一种全自动调节的锁模光纤激光器

通过在非线性偏振旋转环形腔中引入一种全光纤化的角度可调的起偏器,简化了被动锁模光纤激光器的结构,通过调节环形腔内的光纤起偏器和1/4波片的角度就能够实现锁模脉冲的输出。基于此简化结构,引入基于单片机的触发反馈电路,控制偏振片和波片的旋转状态,实现了腔内锁模脉冲的自动调节输出,得到平均功率为8mW的、重复频率为5.6 MHz的全自动锁模脉冲稳态输出。     

Design of a fiber polarizer based on an asymmetric dual-core photonic crystal fiber

We propose a novel optical polarizer based on an asymmetric dual-core photonic crystal fiber(PCF) with triangular lattice air-holes.The fiber is designed as that the effective indices of modes in the two cores are matched at one polarized state but mismatched at another polarized state.As a result,one of the polarization states is coupled to the other core and transferred into a high-order mode.The transmission properties of the polarizer are investigated by the semi-vectorial beam propagation method(SV-BPM...     

Wavelength tunability in a Nd-doped fiber laser with an intracavitypolarizer

When an intracavity polarizer is introduced into a Fabry-Perot Nd-doped fiber laser, wide wavelength tunability is achieved either by rotating the polarizer or by varying, the fiber birefringence with an in-line polarization controller. The intracavity polariser also produces considerable line-narrowing. A model based on birefringence dispersion is proposed     

熊猫型单偏振光纤

熊猫型(PANDA)单偏振光纤(SPSM)主要用来制作光纤起偏器、光纤陀螺、光纤激光器和光纤传感器,较以往出现的其他种类的光纤起偏器具有明显的优势。我所采用打孔组装工艺来制作,通过在纤芯两侧对称置入应力施加单元引起高双折射,以及利用光纤芯区附近X和Y轴向折射率的不对称设计的方法,有效的改变了X和Y两个轴向的有效折射率,使得导模LP01中的两个简并模HE11X和HE11Y分别截止于不同的波长,通过将工作波长（1300 nm）设计选择在它们之间,使其中一个偏振模式HE11X导通,而另一个偏振模式HE11Y处于     

Pulse-train uniformity in optical fiber lasers passivelymode-locked by nonlinear polarization rotation

The generation of uniform soliton pulse trains by additive pulse mode locking has been experimentally demonstrated in a birefringent fiber laser with a passive polarizer. Numerical simulations of pulse propagation around such a fiber loop are presented which reveal that this mode-locking scheme does not result in strictly uniform pulse trains. Rather, the train of output pulses exhibits periodic fluctuations in intensity and polarization. A model for the pulse dynamics is developed which shows that these fluctuations depend on the strength of the fiber birefringence and the alignment of the polarizer with the fast- and slow-polarization axes of the fiber. It is also shown that increased uniformity of pulse trains is achieved with near alignment of the polarizer with the slow axis of the birefringence     

Magnetically tunable hollow-core anti-resonant fiber polarizer

An in-line high efficient polarizer, composed of magnetic-ionic-liquid-adorned(MIL-adorned) hollow-core anti-resonant fiber(HARF), is theoretically proposed and experimentally demonstrated. The protocol is based on the selective conversion of polarization mode into leaky mode and attenuates quickly in MIL and the polarizer is featured by the magnetically tunable polarization extinction ratio(PER) and the thermally controllable operation bandwidth.     

A single-polarization fiber

We report an oPtical fiber which guides only one polarization. This fiber polarizer utilizes high modal birefringence (4.7 times 10^{-4}) to split the two polarizations of the fundamental mode and an ellipitcal depressed-index cladding to provide a steep wavelength-dependent tunneling loss to the fast axis mode. The stress-induced birefringence is created by an elliptical SiO2-B2O2inner cladding. A 4.7-m length of polarizer fiber exhibits an extinction ratio of 34 dB at a wavelength of 633 nm, with polarizing behavior over a bandwidth of 50 nm. Insertion loss of less than 1 dB has been observed for the guided linear-polarization mode. The polarizing band may be shifted from 620 to 525 nm by bending the fiber to a radius of 0.67 cm. Such fiber polarizers should find a variety of applications in fiber sensors, attenuators, isolators, wavelength filters, and tuners.     

Phase error bounds of fiber gyro with polarization-holding fiber

Phase error bounds for a fiber gyro with an imperfect polarizer are calculated assuming a broad-band source and high-birefringence fiber. The phase error and resulting zero-point drift is related to the polarization-holding parameterhof the fiber. Comparison of the theory with recent experimentally observed bias drift is made.     

光纤环形激光器中锁模脉冲均匀性的理论分析和实验研究

从描述双折射光纤环形激光器动力学模型出发，模拟并分析了脉冲序列在非线性偏振旋转锁模光纤激光器环形腔内的演化过程，得出光纤快慢轴与起偏器之间的角度、以及双折射强度是影响锁模脉冲序列均匀性的重要因素，通过将普通单模光纤绕制成环产生应力双折射的方法进行了验证，并获得了中心波长1566．8nm、脉宽为1．5ps的稳定短脉冲序列。     

In-line optical fiber polarizer and modulator coated withLangmuir-Blodgett films

In-line optical fiber polarizer and modulator were fabricated by depositing Langmuir-Blodgett (LB) films on polished fiber surface with gold layer. The thickness of LB film was adjusted by changing the number of monolayers, which then optimized the performance of the fiber polarizer. Good agreement was observed between the theoretically predicted conditions for efficient coupling and the experimentally determined conditions for high TM/TE extinction ratio of the optical field. By applying an electric field between the LB film, the polarization state of the lightwave in the optical fiber can be modulated     

组合式快速变极化器设计

研制了一种用于雷达极化捷变的组合式双模锁式快速变极化器,采用双模铁氧体可变移相器、固定介质移相器和正交模耦合器组合方式的变极化器具有体积小、设备量少、极化转换响应速度快的特点。铁氧体采取闭锁式磁化方式能显著减小开关时间。给出了组合式极化器主要构成部件的仿真和实验结果,研制的变极化器在5400±60 MHz频带范围内极化隔离度≥30 dB,插入损耗L≤0.83 dB,端口驻波比≤1.10,极化转换时间36.6μs。     

A widely tunable narrow linewidth semiconductor fiber ring laser

We have demonstrated a novel approach to obtain a 0.1-nm line width laser with 38-dB sidemode suppression by utilizing a 1.3-μm semiconductor optical amplifier in a fiber unidirectional ring that consists of a linear polarizer and polarization controllers. The laser has a low-threshold current of 22.5 mA as well as a wide tuning range of 28 nm. The new approach is applicable to the 1.55-μm region as well. It is expected that nanosecond wavelength tuning speed is feasible using this approach in conjunction with fast electrooptic polarization controllers, short cavities and low-cavity losses     

Bidirectional single-mode Er-doped fiber ring laser

Rare Er-doped fiber lasers have been studied for fibe sensor applications with the advantage of frequency readou [1,2]. Due to this advantage, gyroscope application for a bidi rectional Er-doped fiber-ring laser was also demonstrated They also have high s…     

Distributed feedback laser diode (DFB-LD) to single-mode fiber coupling module with optical isolator for high bit rate modulation

A distributed feedback laser diode (DFB-LD) module for single-mode fiber coupling is described in the 1.5-μm wavelength region. An optical isolator is constructed in the two lens coupling circuit to stabilize the DFB-LD characteristics. It consists of a DFB-LD as a polarizer, a yttrium iron garnet (YIG) plate and an analyzer. Coupling characteristics and attainable isolation of the proposed circuit have been studied theoretically and experimentally. The effect of reflected light on the DFB-LD characteristics such as relative intensity noise (RIN) and oscillation spectrum has been experimentally investigated taking into account the polarization of the reflected light. It has been clarified that the DFB-LD can function as an effective polarizer with an extinction ratio of more than 20 dB. The DFB-LD module was successfully fabricated to have stable spectrum characteristics and to sufficiently suppress the noise caused by reflections. It has been confirmed by a long haul transmission experiment that this module is applicable to large capacity optical fiber transmission systems.     

光纤电流互感器平均波长漂移变比误差

全温条件下(-40~60℃)测量精度误差较大是影响光纤电流互感器实用化进程的主要原因之一。传感光纤的维尔德常数随光纤内光波平均波长变化,导致系统输出变比漂移,从而降低系统的测量精度。理论分析了光谱平均波长与系统输出变比之间的关系,并通过实验验证了关系式的准确性。分别对光纤电流互感器光路各组成器件对通过光平均波长的影响进行了分析,实验测量了变温条件下平均波长变化的趋势以及程度。提出了起偏器与延迟光纤在变温条件下对平均波长影响的自补偿方案,有效的减小了传感光纤中平均波长的漂移程度。保证光纤电流互感器在变温条件下到达0.2 s级精度要求。同时为适应更高测量精度应用场合提供了参考。     

Design and performance of tuned fiber coil isolators

Optical isolators using coiled single-mode fibers with controlled birefringence have been thoroughly analyzed and tested experimentally. Isolation ratios as high as 44.5 dB with insertion losses (excluding coupling and polarizer losses) of 0.3 to 0.4 dB have been obtained at 633 nm. Analysis indicates that these devices will have >20-dB isolation over a spectral range of 2.5 nm or a temperature range of 36°C.     

A highly efficient polarized superfluorescent fiber source for fiber-optic gyroscope applications

We demonstrate a novel polarized superfluorescent fiber source (SFS) that increases the output power in the desired polarization by a factor of 1.96 over that of an unpolarized SFS at the same pump. This is achieved by inserting a polarizer at the optimal point in the bidirectionally pumped erbium-doped fiber of an unpolarized SFS. Stable pump-power-dependent mean wavelength operation and less sensitivity to the insertion loss, important for fiber-optic gyroscope applications, are obtained in this configuration.     

Novel gain measurement method without optical fiber alignment in a semiconductor optical amplifier

A novel chip gain measurement method for semiconductor optical amplifiers is proposed. By introducing the concept of a virtual optical source, the method eliminates the need for troublesome fiber alignment. The chip gain is obtained from the ratio of the optical filtered amplified spontaneous emission power to the virtual input one. We clarified the validity of the method theoretically, and successfully demonstrated gain measurement, comparing it with the conventional method with fine fiber alignment. The results agree well. The polarization dependence of the gain can also be estimated well by inserting a polarizer.     

Self-starting, passively mode-locked Fabry-Perot fiber solitonlaser using nonlinear polarization evolution

The authors demonstrate pure self-starting mode-locked operation in a fiber Fabry-Perot cavity. The laser produces 1.6 ps transform-limited soliton pulses by means of nonlinear polarization evolution in conjunction with an intracavity fiber polarizer. This laser system can be used for the generation and study of soliton pulses in the picosecond regime. With a careful choice of the fiber dispersion and fiber length, the system should also be able to operate in the femtosecond regime. The advantage of the system over existing self-starting fiber soliton lasers is that an optical isolator (an expensive component) is not required. The replacement of the two mirrors with fiber reflection gratings would make this configuration a truly all-fiber device