Fiber-optic delay line using multicore fiber

A fiber-optic delay line based on a multicore optical fiber is fabricated for the first time. Due to the optical pulse sequential passage over all cores, the time delay of the optical signal of 45.0 μs is obtained at the optical fiber length of only 1300 m. The use of the seven-core optical fiber allows a sevenfold reduction in the used fiber length in comparison with single-core fibers, which is promising for developing lines with long signal delays.     

Bending dependence of optical delay difference between multicore fiber cores

The group delay difference between modes of multicore optical fiber cores is studied by the interference method using a Mach–Zehnder interferometer and a low-coherence radiation source. The data obtained show that the group delay difference between multicore optical fiber cores is caused by optical fiber bending and increases with decreasing winding radius.     

Controllable optical delay line using a Brillouin optical fiber ring laser

A controllable optical delay line using a Brillouin optical fiber ring laser is demonstrated and a large timedelay is obtained by cascading two optical fiber segments. In experiment, a single-mode Brillouin opticalfiber ring laser is used to provide Stokes wave as probe wave. We achieve a maximum tunable time delayof 61 ns using two cascading optical fiber segments, about 1.5 times of the input probe pulse width of 40ns. In the meantime, a considerable pulse broadening is observed, which agrees well with the theoreticalprediction based on linear theory.     

Polarization control in a large-stroke optical fiber delay line

In the context of an optical fiber delay-line implementation by use of silica fiber stretching capability, we experimentally demonstrate that highly birefringent fibers preserve their ability to maintain the polarization coherence in spite of the high magnitude of the stresses applied to them during large stretching. Two experimental demonstrations are presented. In the first, polarization cross coupling versus stretching is characterized. This stretching induces a variation of group delay in the span 0-45 cm. The second is a test of the fiber stretcher in an interferometric application.     

Microwave magnetostatic delay line

A magnetostatic delay line (MSDL) composed of a longitudinally magnetized YIG single crystal rod is constructed. The multiple round trip echoes observed, especially at short delay times, are sucessfully suppressed by changing the sample shape. At S-band the useful delay time controlled magnetically ranges from 0 to 0.5 μs. The untuned insertion losses at 2 and 4 GHz are ?26 dB.     

Reliability of multicore optical fibers in fiber-optic delay lines

Analytical expressions for estimating the minimum acceptable bending diameter are derived as a function of the expected service life, probability of premature fracture, and optical fiber diameter, which can be used to estimate the multicore optical fiber functionality in the particular applications.     

All-optical tunable delay line based on wavelength conversion in semiconductor optical amplifiers and dispersion in dispersion-compensating fiber

We demonstrate an all-optical continuously tunable delay line system based on wavelength conversion in semiconductor optical amplifiers (SOAs), and group-velocity dispersion (GVD) in a dispersion-compensating fiber (DCF). The system operates, near 1550 nm, with a non-return-to-zero (NRZ) pattern at 10 Gb/s. A maximal optical delay up to 2700 ps is observed. The scheme achieves continuous control of a wide range of optical delays, wide signal bandwidth, nearly no pulse broadening, and very little spectral distortion.     

A novel method for measuring optical fiber delay lines based on the optical fiber low-coherence Young's interferometer

According to the principle of double-beam interference imaging using an infrared broadband light source, a novel method based on the optical fiber low-coherence Young's interferometer for the measurement of programmable optical fiber delay line is proposed. By measuring the small length increments of delay fiber through the evaluation of the central positions of zero-order interference fringes, we successfully construct a system with a variety of important functions, such as real-time controlling, measurement and displaying. This system offers the benefit that it can be regulated precisely to generate interference stripes once again after the length of fiber segment changes. When the locations of central stripes are moved to coincide with the original markers, the determination of the corresponding fiber optical delay time becomes really simplified, as just by reading out the tinny displacement of the reference arm. Multiple groups of experimental results demonstrate the outstanding performance of the proposed system since it bears a measuring accuracy of μm and a measuring range from 1 mm to 20 cm.     

基于磁光开关的高精度光实时延时线

 给出了基于高速磁光开关的光实时延时技术的方案。研究了拓扑结构和磁光开关对光延时性能的影响。研制了5 bit,32位的光实时延时系统,并建立了光延时的测试平台,经测试,延时线延时精度优于3 ps。对光延时单元插损进行测试,结果显示:32态单元插损为0.12~0.88 dB,各态变化呈随机性。     

基于磁光开关的高精度光实时延时线

给出了基于高速磁光开关的光实时延时技术的方案。研究了拓扑结构和磁光开关对光延时性能的影响。研制了5 bit,32位的光实时延时系统,并建立了光延时的测试平台,经测试,延时线延时精度优于3 ps。对光延时单元插损进行测试,结果显示:32态单元插损为0.12~0.88 dB,各态变化呈随机性。     

Full-range tunable optical delay line based on coupled and side-coupled resonators

An optical delay line based on a new kind of structure comprising coupled resonators and side-coupled resonators has been proposed and demonstrated. The structure has unique advantages in realizing tunable optical delay lines. The tuning range has covered almost the full range of the optical delay line, from minimum delay at which only one ring of the light pulse structure requires transmission, to maximum delay at which all rings are required. In addition, the input signal delivered from the input to output port travels the structure twice, thereby providing buffer delay that is twice longer than general coupled resonators.     

频域反射法光纤延时精密测量

本文提出了一种应用于光纤延时系统中实现光纤延时精密测量的新方法,用以提高光纤延时测量的精度和准确性.该方法以1064 nm激光调制信号作为光源,通过测量回波信号的幅值和相位信息得到被测通道的频率响应,采用快速傅里叶逆变换得到被测目标的延时信息,实现光纤延时测量.本文通过理论分析和延时测量实验对频域反射法与传统的时域测量方法进行对比,使用频域反射法在调制频率范围10—200 MHz,采样频率间隔0.5 MHz的实验条件下,实现了3.3 ps延时测量分辨率,并证明了该方法具有比时域方法更高的测量精度,测量结果的准确性更好.     

Two-axis bend measurement with Bragg gratings in multicore optical fiber

We describe what is to our knowledge the first use of fiber Bragg gratings written into three separate cores of a multicore fiber for two-axis curvature measurement. The gratings act as independent, but isothermal, fiber strain gauges for which local curvature determines the difference in strain between cores, permitting temperature-independent bend measurement.     

基于FPGA和单片机的多路信号光纤传输系统设计

基于FPGA和单片机技术,设计了多路信号光纤传输系统,利用单片机实现了模拟数据的高精度采集和通信信号的双向传输,利用FPGA实现了多路复杂信号的处理与传输。实验证明：该系统不仅能传输多路模拟与数字信号,以及低速数字信号与高速脉冲信号,还能实现双向CAN通信。与现有光纤传输系统相比,多路信号光纤传输系统不仅实现了多路复杂信号的采集,而且使用一根光纤实现了大容量多数据的双向传输,一方面减小了产品体积,另一方面降低了产品成本。     

Broadband continuum generation in an irregularly multicore microstructured optical fiber

A broadband continuum generation is reported in a novel multicore microstructured optical fiber (MOF) where irregular air holes are randomly distributed in cladding. By launching ultrashort light pulses from a Ti:sapphire laser into a 190-mm-long fiber of this type, we have observed a group of continua generated from different cores, each with distinct color. 20-dB bandwidth of the broadest continuum is 1260 nm with an average power of 143 mW. The result confirms that the multicore MOF can be fabricated, with different dispersion profiles tailored for specific supercontinuum (SC) generation towards practical applications.     

基于LabVIEW的光纤线路光功率信号实时采集系统

 为实时获取光纤内光功率信号,基于LabVIEW虚拟仪器编程语言,采用USB总线技术,结合光接收机和NI数据采集卡USB M6251构成的硬件平台设计了新型的高速采集系统。该系统克服以往光功率信号采集系统采样率低、单通道显示、界面交互能力弱、便携性差等缺点,实现了采样参数可控的双通道实时采集、显示、保存光功率信号等功能。该系统开发效率高,并通过实验证明其具有良好的人机交互能力,可靠性高,实用性强,能为各类光纤通信系统提供光功率信号监测功能。     

Data pulse distortion induced by a slow-light tunable delay line in optical fiber

We experimentally demonstrate an all-optical tunable delay line based on slow light induced by stimulated Brillouin scattering in a highly nonlinear fiber (HNLF) and study the distortion of data pulses with different pulse widths and the induced pattern-dependent distortion on non-return-to-zero data in slow-light systems.     

光纤延迟线在雷达信号处理中的应用

介绍了光纤延迟线的原理和结构。详细阐述了它在雷达信号处理中的应用,包括频谱分析、雷达目标仿真、相关处理以及相控阵雷达波束的形成与控制。简介了光纤延迟线未来的发展。结果是,在相控阵雷达方面,为提高抗干扰能力、分辨力以及雷达对多目标成像的能力,都要求大的瞬时信号带宽,而光纤延迟线相移器是一个很好的解决方案。     

A welded optical fiber signal splitter

Fiber optic signal splitters have been made by welding two etched fibers to a single unetched fiber. These splitters have both low loss and low fabrication cost.     

Compact optical delay line for long-range scanning

We proposed and demonstrated an optical delay line composed of all reflective components for long-range scanning without walk-off problem. The optical delay line consists of a retro-reflector, an inclined reflection mirror and a scanning mirror. The size of the optical delay line is within 2 cm × 2 cm and the scanning range can reach 2.9 mm when the beam is incident at the pivot of the scanning mirror and the vibration angle of the scanning mirror is 9.6°. The scanning range can be further increased when the pivot of the scanning mirror is laterally deviated from the incident beam. The optical delay line possesses the advantages that it is compact, easy to fabricate and can perform rapid scanning in large scanning range without walk-off problem. The optical delay line was demonstrated with a low-coherence reflectometer where the scanning rate was 400 Hz. A higher scanning rate can be achieved when a scanning component with higher scanning rate is applied.