mA driving current without lasing.<>     

二极管象散光束端面泵浦Nd:YAG激光器

研究了用象散二极管激光光束端面泵浦的TEM0m,TEMn0多模Nd:YAG激光器。文中报导了不同泵浦功率下的激光模式情况和稳定性情况,最大CW输出功率320mW,斜效率28%,最高稳定CW输出功率232mW,斜效率20%,为进一步研究二极管泵浦的列阵器件奠定了基础。     

GaAlAs／GaAs量子阱LD泵浦Nd：YAG激光器

利用分子束外延技术生长出了ＧａＡｌＡｓ／ＧａＡｓ折射率渐变分别限制单量阱材料。用该材料作出的激光二极管作泵浦源对Ｎｄ：ＹＡＧ激光器进行端面泵浦实验，在工作电流为３．３Ａ时，ＬＤ输出功率为２．７Ｗ，得到Ｎｄ：ＹＡＧ激光器的输出功率达７００ｍＷ，光－光转换效率达２０％。     

Stress tests on 1.3 ?m buried-heterostructure laser diode

Preliminary results of the accelerated aging test under stresses of temperature and current are presented. The degradation modes are found to be divided into two patterns which can be mapped in co-ordinates of these stresses.     

Spectroscopy and diode laser-pumped operation of Tm,Ho:YAG

Spectroscopic measurements and analysis of diode laser-pumped operation of Tm,Ho:YAG at 2.1 μm at room temperature have been performed. The peak effective stimulated emission cross section is measured to be 9×10^-21 cm² at 2.091 μm and the upper state lifetime is 8.5 ms. Under diode laser pumping, thresholds of 4.4 mW of absorbed power and slope efficiency of 19% have been demonstrated. Calculations of threshold power are performed based on the spectroscopic measurements. An energy transfer upconversion process is identified which leads to a sublinear rise in upper-state population with pump power     

LD侧面抽运全固态Nd:YAG紫外激光器的研究

为了使侧面抽运全固态355nm紫外激光器输出高质量光束的紫外激光,采用腔内光束传输矩阵模拟的方法,进行了谐振腔优化和腔内倍频和频结构设计。通过理论分析和实验验证,取得了输入电功率为280W、声光调制频率为40kHz时,355nm紫外激光的输出功率为10.58W、激光脉冲宽度20ns、光束质量因子M2=1.3的数据。结果表明,侧面抽运腔内倍频与和频可实现近基模高功率紫外激光的输出。这一结果对紫外激光器的工程化有一定指导意义。     

Plasma-hydrogenated low-threshold wide-band 1.3 mu m buried ridge structure laser

The plasma hydrogenation of p-type InP has been applied to the fabrication of buried ridge structure (BRS) lasers. The threshold current, output power and modulation bandwidth of the obtained devices compare favourably with those of more conventional ones fabricated by proton implantation on the same wafer.<>     

二极管泵浦的声光Q开关高重频Nd:YAG激光器研究

采用光纤耦合输出的连续激光二极管端面泵浦声光Q开关Nd:YAG激光器，在重复频率1kHz时，获得最窄脉宽5.5ns，最大峰值功率76kW；在重复频率20kHz时，最大平均功率4W（脉宽16ns），斜效率达33.4％。并对实验结果进行了讨论。     

同时锁模加调Q Nd：YAG激光器的研究

本文从理论上分析了均匀加宽Nd:YAG固体激光器的稳态锁模过程和同时锁模加调Q的原理。在谐振腔内插入声光锁模和调Q器件,实现了同时锁模加调Q运转,获得了最大峰值功率为84kW、脉宽为180ps的重复脉冲输出,使输出激光的峰值功率比单独锁模提高了10~3～10~4倍。     

Silicon Mach-Zehnder waveguide interferometers operating at 1.3 mu m

Mach-Zehnder waveguide interferometers have been fabricated in silicon and operation has been demonstrated at lambda =1.3 mu m. The switching mechanism is based on the thermally induced variation of the refractive index of crystalline silicon. Modulation depths of 40% were obtained for switching powers of 30 mW and switching times of 50 mu s.<>     

脉冲式Nd:YAG激光器克尔透镜锁模的研究

在平凹临界稳定腔脉冲式Nd:YAG激光器中插入LiF:F-2晶体实现稳定锁模运转。分析LiF:F-2非线性吸收在锁模过程中的作用,计算Nd:YAG自聚焦引起的腔的稳区范围和激光振荡模式的变化。理论和实验结果均表明,克尔透镜效应是实现该激光器锁模运转的关键因素。     

半导体泵浦被动调Q高重频Nd:YAG激光器

从被动调Q固体激光器的速率方程出发,分析给出了Cr4+:YAG被动Q开关Nd:YAG激光脉冲的峰值功率、脉冲能量、脉宽及重频等相关参量表达式.以此为基础,进行了光纤耦合输出的连续半导体激光纵向泵浦被动Q开关Nd:YAG激光器实验研究,采用不同参数Cr4+:YAG晶体作为被动Q开关,获得了不同参数的高重频脉冲激光输出.