超辐射发光二极管光源的分析与补偿研究

针对SLD(Super-luminescent Diodes)光源的光功率和中心波长会随着驱动电流和工作温度的漂移而发生变化的现象,通过SLD的工作原理对该现象进行了理论分析,基于8脚蝶型SLD光源的实验,分析了光功率和中心波长受电流和温度变化的特点,分别建立了光功率和中心波长随驱动电流和工作温度之间关系的非线性数学模型,设计了SLD光源参数不稳定性的补偿方案,对SLD光源参数不稳定性引起的漂移进行补偿,从补偿前后光纤陀螺的测试输出脉冲数据可以看出,该补偿方法可以有效地改善光纤陀螺的在复杂工作环境下的长期稳定性,降低了光纤陀螺对恒流、恒温电路的要求。     

保偏膜式光学玻璃电流传感头温度特性理论分析

用理论分析和计算机仿真的方法研究了环境温度变化导致的光源中心波长移动和传感头材料Verdet常量与应力双折射变化对光学电流互感器输出性能的影响.结果表明：环境温度由10℃变化到30℃时，归一化尺度因子降低了1.379%.其中光源中心波长随温度的变化对输出尺度因子的影响大于其他光学参量温度特性的影响.因此，在光学电流互感器设计中，必须采取必要的技术措施减小或补偿传感头温度特性对系统的不利影响.     

空间扫描型光纤法布里珀罗传感解调中LED光源的影响研究

结合恢复单色频率绝对相位解调算法研究了光源输出参数对空间扫描型光纤法布里珀罗传感解调影响。建立了相位解调值随光源中心波长变化的数学模型,通过改变光源光功率和光谱进行了解调实验研究。结果表明压力解调值的误差值与光源输出光功率有关;当温度升高时光源光谱会产生红移,使压力解调值产生误差;解调值与光源光谱中心波长满足二次函数关系。实验结果与理论分析一致,在140kPa范围内保证0.1%的解调误差时,光源光谱中心波长波动小于1.79nm。     

掺铒光纤超荧光光源平均波长温度稳定性实验研究

研究了掺铒光纤超荧光光源平均波长温度稳定性与光源结构和泵浦功率的关系,分析了不同结构和泵浦功率情况下平均波长随温度变化的原因.通过改变光源的结构和泵浦功率,改善了光源的输出光谱形状和吸收发射特性,从而改善了平均波长的温度稳定性.满足一定参量条件的双程后向结构光源,平均波长全温稳定性可达到1 ppm/℃,比目前实测的10 ppm/℃高将近10倍,且输出功率高而稳定.     

基于掺铒光子晶体光纤超荧光光源的实验研究

为了改进传统掺铒光纤超荧光光源的输出稳定性,提出基于掺铒光子晶体光纤的超荧光光源。构建了单程后向结构掺铒光子晶体光纤超荧光光源,研究了这种新型光源的输出特性。分析了掺铒光子晶平均波长体光纤长度和抽运功率对光源输出功率、光谱谱宽和平均波长的影响。结果表明,通过优化选取光纤长度28m和抽运功率220mW,获得了单程后向结构超荧光光源输出如下:输出功率45.74mW、光-光转换效率20.79%、谱宽31.5nm和平均波长1548.003nm。该实验结果为进一步研究掺铒光子晶体光纤超荧光光源在不同环境下的稳定性奠定了基础。     

大功率高效率掺铒超荧光光纤光源及其应用

采用光纤反射环镜和双程后向结构,得到了最大输出功率30.6 mW、光光转换效率42.0%的大功率、高效率全光纤掺铒超荧光光源（SFS）.利用串接光纤光栅（FBG）和光纤型F-P腔,对其进行光谱分割,得到了稳定的多波长输出.实验结果和探讨对光谱分割多波长光源的研制具有指导意义.     

基于光谱线性拟合的宽波段光源波动补偿方法

宽波段光源在工作过程中,光强通常会随供电电源输出功率的变化而波动。宽波段光源波段内各个波长的光谱强度将会发生不同程度的波动。为解决光源光强波动时其波段内各个波长光谱强度的补偿问题,提出了一种基于光谱线性拟合的补偿方法。使用这种方法,只需测量光源波段光强的变化,就可以补偿各个波长光谱强度的波动。通过分析理想黑体全波段辐射出射度与光谱辐射出射度的近似线性关系。建立了宽波段光源波段光强与光谱强度的线性模型。实验装置主要由卤素灯珠、光源电源、光阑、光谱仪及计算机构成。调节电源的输出功率,得到一组卤素灯珠在不同输入功率下的相对光谱强度。测量不同功率下卤素灯珠光谱强度来验证该方法补偿效果。按线性关系拟合了卤素灯珠光谱强度与其波段光强关系式,并分析了拟合误差。实验表明：卤素灯珠的光谱强度与其波段光强具有很好的线性关系,可以用波段光强按线性关系来补偿其光谱强度的波动。随着卤素灯珠输入功率的增大,补偿后的光谱强度的相对误差绝对值下降。在卤素灯珠输入功率范围内,使用该方法补偿的光谱强度在绝大部分(92%)波长下相对误差绝对值可在5%以内。     

光纤陀螺用掺铒超荧光光纤光源输出特性研究

介绍了掺铒超荧光光纤光源(SFS)的基本原理和SFS各种基本结构的特点。结合实际应用选择了单程后向(SPB) SFS作为光纤陀螺用光源。理论分析了影响单程后向掺铒超荧光光纤光源输出特性的各种因素。通过实验分析了铒纤长度对单程后向掺铒光纤光源泵浦效率和输出光谱的影响,特别是对中心波长稳定性的影响,对于单程后向结构掺铒光纤光源来说,铒纤长度有一个最佳值。演示了铒纤在选择最佳长度的情况下,泵浦功率对输出谱型的影响。通过实验分析了-40℃～60℃之间光源输出光谱和输出光功率的温度稳定性。最终得到了适用于惯导级光纤陀螺的光源。     

大功率、高效率、高消光比铒光纤多波长超荧光光源

采用改进的反射式Mach-Zehnder干涉滤波器，对双程后向结构掺铒光纤超荧光光源(DPB SFS) 分别进行光谱分割和光谱预分割，构建了两种结构的多波长超荧光光纤光源（MW SFS），波长间隔为～0.8 nm时，在1550 nm附近（1542～1559 nm）20个波长的功率波动小于0.5 dB其中前者消光比高达27 dB；后者消光比～18 dB，在泵浦光功率为72.8 mW时，最大输出功率25.3 mW，光光转换效率高达34.8%改变Mach-Zehnder干涉仪的臂长差，采用光谱预分割技术，得到1550 nm附近波长间隔～0.4 nm、消光比～16 dB的50个波长输出     

掺铒光纤非线性耦合器的实验研究

提出一种耦合参量可用光调控的掺铒光纤非线性耦合器.用熔融拉锥法熔合两根掺铒光纤，拉制成工作波长为155nm的3dB掺铒光纤耦合器.通过调变输入耦合器一臂的980nm泵浦光功率，可以改变两臂的传播常量差，从而改变耦合器两臂信号光的相对输出功率.通过测量输入泵浦光功率和两臂信号光输出功率，得到直通臂耦合比依赖于泵浦光功率的实验曲线.实验研究表明，当泵浦光功率从0 mW变化至20 mW时，耦合比的变化可达到40％.与理论模拟的结果一致.     

基于FFP-TF2滤波器的可调谐激光器

可调谐激光器在光纤传感和光纤通信中有着广泛的应用，引起了人们的广泛重视。设计并搭建了基于FFP-TF2滤波器的可调谐激光器系统。通过FPGA设计的基于DDS (direct digital frequency synthesis)函数信号发生器与模拟放大电路结合产生的驱动电压，调节FFP-TF2腔长的变化，进而改变激光器的输出波长。该系统可以实现对FFP-TF2单点电压和扫描电压的驱动，从而激光器可以输出单波长激光和多波长扫描激光，在激光器输出波长1 532 nm~1 568 nm范围内，可以调节单波长输出，也可以调节多波长扫描范围，且两种模式可以切换使用。实验结果表明，激光器输出3 dB线宽基本保持在0.01 nm左右，激光器输出中心波长与驱动电压线性拟合度为99.934%，灵敏度为3.915 nm/V，而FFP-TF2输出中心波长与驱动电压线性拟合度为99.986%，灵敏度为4.021 nm/V，激光器输出中心波长相对FFP-TF2的误差为2.6%，说明该激光器系统输出波长具有线宽窄、稳定性好、灵活性高等优点。     

量子点半导体光放大器波长转换的Q因子特性

为了改善全光波长转换器的转换性能进而提高输出信号质量,研究了波长转换器的Q因子特性。采用牛顿迭代法和四阶龙格库塔法解光场传输方程和跃迁速率方程,分析了输入信号光功率、脉冲宽度、最大模式增益和有源区长度4个因素对全光波长转换器的Q因子特性的影响,并将得到的结果与相同条件下的输出消光比比较。结果表明:增大输入信号光功率,Q因子先增大后减小,并且在-12 d Bm时取得最大值8.819 d B;Q因子随着脉冲宽度的增加而不断下降;增大最大模式增益和有源区长度,Q因子增大。在实现波长转换的基础上,优化各参数数值,得到的Q因子达到16.680 d B,输出信号质量较好。要同时获得高的消光比和Q因子,提高输出信号的质量,必须选取适当的输入信号光功率、脉冲宽度、最大模式增益和有源区长度。     

Effect of radiation-induced color centers absorption in optical fibers on fiber optic gyroscope for space application

The effects of color centers' absorption on fibers and interferometric fiber optical gyroscopes(IFOGs) are studied in the paper. The irradiation induced attenuation(RIA) spectra of three types of polarization-maintaining fibers(PMFs), i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers' absorption on RIA and mean wavelength shifts(MWS) at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient(RWC) degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.     

Characterization of fiber Bragg grating for maximum reflectivity based on modulation depth of refractive index

This study proposed the modeling of fiber Bragg grating as a sensor for the optimum reflectivity with minimum discontinuities at the end of center wavelength. Recent advancement in optical sensor technology, make it necessary to generate the optimum results with minimum error. In this analysis, dependence of grating output spectra on various parameters has been studied for minimum bandwidth, side lobes and maximum reflectivity. In previous studies effect of length and other parameters has been studied. In this paper author has included the effect of modulation depth also. Study shows that grating length and modulation depth of refractive index of core are very critical factors which significantly alter the grating characteristics. Here low absorption third window of optical communication is used for the sake of low attenuation. All the simulation has done using GratingMOd software using transfer matrix method.     

Received power analysis due to antenna deformation based on wavelet in inter-satellite laser communication links

Arbitrary deformation of optical antenna caused by processing technique and complex outer-space environment in inter-satellite laser communications can degrade the performance of the system. It is crucial to study the influence of deformation on the high precision system. Wavelet expression is proposed in the paper for diversified distortions. The influence on received power is investigated with the consideration of location, scale and depth of the deformation. Theoretical and numerical analysis show that the distortion attenuation factor increases with scale factor; with the location of the deformation shift from the center to the edge of the antenna, the distortion attenuation factor will increase till the whole deformation is away from the shelter of the secondary mirror, and then decrease; with the linear increase of depth, when the pattern of deformation can be well approximated by a constant value, the distortion attenuation factor will fluctuate periodically, or there will be no obvious variation regularity between them. It is hoped the study can help the optical devices selection and system compensation.     

Effect of radiation-induced mean wavelength shift in optical fibers on the scale factor of interferometric fiber optic gyroscope at a wavelength of 1300 nm

In order to analyze the effect of wavelength-dependent radiation-induced attenuation (RIA) on the mean transmission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes (IFOGs), three types of polarization-maintaining (PM) fibers is tested by using a ⁶⁰Co γ -radiation source. The observed different mean wavelength shift (MWS) behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible range and total dose-dependent near infrared absorption bands. To evaluate the mean wavelength variation in fiber coil and the induced scale factor change for space-borne IFOG under low radiation dose in space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium (Ge) doped fibers and two germanium-phosphorus (Ge-P) codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmitting in fibers will shift to shorter wavelength in low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOG.     

Effect of radiation-induced mean wavelength shift in optical fibers on the scale factor of an interferometric fiber optic gyroscope at a wavelength of 1300 nm

In order to analyze the effect of wavelength-dependent radiation-induced attenuation (RIA) on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes (IFOGs), three types of polarization-maintaining (PM) fibers are tested by using a 60 Co γ-radiation source. The observed different mean wave- length shift (MWS) behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium (Ge) doped fibers and two germanium-phosphorus (Ge-P) codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.     

Generation of 10-GHz duty-cycle tunable square optical pulse in an SOA-based mode-locked fiber laser

We demonstrate the generation of 10-GHz optical square pulses by injecting a picosecond pulse train into an SOA-based mode-locked fiber laser. The novel scheme exploits nonlinear effects and gain saturation phenomenon in the semiconductor optical amplifier (SOA). This technique uses gain-compression dynamics between the input pulses and the generated ones in gain-saturated SOA to form square pulses. The center wavelength of the generated optical square pulse can be tuned from 1530 to 1570 nm by adjusting the center wavelength of the optical band pass filter (OBPF) in the SOA-based mode-locked fiber ring laser. The duty cycle of the output pulse can be tuned from 12.7 to 88.4%, which strongly depends on the input power and intra-cavity power.     

低阈值852nm半导体激光器的温度特性

通过金属有机化学气相淀积(MOCVD)和半导体后工艺技术制备了852 nm半导体激光器,它在室温下的阈值电流为57.5 m A,输出的光谱线宽小于1 nm。测试分析了激光器的输出光功率、阈值电流、电压、输出中心波长随温度的变化。测试结果表明,当温度变化范围为293~328 K时,阈值电流的变化速率为0.447m A/K,特征温度T0为142.25 K,输出的光功率变化率为0.63 m W/K。通过计算求得理想因子n为2.11,激光器热阻为77.7 K/W,中心波长漂移速率是0.249 29 nm/K,实验得出的中心波长漂移速率与理论计算结果相符。实验结果表明,该半导体器件在293~303 K的温度范围内,各特性参数能够保持相对良好的状态。器件如果工作在高温环境,需要添加控温设备以保证器件在良好状态下运行。     

多芯片半导体激光器光纤耦合设计

应用ZEMAX光学设计软件模拟了一种多芯片半导体激光器光纤耦合模块,将12支808nm单芯片半导体激光器输出光束耦合进数值孔径0.22、纤芯直径105μm的光纤中,每支半导体激光器功率10 W,光纤输出端面功率达到116.84W,光纤耦合效率达到97.36%,亮度达到8.88MW/(cm2·sr)。通过ZEMAX和ORIGIN软件分析了光纤对接出现误差以及单芯片半导体激光器安装出现误差时对光纤耦合效率的影响,得出误差对光纤耦合效率影响的严重程度从大到小分别为垂轴误差、轴向误差、角向误差。