Effect of Si-nc to ${hbox {Er}}^{3+}$ Coupling Ratio in EDWAs Longitudinally Pumped by Visible Broad-Area Lasers

We present a finite element based model for Si-nc sensitized ${hbox {Er}}^{3+}$ doped waveguide amplifiers (EDWA), longitudinally pumped by a novel pumping scheme using broad-area visible lasers, which accurately describes the effect of the Si-nc to ${hbox {Er}}^{3+}$ coupling ratio on the amplifier performance.      

Er–Yb共掺磷酸盐波导激光器中的Er–Yb能量传递研究

对Er–Yb共掺磷酸盐玻璃波导激光器进行理论研究,弄清Er-Yb能量传递的作用。利用重叠积分方法,对Er-Yb共掺系统的速率方程及激光器中信号光和泵浦光的传输方程进行求解,在980-nm的泵浦光作用下对光波导激光器中Er-Yb能量传递过程的影响做了详细研究,讨论了Yb-Er能量传递对激光器的增益和输出特性的影响。计算结果表明：Yb-Er能量传递对激光器的增益和输出功率的影响不明显。Yb3+离子在Er3+-Yb3+共掺系统中起化解Er3+离子“团簇”、提高泵浦效率的作用。     

High-power operation of aluminum-free (κ=0.98 μm) pumplaser for erbium-doped fiber amplifier

The authors discuss the fabrication and characteristics of high-power (P_CW=430 mW) InGaAs/InGaAsP/InGaP ridge waveguide lasers emitting at λ=0.98 μm, which is the optimum wavelength for pumping erbium-doped fiber amplifiers. In the past, high-power operation of Al-free pump lasers has been limited to 150 mW because of catastrophic optical damage of the mirror facet. This problem has been largely removed by increasing the spot size of the laser with the aid of an improved waveguide design. As a result, Al-free lasers can now achieve a maximum power comparable to the conventional GaAlAs-based pump lasers for λ=0.98 μm     

Polarisation-insensitive 980/1550 nm wavelength (de)multiplexerusing MMI couplers

A polarisation-insensitive planar 980/1550 nm wavelength (de)multiplexing coupler based on multimode interference (MMI) effects is presented. The device is useful for integration with rare-earth doped waveguide amplifiers and lasers. The waveguide parameters and, in particular, the coupler width are chosen to optimise the device performance and obtain polarisation-insensitivity     

Tm3+/ Ho3+离子掺杂中红外超快激光技术研究进展（特邀）

稀土离子Tm3+/ Ho3+ 掺杂中红外2 μm波段超快激光由于广泛的应用前景成为近十余年来激光领域的研究热点之一。文中首先综述了稀土离子Tm3+/Ho3+掺杂固体/光纤2 μm波段超快激光锁模技术进展,包括主动锁模技术以及饱和吸收、克尔透镜、非线性偏振旋转、非线性光环形镜、非线性多模干涉等被动锁模技术;其次,结合激光增益介质及色散管理技术回顾了Tm3+/ Ho3+掺杂固体和光纤锁模激光脉冲宽度压缩进展;再次,总结了Tm3+/ Ho3+大能量/高功率超快激光技术及进展;最后,对2 μm波段超快激光发展趋势进行了总结和展望。     

5.6-W Broad-Area Lasers With a Vertical Far-Field Angle of 31$^{circ}$ Emitting at 670 nm

Highly efficient 670-nm high-power broad-area laser diodes with a single InGaP quantum-well embedded in AlGaInP waveguide layers and n-AlInP and p-AlGaAs cladding layers are presented. The developed vertical layer structure leads to a vertical far-field angle of 31deg. At 15degC, 100 mu-m-wide broad-area lasers reach an output power of 5.6 W limited by thermal rollover. The conversion efficiency was 41% at 1.5 W. A 7600-h reliable operation at 1.5 W and a mean time to failure of about 37550 h will be reported.     

Six-Port Interferometric Technique for Accurate $W$ -Band Phase-Noise Measurements

An innovative six-port (SP) phase-noise measurement technique for millimeter-wave high-power sources is proposed in this paper. Simulation results using a 94-GHz rectangular waveguide SP circuit model validates the measurement principle for both millimeter-wave oscillators and amplifiers. Phase-noise measurement results of a 100-W extended interaction Klystron amplifier are presented and discussed. Compared to conventional methods, this new method allows accurate low-cost phase-noise measurements.     

Ultrashort-Pulse High-Power Yb3+-Doped Fiber Amplifiers

Ultrashort optical pulse propagation in high-power Yb³⁺-doped fiber amplifiers (YDFA) is studied using a spectrally resolved nonlinear power equation for the coupled pulse components. The Yb³⁺ ions transitions are modeled using a rate equation. Examples for high-power YDFAs with normal dispersion show good qualitative agreement with experimental results. We analyze the effects of the incident pulse wavelength, pulse peak power, Yb³⁺ concentration, pump filling factor, fiber length, pumping configuration, pump power and nonlinear index, on the intensity distribution of short amplified pulses. We also demonstrate the spectral compression of an initially negative-chirped pulse.     

Theoretical analysis of lateral modes in broad-area semiconductorlasers with profiled reflectivity output facets

This paper provides a theoretical analysis of the near-threshold behavior of broad-area lasers with profiled reflectivity output facets. Threshold currents and far-field patterns of the lateral modes are calculated according to two models. The first model assumes that the modes are determined by the effective lateral waveguide, while the second one is based on the modes of an open resonator. Single- and three-stripe mirror configurations have been considered. The main goal of the analysis is to identify the lateral guiding mechanism in such lasers and to assess the influence of the mirror configuration on thresholds for single- and multimode operation and on beam characteristics     

Improved gain characteristics in high-concentrationEr3+/Yb3+ codoped glass waveguide amplifiers

High-concentration Er³⁺/Yb³⁺ codoped glass waveguide amplifiers are analyzed by means of a finite-element-based code. Efficient Yb³⁺ to Er³⁺ energy transfer is shown to be a useful mechanism to reduce performance degradation due to Er³⁺ ion-ion interactions. Numerical calculations based on realistic waveguide parameters demonstrate the possibility of achieving high gain with a short device length     

980 nm diode laser for pumping Er3+-doped fiberamplifiers

A high-power 980-nm diode laser, whose performance satisfies the requirements for pumping Er³⁺-doped optical fiber amplifiers, is described. The device is grown by atmospheric pressure organometallic vapor-phase epitaxy and contains a strained, step-graded In_0.25 Ga_0.75As/AlGaAs single-quantum-well active region. The threshold current of the ridge-waveguide laser is 8 mA, and a CW power output of 125 mW with a different quantum efficiency of 59% is demonstrated     

Low-threshold current density InGaAsP/InP injection lasers with three-layer-waveguide double heterostructure (jth?0.5 kA/cm2 at 300 K)

Double heterostructure InGaAsP/InP lasers with a three-layer waveguide (or `separate-confinement? DH) have been prepared by the LPE method with a thin active layer. A decrease in threshold current density has been observed up to 512 A/cm2 in a four-sided cleaved diode at room temperature. CW operation of broad-area diodes is obtained in the pumping current range up to 2.5 A. Calculations of threshold current density for these laser structures are presented.     

Stable operation (over 5000 h) of high-power 0.98-μm InGaAs-GaAsstrained quantum well ridge waveguide lasers for pumpingEr3+-doped fiber amplifiers

A maximum output power of 115 mW and a slope efficiency of 0.92 W/A have been achieved in 0.98-μm InGaAs strained quantum well lasers with a 3-μm-wide ridge waveguide structure for efficient fiber coupling. Stable operation of over 5000 h under 50°C constant power operation with an optical power density of 3.9 MW/cm² has been demonstrated with a degradation rate as low as 5×10^-6 per hour. These results show that this device is promising as a practical pumping source for Er³⁺-doped fiber optical amplifiers     

Measurement of spatial modes of broad-area diode lasers with 1-GHz resolution grating spectrometer

A 1-GHz resolution double-pass grating spectroscopy of broad-area diode lasers is performed. Measurements of spatial and spectral distribution of emitting power are performed as a function of pumping current. Results are confronted with the mode structure of gain-guided waveguide. Nonlinear coupling of lateral modes has been observed and quantified.     

对平板耦合半导体激光器的探索

To obtain a high-power and efficient single-mode laser, a new laser called the slab coupled optical waveguide laser （SCOWL） has been developed. We have simulated its structure and grown the chip with this structure by low-pressure metal organic chemical vapor deposition. We have also produced the broad-area SCOWL and compared it with the traditional structure laser in terms of some performances. This work lays the foundation for further research of ridged lasers with the same structure.     

Littman光栅外腔可调谐Yb3+双包层光纤激光器

本文对LD泵浦的光栅外腔可调谐双包层Yb3 光纤激光器进行了实验研究．采用Littman外腔结构，研究了Yb3 光纤激光器的调谐特性．输出激光调谐范围42nm，谱线宽度0．08nm，最大输出功率达到了460mW，斜率效率约30％．并对其输出光功率随波长的变化进行了观测和分析．     

CO2激光熔接型双包层光纤侧面抽运耦合器

为了把高功率的半导体激光器抽运光耦合入直径只有数百微米的双包层光纤内包层,以获得高的抽运功率,同时简化端面抛磨式熔接型侧面耦合器复杂的光纤处理工艺,提出了一种基于CO2激光熔接的双包层光纤侧面抽运耦合器的新方法,并进行了实验验证,介绍了试验装置和制作过程,制作了内包层直径为125μm非掺杂双包层光纤与105μm/125μm多模光纤的侧面耦合器,得到了82%的耦合效率测试结果。结果表明,所研制的熔接型侧面耦合器在侧面抽运的高功率双包层光纤激光器中具有很好的应用前景。     

30 Gb/s Over 100-m MMFs Using 1.1-$mu$ m Range VCSELs and Photodiodes

We developed 1.1-mum-range vertical-cavity surface-emitting lasers based on InGaAs-GaAs quantum wells, back-illuminated InGaAs photodiodes, and transimpedance amplifiers (InP heterojunction bipolar transistor) for high-speed optical interconnection. Clear eye opening operation and error-free transmission at 30 Gb/s over 100-m multimode fibers (GI32) were successfully achieved for the first time.     

High-power laser diodes of wavelength 808 nm based on various types of asymmetric heterostructures with an ultrawide waveguide

The parameters of high-power multimode laser diodes featuring a radiation wavelength of 808 nm obtained on the basis of asymmetric heterostructures with an ultrawide waveguide in the systems of AlGaAs/GaAs and (Al)GaInP/GaInAsP/GaAs are compared. In the lasers based on an AlGaAs/GaAs system, the maximum optical power was limited by optical degradation of the SiO₂/Si mirrors and amounted to 4.7 W. In the lasers based on an (Al)GaInP/GaInAsP/GaAs system, the maximum optical power was limited by thermal saturation and equaled 7 W. The obtained results show that the (Al)GaInP/GaInAsP/GaAs system is more reliable from the standpoint of an increase in both the maximum optical power and operation life of lasers.