光纤光栅外腔半导体激光器的理论和实验分析

从耦合模理论出发,结合激光原理,研究了光纤光栅外腔半导体激光器(FBG-ECL)的理论模型．得到光纤光栅反射率的解析解。利用速率方程理论讨论FBG-ECL的高频响应特性。根据等效腔模型．讨论了耦合系数对FBG-ECL阈值特性的影响。指出存在最佳光纤光栅反射率．使得激光器不仅功率输出大,而且边模抑制比高。最后实测了不同反射率情况下激光器的激射光谱。     

光纤光栅外腔半导体激光器特性的分析

研究了光纤光栅外腔半导体激光器(FBG-ECL)的理论模型;根据等效腔模型,讨论耦合系数对FBG-ECL阈值特性的影响,指出存在最佳光纤光栅反射率,使得激光器不仅功率输出大、而且边模抑制比高;利用等效腔长的手段,分析了腔长对光子寿命的影响,并结合速率方程讨论了FBG-ECL的高频响应特性;最后实测了不同反射率情况下激光器的激射光谱。     

大功率外腔半导体激光器的研究

介绍了一种用光栅作为外反馈元件，采用普通大功率半导体激光器管芯作为增益介质的方案。实验中实现了输出功率大于７０ｍＷ，边模抑制比大于３０ｄＢ。并对影响大功率外腔半导体激光器特性的参数进行了分析     

体布拉格光栅反射率对外腔半导体激光阵列输出光谱的影响

采用记录在光致热敏折射率玻璃中的反射型体布拉格光栅作为反馈元件构成外腔半导体激光阵列,对其输出光谱特性进行了实验研究,分析了快轴准直透镜的位置对外腔反馈耦合效率的影响。实验结果表明,在体布拉格光栅外腔反馈作用下,半导体激光阵列输出光谱中心波长得到锁定,同时输出线宽显著变窄。重点研究了体布拉格光栅的反射率对外腔反馈半导体激光阵列输出光谱特性以及激光器效率的影响。实验结果表明,体布拉格光栅反射率的增加可提高半导体激光阵列内腔模式的抑制效果,提高输出光谱对比度,减小输出光谱线宽。使用反射率为30%的体布拉格光栅,可将半导体激光阵列的输出波长锁定在808nm附近,输出光谱线宽压缩至0.18nm。外腔半导体激光器的输出功率达24.8W,效率为82.6%。     

光纤光栅外腔半导体激光器的理论及实验研究

对影响光纤光栅外腔半导体激光器特性的几个重要因素(光纤光栅长度、耦合系数、内腔反射系数)进行了理论分析和数值模拟。从实验上进行了验证,实测了不同反射率情况下激光器的激射光谱,得到了带宽为0.1nm、出纤功率达417.4μW、边模抑制比高达37.9dB的激光谱线。验证的结果表明,理论分析、数值模拟、实验结果是吻合的。     

光纤光栅外腔反馈的高功率半导体激光器光谱特性的研究

对光纤光栅外腔反馈的高功率半导体激光器的光谱线宽特性进行了理论与实验研究。理论分析表明，根据不同的外腔参数，激光器的线宽能被压缩或展宽。外腔反射率对光谱线宽的影响要比外腔腔长灵敏得多。实验实现了激光器的线宽由６ｎｍ到０．８ｎｍ的压缩。光纤光栅外腔反馈不仅能改善高功率半导体激光器的光谱特性，而且可提高激光器主模对次模的抑制比。     

双波长可调外腔半导体激光器

提出了一种基于体布拉格光栅（VBG）和横向啁啾体布拉格光栅（TCVBG）组合的双光栅外腔半导体激光器,该外腔半导体激光器采用反射率15%的体光栅和反射率17%的啁啾体布拉格光栅作为反馈元件和模式选择元件,实现特定波长的选择和调谐,实验研究了外腔激光器的功率-电流特性、光谱特性和波长调谐特性。实验结果表明:双光栅外腔半导体激光器最大输出功率为1.96 W,斜率效率为0.94 W/A,外腔效率达到78%。输出光谱为双波长,一个波长为808.6 nm,另一个波长连续可调,通过改变横向啁啾体光栅的位置,该波长可从800 nm调谐至815 nm,可调范围达15 nm,在整个可调范围内两个波长的谱线宽度（FWHM）均小于0.3 nm。     

光纤端面反射率对光纤光栅外腔半导体激光器的输出影响

为了实现光纤光栅外腔半导体激光器良好的单纵模输出,通过加入空气间隙区改进了基于射线法的光纤光栅外腔半导体激光器理论模型,并结合稳态速率方程研究了小注入情况下,光纤端面反射率对激光器输出特性的影响。仿真结果表明,在光纤端面反射率与光栅反射率可比拟的情况下,减小光纤端面反射率,可增大主模与其他波长模式的损耗差异,加强光纤光栅的选模作用,更好的实现单纵模输出,但同时也会增大激光器的阈值电流。     

F-P短耦合腔动态单模半导体激光器

短耦合腔(SCC)半导体激光器通常由半导体激光二极管和外腔反射镜直接耦合组成,由于复合腔损耗调制作用而实现高速调制下的单纵模输出。本文提出的F-P短耦合腔动态单模激光器是以F-P标准具做外反射镜的新结构器件。理论计算表明,参数匹配的F-P SCC激光器,边模与主模的损耗差较单一平面外腔SCC激光器提高约50%,因而将大大有利于实现动态单模输出并提高边模抑制比。理论分析还表明,在激光二极管外腔一侧解理面上镀增透膜对选模有重要意义;选择厚约50～150μm,两面反射率分别为20～40%和约100%的标     

一种可降低Littman-Metcalf光栅外腔半导体激光器衍射损耗的结构设计

基于原有Littman-Metcalf型光栅外腔半导体激光器的工作原理,设计了一种可以降低衍射损耗的外腔结构。在Littman-Metcalf结构的基础上增加一个反射镜,将闪耀光栅二次衍射产生的零级衍射光反馈回半导体激光器本征腔。推导了新结构模型外腔损耗的表达式,通过等效腔的概念对两种结构激光器的外腔损耗、阈值电流、输出线宽以及输出功率进行了仿真分析。结果表明：将二次衍射产生的零级光反馈回有源区可有效降低Littman-Metcalf结构激光器的外腔损耗,提高了系统的耦合效率,从而降低阈值电流,提高了激光器的输出功率。同时,由于提高了外腔反射效率,该外腔结构进一步压窄激光器的输出线宽。对影响低损耗Littman-Metcalf外腔激光器输出线宽以及输出功率的因素(端面反射率、内外腔长、闪耀光栅衍射效率以及反射镜反射率等)也进行了仿真分析,为后期激光器制作提高了理论指导。     

Wavelength switching of picosecond pulses in a self-seededFabry-Perot semiconductor laser with external fiber Bragg gratingcavities by optical injection

All-optical wavelength switching of single-mode picosecond pulses was demonstrated in an optically gain-switched Fabry-Perot semiconductor laser with self-seeding from two uniform fiber Bragg gratings (FBGs) or a linearly chirped FBG by injecting optical pulse trains with a peak power of ~1.0 mW at GHz repetition rates. Sidemode suppression ratio (SMSR) better than 17 dB was achieved in both wavelengths in the former case. Wavelength switching among three successive laser cavity modes was achieved in the latter case. A SMSR better than 15 dB was obtained at all three wavelengths. This laser has potential applications in remote optically controlled fiber sensors, such as temperature sensors     

环形腔高掺Er3 窄线宽光纤激光器实验研究

报道了采用光纤光栅（FBG）短直腔选频结构的环形腔窄线宽光纤激光器。采用约3m长高掺Er^3光纤，LD抽运阈值功率约为11mW，在25mW976nm有效抽运功率时输出信号功率为2．65mW，斜效率约为15％；输出激光3dB线宽小于0．01nm，20dB线宽小于0．04nm，边模抑制比（SMSR）为48dB；观察到输出信号光波长漂移范围为0．06nm。     

Degradation of side-mode suppression ratio in a DFB laser integrated with a semiconductor optical amplifier

The degradation of the side-mode suppression ratio (SMSR) in a monolithically integrated distributed feedback laser and semiconductor optical amplifier (SOA) cavity is investigated. An expression is derived that gives the degradation of the SMSR in the case of a perfectly antireflection-coated SOA facet. The amplified spontaneous emission (ASE) backcoupling can have dramatic effects and degrade the SMSR of single-mode devices to unacceptable levels.     

1.5 mu m GaInAsP/InP distributed reflector (DR) laser with high-low reflection grating structure

A 1.5 mu m-wavelength dynamic-single-mode laser with high-low reflection grating structure aiming at high output and uni-directional output operation has been obtained for the first time using a selective etching process and low-pressure MOVPE regrowth. A front/rear output power ratio exceeding 50 and side-mode suppression ratio (SMSR) greater than 39 dB were obtained at 1.3 times the threshold.<>     

Self-seeding of Fabry-Perot laser diode for generating wavelength-tunable chirp-compensated single-mode pulses with high-sidemode suppression ratio

We report an effective technique for generating wavelength-tunable chirp-compensated single-mode pulses with a high sidemode suppression ratio (SMSR) based on self-seeding a Fabry-Perot laser diode. This technique relies on the use of a tunable linearly-chirped fiber Bragg grating to provide wavelength-selective feedback, output filtering, and chirp compensation. With this technique, we have generated chirp-compensated picosecond pulses with a SMSR higher than 40 dB over a tuning range of 11.5 nm.     

光纤光栅作为外反馈的混合腔半导体激光器

利用一个一端镀有增透膜的Ｆ－Ｐ腔半导体激光器芯片和一段反射率为５０％的光纤光栅组合成一混合腔激光器，腔长约为２ｃｍ。在５０ｍＡ的偏置电流下，主边模抑制比为３７．６ｄＢ，出纤功率为１ｍＷ。并对这种结构的激光器进行了初步的理论分析     

LD泵浦不同腔结构高效运转掺铥光纤激光器

研究了掺铥光纤激光器的不同谐振腔结构方式。使用LD泵浦,分别采用双色镜和端面反射、高反光纤光栅和端面反射以及双色镜和低反光纤光栅构成激光器谐振腔,均获得了超过Stokes极限的斜效率。其中双色镜和端面反射腔结构下获得了最高斜效率56.9%,对应的量子效率为142%。三种腔结构下,激光光谱线宽由激光器系统所采用的反射腔的光谱特性所决定。在双色镜和端面反射腔结构下,激光器在双色镜的高反带宽内随机起振,光谱较宽;在使用光纤布拉格光栅作为激光器谐振腔的高反射腔镜和低反射腔镜的情况下,激光器都获得了2 m处的窄线宽输出,线宽受限于所使用的光纤光栅的反射带宽。     

Long-wavelength InGaAsP/InP distributed feedback lasersincorporating gain-coupled mechanism

Successful operation of long-wavelength InGaAsP low-threshold-current gain-coupled DFB lasers was demonstrated by using an InGaAsP quaternary grating that absorbs the DFB (distributed feedback) emission. The amount of gain (loss)-coupling is controlled by the composition (bandgap) and thickness of the grating quaternary and the InP-spacer layer between the grating and the active layer. With optimally designed lasers, CW (continuous-wave) threshold currents were 10-15 mA (250-μm cavity, as-cleaved), slope efficiency was ~0.4 mW/mA (both facets) and SMSR (side-mode suppression ratio) was as high as 52 dB. The laser operated in the same DFB mode with SMSR staying ~50 dB throughout the entire current range. At 100°C, the CW threshold current stayed low, ~50 mA, and SMSR was ~40 dB. Results also indicate that the presence of gain-coupling removes the degeneracy in lasing wavelength     

SGDBR激光器中取样光栅的理论和实验研究

讨论了取样光栅分布布拉格反射激光器(SGDBR)中取样光栅对激光器调谐范围、输出功率和光谱质量的影响,介绍了其设计流程,并据此对SGDBR进行了实验研究.其取样光栅的反射谱和设计相符,且在30nm准连续调谐范围内边模抑制比都大于30dB.     

Interrogating a Fiber Bragg Grating Vibration Sensor by Narrow Line Width Light

A method to interrogate fiber Bragg grating vibration sensor by narrow line width light is demonstrated. The interrogation scheme takes advantage of the intensity modulation of narrow spectral bandwidth light, such as distributed feedback laser, when a reflection or transmission spectrum curve of an fiber Bragg grating （FBG） moves due to the strain which is applied on the sensor. The sensor＇s response to accelerating frequency and amplitude is measured by experiment. The factors which have impacts on the sensitivity of the interrogation system are also discussed.