基于TE-TM模变换的新型相位自补偿磁光隔离器

讨论了由45°非互易模变换器与45°互易模变换器构成波导型光隔离器时两者之间须满足的条件,并由此设计了一种新型的相位自补偿磁光隔离器. 利用全矢量有限差分光束传输法对隔离器进行仿真,得到了插入损耗为-12dB,隔离度为-34dB的结果. 关键词： 集成光学 磁光隔离器 非互易模变换器 互易模变换器     

热敏电阻用于补偿Y波导温度漂移

铌酸锂集成光学相位调制器(Y波导)是数字闭环光纤陀螺的核心器件.温度变化引起相位调制器产生附加相位漂移,直接影响标度因数的稳定性,从而导致光纤陀螺零点漂移.因此,补偿温度引起Y波导附加相位漂移显得尤其重要.本文提出在Y波导驱动电路的运放电路中引入热敏电阻.利用热敏电阻的温度特性构建了温度补偿电路.温度变化引起运放电路放大倍数的改变,Y波导上调制电压的变化从而补偿温度引起Y波导的附加相位漂移.理论计算和实验结果证明,该方法可以简单、方便地提高光纤陀螺、光纤电流传感器等仪表的温度稳定性.     

锥形光波导中附加相位特性的分析

分析了不同过渡边界锥形光波导中的附加相位特性.采用近似公式分析了附加相位的改变趋势,进行了精确的数值计算.附加相位的改变量与锥形光波导各个几何参量相关并与波长敏感.提出可以利用变宽与变窄的锥形光波导进行波长敏感性补偿.     

电光聚合物波导中的锥形结构

提出并设计了一种基于电光聚合物的锥形波导,可用于单模光纤与电光聚合物波导器件之间的连接.锥形波导中采用了宽度锥形和折射率锥形结构.宽度锥形采用劈形形状,通过宽度和折射率的缓慢变化实现模场转换.劈形形状的宽度锥形具有较小的损耗且易于制作,折射率锥形可采用灰度掩膜光刻技术制作.研究了锥形波导的传输损耗与锥形波导的长度、波导宽度和厚度、材料吸收损耗等参数的关系及其优化,分析了锥形波导中的功率传输、模场分布与模式转换效率.结果显示锥形波导的传输损耗小于0.37 dB,光纤-波导-光纤的连接损耗优于1.62 dB,对插入损耗的改善达到8.78 dB,模场转换效率达到了83.7%.     

偏振模色散矢量的研究

研究了无损光纤的密勒矩阵,进而得出了偏振模色散矢量的解析表达式、主偏振态对应的斯托克斯矢量的解析表达式,以及高阶偏振模色散矢量的解析表达式.这些解析表达式是由光纤参数决定的.讨论了局部偏振模色散矢量与整体偏振模色散矢量的关系,讨论了利用偏振模色散矢量进行偏振模色散补偿的原理.引入了偏振模色散补偿元件的偏振模色散补偿矢量C,具体计算了正规的非圆光波导类的补偿元件的C.从理论上证明了仅仅利用一个正规的非圆光波导类的补偿元件,例如一根保偏光纤或是一个双折射晶体,是不能实现偏振模色散补偿 关键词： 偏振模色散 密勒矩阵 色散补偿 主偏振态斯托克斯矢量     

紧凑型圆极化模式转换器

 提出了一种结构紧凑的、能将圆波导TM01模或同轴波导TEM模转换为圆极化TE₁₁模的高功率微波模式转换器。该转换器由前后2个十字转门波导结对接组成,前者首先把圆波导TM₀₁模转变为4个矩形波导中的TE₁₀模,4个矩形波导的长度不等;后者再把4个经过不同相位延迟的矩形波导TE₁₀模转变为圆波导中的圆极化TE₁₁模。对所设计的1.75 GHz模式转换器进行了仿真研究,在中心频率上,该模式转换器转换效率为99%,轴比为0.03 dB;在1.575~1.900 GHz的频率范围内,转换效率大于90%,轴比小于2.5 dB,对应带宽为18.6%。     

光折变“波导”诱失锁模ps激光脉冲自泵浦相位共轭

观察到失锁模５３２ｎｍｐｓ激光脉冲单独入射到掺Ｃｕ的ＫＮＳＢＮ晶体中，不能产生自泵浦相位共轭，但如果先用同波长的锁模ｐｓ激光脉冲在晶体中预制一条光折变“波导”，则可诱导失锁模激光脉冲形成自泵浦相位共轭．分别从“波导”形成和时间分辨光谱等方面研究了这一现象 关键词：     

非简并光学参量振荡腔非稳特性研究

根据三模相互作用的半经典运动方程,讨论了参量下转换过程中非简并参量振荡腔的稳定性问题.研究表明:当信号光与闲置光的失谐量不一致时,腔内光场相位出现自调制现象.求出了产生自调制效应的阈值条件.讨论了自调制周期的参量依赖关系,并提出了通过耦合模强度自脉冲观测相位自调制的物理方法. 关键词：     

导模的功率衰减和转换特性的测量

本文在求解双模功率耦合方程的基础上,推得了导模的功率衰减和转换特性与光波导输入和输出功率的关系式.在离子交换玻璃波导上,将全息光栅和玻璃棱镜分别用作输入和输出耦合器,测得了光波导的输入和输出功率,并确定导模的功率衰减系数和功率转换系数.实验表明,这一测量方法是简便可行的,尤其适用于短波导样品的测量.     

太赫兹金属线波导耦合模理论研究(英文)

基于耦合模假设,研究了描述两太赫兹金属线波导之间耦合特性的耦合模理论.通过采用与光波导耦合模理论等价的近似,研究得到了耦合方程和耦合系数表达式.进而,研究得到了两个相同金属线波导的耦合方程解及耦合特性.所提出的理论对于描述两金属线波导之间的能量传递具有重要的意义.     

Operation principle of self-phase compensated optical waveguide isolator

A theory is developed for the self-phase compensated optical waveguide isolator recently reported in the literature. The operation principle of such device is explained in terms of synchronization of phase and power conversion. The effect of balancing phase mismatches of the two convertors on achieving a proper percentage of mode conversion is revealed. The way to make use of the phase mismatches of different sections to accommodate the different requirements in phase relationship for the reciprocal and nonreciprocal mode convertors is discussed. The theory is extended to the case where phase compensator is used. It is demonstrated that the introduction of phase compensator separates the adjustment of phase from the adjustment of power for the mode convertors so that relaxes fabrication tolerances of such devices. An isolator consists of three phase mismatched waveguide sections is designed and simulated. The simulation results confirm the self-phase compensation theory.     

Postnonlinearity compensation with data-driven phase modulators in phase-shift keying transmission

A novel scheme for postnonlinearity compensation is proposed to reduce the phase jitter in phase-shift keying transmission. A phase modulator is used to modulate the phase of the data pulses in front of the receiver. The magnitude of the phase modulation is proportional to the detected pulse intensity, and the sign is opposite to that of the nonlinear phase shift caused by self-phase modulation. Thus, the nonlinear phase noise induced by amplitude fluctuation and self-phase modulation is partially compensated for. We show by numerical simulations that a differential phase-shift keying dispersion-managed soliton system at 10Gbits/s with such postnonlinearity compensation can provide greater than 3dB of improvement in ultralong-haul dense wavelength-division multiplexing transmissions.     

Scaling of femtosecond Yb-doped fiber amplifiers to tens of microjoule pulse energy via nonlinear chirped pulse amplification

We demonstrate that the compensation of self-phase modulation by third-order dispersion can be exploited in the design of fiber amplifiers with tens of microjoules pulse energy. At the highest energies, the amplified pulse accumulates nonlinear phase shift as large as 17 pi. Gain-narrowing occurs in the final amplifier stage, but shorter pulses are still generated with larger nonlinear phase shifts. A large-mode-area Yb-doped photonic crystal fiber amplifier generates diffraction-limited 30 microJ pulses, which are compressed to 240 fs duration. These are converted to the second harmonic with 48% conversion efficiency, as expected theoretically, which confirms the pulse quality.     

基于频域相位共轭技术的交叉相位调制所致失真的复原

理论分析和讨论了基于频域相位共轭技术的交叉相位调制所致信号失真的复原和补偿机理，数值模拟了在交叉相位调制作用下，高斯脉冲在中距相位共轭光纤系统中的传输演化过程.结果表明，频域相位共轭技术能够抑制交叉相位调制对光纤系统中传输信号的损害，复原其所导致的信号失真，并能够同步补偿群速度色散和自相位调制非线性效应所导致的信号失真.合适的初始脉冲时延和初始脉冲啁啾有利于频域相位共轭技术对交叉相位调制所致信号失真的抑制. 关键词： 频域相位共轭 交叉相位调制 色散 自相位调制     

Theoretical analysis of self-phase locking in a type II phase-matched optical parametric oscillator

We analyze a doubly-resonant type II phase-matched optical parametric oscillator that includes an intracavity waveplate for inducing mutual injection locking between the signal and the idler. The intracavity waveplate provides a linear coupling between the normally orthogonally polarized signal and idler fields and allows for mode locking at frequency degeneracy. Under mode locked conditions the signal–idler phase difference is locked and the optical parametric oscillator becomes self-phase locked. The signal–idler phase can be adjusted by changing the operating point within the locking range. Two self-phase locked modes with different thresholds and signal–idler phases are possible. Characteristics of the self-phase locked regime are presented for different linear coupling strengths.     

半导体激光放大器用于啁啾补偿的研究

详细分析了饱和工作状态下的行波半导体激光放大器的啁啾特性，从理论上证了实了利用其增益饱和所引起的自相位调制来对光源啁啾和光纤色散进行啁啾补偿的可行性，并且发现，对于不同脉宽的入射脉冲，光放大器均能发挥相位补偿的作用，这一特性可用来在长距离光纤传输系统中，对微弱啁光脉冲同时进行能量和相位的补偿。     

Elimination of phase-matching requirement for optical waveguide isolator

A novel optical waveguide isolator based on self-phase compensated TE–TM mode conversion was proposed. In this work, the troublesome phase-match condition for the TE–TM mode conversion is eliminated without degradation on the performances. An isolator based on this mechanism is designed and simulated. An insertion loss of −0.1 dB and an isolation of −25 dB was obtained. The tolerance of fabrication and bandwidth of the isolator was also discussed.     

Stabilized generation of wavelength conversion by using high-accurate self-phase modulation based all-optical limiter

We demonstrate stable wavelength conversion by using our proposed high-accurate all-optical limiter based on self-phase modulation (SPM) with preventing serious influences of input intensity fluctuation. Wavelength conversion is one of the typical non-linear optical signal processing for the next generation of photonic networks. And it is very sensitive to input intensity fluctuation. To prevent serious influences of intensity fluctuation, it is necessary for intensity fluctuation compensation technique with high-accurate limiting function. To pursue high-accurate limiting function, we have proposed a new approach: applying pre-chirping pulses before inputting to the SPM fiber. By using our proposed limiter, the stabilization of the wavelength conversion is significantly improved, and we confirm that our proposed limiter is very effective for the stabilization of subsequent wavelength conversion processing.     

Observation of two distinct phase states in a self-phase-locked type II phase-matched optical parametric oscillator

We demonstrate self-phase locking in a type II phase-matched optical parametric oscillator by mutual injection locking. An intracavity quarter-wave plate provides polarization mixing between the orthogonally polarized signal and idler that induces signal-idler self-phase locking when their frequency difference is within the capture range. We observed two distinct phase states that differ in their oscillator thresholds and their signal-idler phase differences, in good agreement with theory.     

Compensation for self-focusing by use of cascade quadratic nonlinearity

We demonstrate theoretically and experimentally compensation for positive Kerr phase shifts with negative phases generated by cascade quadratic processes. Experiments show correction of small-scale self-focusing and whole-beam self-focusing in the spatial domain and self-phase modulation in the temporal domain.