全光纤声光调制器的耦合模理论研究

利用适于普通通信光纤的耦合模方程,从理论上分析了一种全光纤声光调制器.并从理论上研究了基于普通通信光纤的全光纤声光调制器,得到了这种全光纤调制器的输出结果.     

压电式光纤相位调制器相移系数测试

介绍了压电式光纤相位调制器的相移系数理论公式,提出了基于杨氏双缝干涉原理的相移系数测量方法。对测量方法的可行性进行分析,通过实验对测量方法进行了验证。实际研制了一个基于压电陶瓷环的光纤相位调制器件,实验测得的相移系数与理论分析结果基本一致。利用研制的压电式光纤相位调制器实现了两路准直光束之间的相位锁定,在远场实现了相干合成,干涉条纹可见度从3%提升至43%。     

基于高功率激光输出端相位控制的光纤激光相干合成

利用压电陶瓷相位调制器在高功率光纤激光输出端进行相位控制,实现了两路瓦量级光纤激光相干合成.系统闭环时长曝光图样的条纹可见度为98%,峰值强度是开环情形下的1.87倍.     

共线外差干涉系统相位特性

以单束正交线偏振光为光源,利用索列尔-巴比涅相位补偿器使相位连续变化,采用锁相放大器进行数据采集,设计了一种由光纤耦合输出的窄频半导体激光器和双声光调制器组成的共线外差干涉系统,对其相位特性进行了研究,分析了激光束漂移及光源谱线宽度对相位测量的影响.实验表明:系统的相位分辨率为0.3611μm,相位灵敏度为27.386°/mm,测量误差为0.090rad;可以消除由声光调制器光强调制引起的相位误差,抑制激光束漂移引起的误差,以及减弱环境因素产生的噪声对测量结果的影响.     

多通道全光纤声光调制器的理论研究

对于全光纤调制，以前的研究者多着眼于单通道调制的研究。为了利用光纤的巨大承载能力，对多通道调制进行研究也是非常必要的。从理论上研究了多通道全光纤声光调制器。利用微扰形式的光纤耦合模方程，讨论了一根光纤多个部分受到周期性微扰的情况，并进一步讨论了多通道全光纤调制的情况，最后讨论了相位匹配条件下的输出结果。这对于实验、器件研究具有指导意义。     

基于压电陶瓷的光相位调制器的调制系数测量及验证

实现了一种快速简单有效的测量基于压电陶瓷(PZT)的光相位调制器相位调制系数的方法。利用光纤马赫-曾德尔(M-Z)干涉仪输出光强度与两臂相位差的函数关系,通过3×3解调算法可以计算基于PZT的光相位调制器的相位调制系数。实验中在M-Z干涉仪另一臂加上一个基于PZT的相位调制器以减小系统噪声的影响,并在相位生成载波(PGC)解调实验中作为干扰源。最后通过PGC解调方案解调出了3×3耦合器的第一路输出信号中的干扰信号,实验验证了所测量的结果,表明该方法是行之有效的。     

基于光纤多普勒效应的超声传感方法

通过光纤频移干涉技术测量了超声在光纤中产生的多普勒频移,提出一种光纤超声传感方法.将缠绕在压电陶瓷上的光纤环接入到频移干涉萨格拉克干涉仪中,以压电陶瓷作为超声波信号源,调节声光调制器使得干涉信号偏置在零点,达到系统灵敏度最高,通过干涉信号的频率和幅值测量到了超声引起光纤环中发生的多普勒频移,进而获得了作用在光纤环上的超声波信号.实验结果表明,用该方法测量超声频率的相对误差为0.001%,频响在所测量的20~200kHz范围内具有良好的线性.该方法在管道健康监测、固体内部裂缝监测、大型机械装备结构损伤监测等方面具有应用前景.     

压电换能器等效模型分析与阻抗匹配设计

声光可调滤光器(Acousto-optic tunable filter,AOTF)的衍射效率不仅与功率信号源的质量、声光晶体氧化碲(TeO_2)的切型有关,而且压电超声换能器的结构以及其阻抗匹配网络也对AOTF的衍射效率有很大影响。本文对X切型铌酸锂(LiNbO_3,LN)四层镀膜压电超声换能器的等效模型进行了分析,确定了声光介质存在时换能器的阻抗特性,利用射频微波仿真软件,设计了电感-电容复合匹配网络。将换能器压合在TeO_2上,用复色光作为光源进行了声光衍射实验,经仿真与实验验证表明,该匹配电路可以有效的改善压电换能器的阻抗特性,提高换能器带宽,提高能量传输效率,AOTF衍射效率最高可达92.67%。     

W波段电光相位调制器的设计与建模分析

W波段(2.73～4 mm)电光相位调制器(EOM)结构具有多参数和设计复杂的特点,参考共面波导传输线理论和EOM理论,结合三维电磁仿真高频结构仿真软件HFSS,对调制器进行有限元分析和计算。针对EOM几何结构中的关键参数,在4个维度上进行模型仿真计算,建立EOM的多维度数学模型。根据仿真模型,得到EOM几何结构参数与主要性能的变化规律,确立EOM的模型结构。通过结构优化,得到频率为100 GHz的EOM模型,调制器速率匹配,阻抗匹配,并且衰减较小。     

基于压电陶瓷与光纤电光调制器双通道伺服反馈的激光相位锁定实验研究

通过相干合束提高光纤激光源的输出功率是目前研究的一个热门领域,其中多束激光的相位控制是提高合束效率的关键技术之一.本文基于主动相位锁定技术对传统外差探测法进行了改进,基于压电陶瓷及光纤电光相位调制器双通道伺服反馈,实现了对同一激光源输出的两路相位独立变化的1531 nm激光长时间的相位锁定.通过选择合适的PID控制参数,将反馈带宽拓展到了220 k Hz(受限于PID控制器自身带宽).最终的相位锁定控制在0.88?以内,即相位控制精度为λ/400,经过160 s平均后可得到相位锁定的最佳值为0.006?,整体实验装置结构简单、运行稳定.     

New method for self-homodyne laser linewidth measurements with a short delay fiber

A versatile method for self-homodyne laser linewidth measurements is presented. The acousto-optic modulator used in the standard self-heterodyne technique is replaced by electronic upconversion. This results in reduced optical loss and a simpler setup. The dependence of the detected homodyne signal on the mean phase difference between the mixed beams was averaged out with a phase modulator on the delay fiber. A delay fiber shorter than the coherence length of the laser can then be used.     

Actively mode-locked visible upconversion fiber laser

Active mode locking of a Pr(3+)/Yb (3+) -doped upconversion fluoride fiber laser with an all-fiber ZnO acousto-optic phase modulator is demonstrated for the first time to the authors' knowledge. Optical pulses of ~550-ps duration with a repetition rate of 239 MHz at a wavelength of 635 nm have been generated.     

Optical phase locking in the microradian domain: potential applications to NASA spaceborne optical measurements

We have constructed and demonstrated a high-performance optical phase-locked loop between two cw Nd:YAG lasers. The feedback system is relatively simple, employing only the laser's internal piezoelectric transducer and an external acousto-optic modulator. A residual phase noise of the order of 1microrad between two optical fields is achieved in the locked condition, as is verified by time- and frequency-domain analyses by the two-oscillator approach that is conventionally used in rf measurement. Potential applications to NASA space-based optical measurements are discussed.     

Full phase stabilization of a Yb:fiber femtosecond frequency comb via high-bandwidth transducers

We present full phase stabilization of an amplified Yb:fiber femtosecond frequency comb using an intracavity electro-optic modulator and an acousto-optic modulator. These transducers provide high servo bandwidths of 580 kHz and 250 kHz for f(rep) and f(ceo), producing a robust and low phase noise fiber frequency comb. The comb was self-referenced with an f-2f interferometer and phase locked to an ultrastable optical reference used for the JILA Sr optical clock at 698 nm, exhibiting 0.21 rad and 0.47 rad of integrated phase errors (over 1 mHz-1 MHz), respectively. Alternatively, the comb was locked to two optical references at 698 nm and 1064 nm, obtaining 0.43 rad and 0.14 rad of integrated phase errors, respectively.     

移相干涉术的新方法—声光变频移相法

提出了一种变频移相的方法，并用声光器件作为变频移相器件进行了移相干涉实验，这种方法可以完成压电陶瓷移相方法无法实现的一些移相干涉测量。     

Characteristics of a Q-switched multicore photonic crystal fiber laser with a very large mode field area

We model and characterize the behavior of a Q-switched fiber laser. The fiber is a doped multicore photonic crystal fiber having six cores in a ring-type geometry. The fiber laser is Q-switched using an intracavity acousto-optic modulator. Using a mode filtering technique in the far field, a mode very close to the fundamental in-phase supermode is obtained with a mode field area of 4200 microm(2) and a divergence of 9 mrad. Pulses with energies of up to 2.2 mJ and durations of 26 ns (limited by end facet damage) at a repetition rate of 10 kHz are obtained.     

用压电陶瓷实现的光纤相位调制理论与实验分析

本文对用PZT实现的光纤相位调制理论进行了分析,推导了PZT外施电压与相位变化量之间的数学关系式.最后,通过实验验证了该理论的正确性.     

High-resolution, large dynamic range fiber length measurement based on a frequency-shifted asymmetric Sagnac interferometer

We propose and experimentally demonstrate a single-mode fiber length and dispersion measurement system based on what we believe to be a novel frequency-shifted asymmetric Sagnac interferometer incorporating an acousto-optic modulator (AOM). By sweeping the driving frequency of the AOM, which is asymmetrically placed in the Sagnac loop, the optical length of the fiber can be determined by measuring the corresponding variation in the phase delay between the two counterpropagating light beams. Combined with a high-resolution data processing algorithm, this system yields a dynamic range from a few centimeters to 60 km (limited by our availability of long fibers) with a resolution of approximately 1 part per million for long fibers.     

Actively mode-locked fiber ring laser by intermodal acousto-optic modulation

We report an actively mode-locked fiber ring laser. A simple and low-insertion-loss acousto-optic modulator driven by standing flexural waves, which couples core-to-cladding modes in a standard single-mode optical fiber, is used as an active mechanism for mode locking. Among the remarkable features of the modulator, we mention its high modulation depth (72%), broad bandwidth (187 GHz), easy tunability in the optical wavelength, and low insertion losses (0.7 dB). The narrowest optical pulses obtained were of 95 ps time width, 21 mW peak power, repetition rate of 4.758 MHz, and 110 mW of pump power.