倾斜结构InGaAsP/InP集成超辐射光源

为提高半导体超辐射器件的输出功率 ,在原有的将超辐射发光管 (SLD)与半导体光放大器 (SOA)单片集成的基础上 ,将器件电流注入区中心轴线倾斜 6° ,制得了 1 5 μm倾斜结构的InGaAsP InP集成超辐射光源。发现这种新型结构的单片集成器件具有抑制激射的功能。在较低的电流注入下 ,得到了 38mW的脉冲超辐射输出功率。其光谱宽度 (FWHM )和平行、垂直于结平面的远场半宽分别为 16nm ,15°和 6 4°。同时 ,通过对该集成器件特性的研究 ,发现如何增加SOA部分的入射光功率是提高该集成器件性能的一个十分关键的因素     

非均匀阱宽多量子阱1.55 μm高功率超辐射光源

采用非均匀阱宽多量子阱材料拓宽超辐射器件的输出光谱 ,并利用前期关于倾斜脊形集成超辐射光源的研究成果 ,制得了新型的 1 5 5 μm高功率宽光谱InGaAsP InP集成超辐射光源。发现该器件较均匀阱宽多量子阱器件的输出光谱有很大变化 ,光谱半宽由原来的 2 0～ 30nm ,增加到 4 5～ 6 0nm左右。该器件同样具有较好的抑制激射能力 ,在可测试范围内 ,在没有蒸镀腔面抗反射膜的情况下未见激射模式的出现。在准连续工作条件下 ,器件最大峰值功率已达到 15 0mW以上。     

970 nm超辐射发光二极管弯曲脊形波导数值分析

本文基于光束传播法(beam propagation method, BPM)和时域有限差分法(finite difference time domain method, FDTD)建立了分析模型,模拟并分析了弯曲脊形波导超辐射发光二极管(superluminescent light emitting diode, SLD)不同结构参数(刻蚀深度、曲率半径、脊形宽度)对波导损耗的影响和倾斜脊形波导不同结构参数(刻蚀深度、脊形宽度、倾斜角度、发射波长)对模式反射率的影响。计算表明,弯曲脊形波导的刻蚀深度和曲率半径是影响波导损耗的重要因素。刻蚀深度较浅使波导对光场的限制作用较弱,过小的曲率半径会使模式传输泄露严重,损耗大大增加。脊形宽度越大,波导损耗越小,其对波导损耗影响较小。脊形波导的端面倾斜角度是抑制模式反射率的重要因素,脊形宽度增加,模式反射率逐渐减小,并在特定的几个角度形成的奇点达到最小值。刻蚀深度对于模式反射率的影响作用较小,但随着刻蚀深度的增加,奇点发生的角度产生了向小角度偏移。在特定的倾斜角度范围内,随着波长减小,奇点的数目会逐渐增加。研究结果可对设计具有优越性能的SLD器件...     

共腔双稳态半导体激光器的实验研究

本文对SiO_2掩蔽隔离的脊形波导条形结构 InGaAsP/InP DH双稳态激光器进行了研究,这种器件具有内部Q开关特性.对其稳态L-1特性,阈值电流与温度的关系,激射光谱与温度的关系及在激射情况下的光谱特性进行了测量,得到了初步的结果.     

双波长半导体激光器Y形耦合波导模拟研究

提出了一种双DBR半导体激光器结构,该结构包括布拉格光栅、脊形波导、Y形波导、锥形放大器等部分,目标是实现半导体激光器双波长高功率、高光束质量的近红外激射.本文使用Rsoft BeamPROP模拟分析了Y形耦合波导的分叉角度对光传输的影响,确保双DBR脊形波导发射出的单模激光不互相干涉,使双波长单模激光在其中传输损耗最小.     

同一外延层结构高速DFB激光器/EA调制器集成光源的研究

对利用同一外延层结构实现DFB激光器与EA调制器的集成机理进行了理论分析,指出该集成方法有可能获得激光器激射波长与调制器工作波长之间的良好匹配.在理论分析的基础上,研制出了基于同一外延层结构的高速集成光源,该器件具有良好的静态特性,并达到了约8GHz的小信号调制带宽.     

同一外延层结构高速DFB激光器/EA调制器集成光源的研究

对利用同一外延层结构实现ＤＦＢ激光器与ＥＡ调制器的集成机理进行了理论分析,指出该集成方法有可能获得激光器激射波长与调制器工作波长之间的良好匹配．在理论分析的基础上,研制出了基于同一外延层结构的高速集成光源,该器件具有良好的静态特性,并达到了约８ＧＨｚ的小信号调制带宽．     

长波长超辐射集成光源

为适应光谱分割技术的需求,我们采用ＩｎＧａＡｓＰ／ＩｎＰ单量子阱外延片,用直接耦合的方法将超辐射发光管与半导体光放大器单片集成,制得了１．３μｍ长波长超辐射集成光源,取得了初步的实验结果,验证了这种长波长集成器件的可行性。脉冲输出功率与长波长超辐射发光管相比有很大提高。半导体光放大器的增益达到１９ｄＢ。     

双光子染料ps激光泵浦下的超辐射和腔激射

本文首次报道了ps激光脉冲泵浦下的有机染料的上转换腔激射，当用1064nm激光（40ps）激发有机染料PSPS[trans-4-（4′-pyrrolidinyl styryl)-N-methyl pyridinium methyl sulfate]时，可以得到中心波长分别为615nm和620nm的超辐射和腔激射，用再吸收现象解释了腔激射相对超辐射的红移现象，用不同条件下再吸收系数的不同解释了超辐射和腔激射相对双光子荧光的蓝移。该染料的399ps的荧光寿命有利于腔激射的产生。我们得到了远大于泵浦光脉冲宽厚的200ps激光振荡，并对此现象进行了解释。     

InGaAsP/InP超辐射集成光源

为提高半导体超辐射器件的输出功率 ,采用直接耦合的方法 ,将超辐射发光管 (SL D)与半导体光放大器 (SOA)单片集成 ,制得了 1.3μm超辐射集成光源 ,其脉冲输出功率为 50 m W,光谱宽度 (FWHM)为 2 8.9nm。通过对放大器增益特性的讨论 ,得出了既能稳定器件性能 ,又可以提高输出功率的有效工作方案。     

Output characteristics of diode pumped fiber ASE sources

High power amplified spontaneous emission (ASE) from multicore Nd:fibers pumped by laser diode arrays is investigated experimentally and theoretically. Particular examination is made of threshold conditions at which lasing occurs. A model is presented which describes output power for arbitrary end reflectors. Experimental measurements of lasing threshold reflectivity versus pump power are made and are shown to deviate from the usual laser threshold condition at high pump powers. It is demonstrated that feedback from Rayleigh backscattering can be sufficient to drive the ASE source above lasing threshold in certain configurations     

The onset of coherence collapse in DBR lasers

A study of the dependence of the onset of coherence collapse on laser output power is discussed. Three-section multiquantum-well-distributed-Bragg-reflector (MQW-DBR) lasers were used. The fraction of light reflected back into the lasing mode was varied, and the point at which the transition to coherence collapse occurred was measured. This feedback level varies approximately linearly with laser output power. For these lasers, when the output power is 1 mW, the transition to coherence collapse begins when the optical feedback into the lasing mode is below -40 dBm; when the feedback power is -35 dBm, the laser line is completely collapsed     

Neodymium-doped silica-based planar waveguide lasers

Fabrication and lasing characteristics of Nd-doped P₂O ₅-SiO₂ core planar waveguide lasers are described. CW oscillation at a wavelength of 1052.5 nm was successfully demonstrated in 0.2 wt%-Nd-doped silica-based planar waveguides fabricated on a silicon substrate by flame hydrolysis deposition and reactive ion etching. The lasing threshold and slope efficiency were optimized in an 8-μm-wide waveguide, in which a lasing threshold pump power of 26 mW and a slope efficiency of 2.0% were obtained for 805-nm pumping. The measured lasing characteristics agreed with theoretical characteristics calculated by employing finite-element waveguide analysis, indicating that the waveguide structure was well controlled by the developed waveguide fabrication technique. The possible lasing characteristics of the waveguide lasers are discussed based on this agreement. The attenuation and emission properties of the waveguides are also described     

Tunable dual-wavelength-switching fiber grating laser

We report a tunable dual-wavelength-switching fiber grating laser by exploiting the large homogeneous gain broadening in erbium (Er)-doped fiber to suppress simultaneous lasing. Wavelength switching was accomplished through a novel design which has two overlapping cavities sharing a single-gain medium. The loss corresponding to one of the lasing wavelengths can be modulated via an optical chopper. Output power of about 6 mW and extinction ratio up to 50 dB were observed. The lasing wavelengths were tunable and switching was demonstrated for wavelength separations ranging from 0.35 to 23.5 nm     

基于光纤拉锥及相位调制的可切换多波长掺铒光纤激光器

研究了一种全光纤可切换多波长掺铒光纤激光器。该激光器利用一段缠绕在压电陶瓷上的单模光纤作为正弦相位调制器以及基于光纤拉锥的马赫-曾德尔干涉仪作为梳状滤波器,抑制由于掺铒光纤的均匀展宽效应引起的模式竞争,从而避免了在室温下不稳定的单波长激射,实现了多波长掺铒光纤激光器的稳定输出。实验中观察到稳定的5个波长的同时激射,相邻波长间隔为0.804 nm。信噪比大于40 dB,3 dB带宽约为0.023 nm,中心5个波长输出功率的平坦度为14 dB。同时,激光器具有灵活的波长可切换特性,通过调整驱动信号和偏振控制器的状态,实现了单波长、双波长、三波长以及更多波长的输出。该激光器可应用于大容量波分复用系统和光纤传感。     

Gain-clamped erbium-doped fiber-ring lasing amplifier with low noise figure by using an interleaver

A novel all-optical gain-clamped erbium-doped fiber-ring lasing amplifier (GC-EDFRLA) has been demonstrated, in which the odd port of a 100/200-G interleaver was used to form a fiber-ring cavity to produce lasing oscillation for locking the gain and its even port was employed to export the amplified signals. In such a way, the problem existing in the conventional GC-EDFRLA is solved. The signal can be exported separately without the lasing power while the noise figure (NF) is very low. Finally, the GC-EDFRLA with a low NF of 4.2 dB was achieved.     

掺铒光纤环形激光器输出波长的研究

为了得到掺铒光纤环形激光器的激光运行波长与掺铒光纤长度和耦合比之间对应关系,基于3能级的速率方程采用解析方法进行了理论分析,并通过实验给予验证,分别取得了激光运行波长随掺铒光纤长度和耦合器耦合比变化的数据。结果表明,随着光纤长度的增加,激光的输出波长往长波方向移动,输出波长为1563nm 时输出功率最大,掺铒光纤最佳长度大约为11.5m,耦合比越大,激光的输出波长越短。这一结果对改变耦合比进行光纤激光器激光波长调谐的设计有很大帮助。     

A Taper-Fused Microspherical Laser Source

We report on the realization of an integrated lasing device consisting of a microsphere optical resonator fused to a tapered optical fiber. A microsphere fabricated from Er: Yb-codoped phosphate glass is heated above its glass transition temperature of 375degC by pumping it at 977 nm with 70 mW via a tapered optical fiber. The onset of thermal stress in the glass at a maximum pumping power results in the sphere melting and fusing to the taper coupler, without inhibition of whispering gallery mode lasing. A taper-fused microsphere laser with ~4.5 muW of lasing power at 1593 nm is demonstrated.     

Multiwavelength lasers based on semiconductor optical amplifiers

Stable multiwavelength lasing is demonstrated with a novel laser, in which a semiconductor optical amplifier offers optical gain and cascaded sampled fiber gratings serve as a comb filter. Five lasing lines are obtained with a fixed wavelength spacing of 0.8 nm. Optical power fluctuations among the lasing lines are improved by adjusting the reflectivity profile through the cascade of two sampled gratings     

Excited-State-Mediated Capture of Carriers Into the Ground State and the Saturation of Optical Power in Quantum-Dot Lasers

Excited-state-mediated capture of carriers from the waveguide into the lasing ground-state in quantum dots (QDs) is studied. Such a two-step capture places a fundamental limitation on ground-state lasing-the output power saturates at high injection currents. The saturation power is controlled by the transition time between the excited- and ground-state in a QD. The longest, cut-off transition time exists, beyond which no ground-state lasing is possible