OTDR在光纤测量中的应用

介绍ＯＴＤＲ工作原理及主要性能参数;详细说明ＯＴＤＲ在光纤测量中参数的设置及测量方法;结合工作实践提出了ＯＴＤＲ在实际光纤测量中的几点经验和技巧。     

弱光反馈水平下光回馈传感器的模拟行为模型

反射或散射光光强的变化及系统的非线性都将导致干涉模型的变化,从而造成干涉信号波形的变化。这些变化将增加测量过程中数据处理的复杂性。本文基于Cadence公司的orcad10.5提出一种模拟行为模型来描述弱光反馈水平下光回馈自混合干涉现象,该方法减化了光回馈自混合干涉现象中非线性方程的求解过程。不仅建立了弱光反馈水平下光回馈传感器的模拟行为模型,搭建了软硬件结合的平台,同时也提供了一种对目标位移、速度、距离等进行测量的新的数据处理方法。     

Low-loss optical Y-branch

An optical Y-branch is described which, owing to its low losses, is suitable for use in both optical multiplexing systems and measuring equipment, Different methods of attenuation, temperature, near- and far-field measurements are given for the characterisation of the branch.     

Nonlinear optical susceptibilities of solvents

We have measured the nonlinear optical susceptibility coefficient governing self-induced changes in the state of elliptical polarization of a monochromatic beam in 10 common solvents. These are the first such measurements at 1060 nm. We show how our results may be used to estimate self-focusing in these solvents and to clarify other non-linear optical properties.     

光频标和光频测量研究的历史、现状和未来

本文综合评述了光频标和光频测量研究的历史、现状和未来。在上世纪最后的30年间，光频标已达到10^-11-10^-13量级的准确度，使长度单位“米”进行了重新定义，实际上成为时间单位秒的“导出单位”。最近三年来，该领域的研究出现了重大突破。这是由于飞秒锁模激光技术与光频测量技术两者出人意外的结合，使微波频标与光频标之间建立了简易可行的联系，使光频标的准确度和实用性达到了前所未有的高度，成为计量学和物理学中一个新的亮点。它的进一步发展必将给计量学和物理学带来深远的影响。     

Length and power dependence of self-adjusting optical fiber filters

Self-adjusting optical filters, which passively track the wavelength of the optical signal, have been demonstrated using two-beam interference in single-mode erbium-doped fiber. Pump-probe measurements of the filter response are reported for a range of doped fiber lengths and optical input powers     

Interferometer-less coherent optical range finder

A new coherent optical detection technique employing coherent frequency-domain reflectometry and a novel optical frequency sensor is demonstrated for high-precision optical path-length measurements. Using pulsed laser sources, an improvement of more than two orders of magnitude in spatial resolution over conventional optical coherent frequency domain reflectometry techniques is demonstrated. Varying degrees of spatial resolution ranging from several centimeters to a few hundred nanometers are achieved. High-precision distance measurement with long baseline is also presented     

磁流体热透镜耦合光磁效应用于高电压电流的光学测量

本报道将一种新的光学效应，即磁流体热透镜耦合光磁效应，应用于高电压电流测量的初步结果。该方法最大的特点是不用偏振光，避免了易受干扰人保偏装置，提高了信噪比，同时又具有光纤传输的优点，并使得该系统简单，经济，和国际 惯用的法拉第效应相比有可能推动电流光学测量实用化的进程。结果表明实验系统可以优于１％的精度测量０－５００Ａ范围的电流。     

Quantifying optical feedback into semiconductor lasers via thermal profiling

We show that thermal profiling can be used to monitor optical feedback into semiconductor lasers in photonic integrated circuits, where direct optical access is impractical. The optical output power of a laser, both free-running and when exposed to optical feedback, can be quantitatively determined from thermal measurements alone, without recourse to direct optical measurements. Furthermore, the shift in threshold current resulting from optical feedback can be determined from the thermal measurements, enabling quantitative determination of the feedback coupling efficiency into the laser.     

Thermal profiling: locating the onset of gain saturation in semiconductor optical amplifiers

Spatially resolved thermal profiling of a semiconductor optical amplifier enables measurement of the gain and saturation characteristics without recourse to direct optical measurements. We observe the spatial onset of gain saturation, quantify both the saturated and unsaturated gain, and accurately predict the optical output power. Effects such as suboptimal operating conditions are identified. Since this method is independent of optical measurements, it is ideal for use with integrated devices.     

Low-noise optical detection of a 1.1 Gb/s optical data stream

A low-noise, 1.1 Gb/s optical receiver has been built using a silicon a.p.d. and a GaAs f.e.t. The receiver sensitivity was evaluated using error-rate measurements, and for a bit error rate of 10?9, with no fibre, the measured optical sensitivity was ?37.0 dBm. These results are used as a basis for the calculation of maximum repeater spacings for 1.1 Gb/s systems operating at 0.85 ?m and 1.25 ?m wavelengths.     

可调光分路器/耦合器的实现技术及其应用

介绍了可调光分路器/耦合器的实现技术及典型应用。通过具体实施方案论述了可变透射率/反射率膜片技术和可变光纤耦合长度技术等可以用来实现可调光分路或可调光耦合;讨论了可调光分路器/耦合器在光通信系统及器件制作中的应用。     

高光反馈水平下光回馈传感器的模拟行为模型

基于Cadence公司的orcad10.5提出一种模拟行为模型来描述高光反馈水平下(适度光反馈水平和强光反馈水平)光回馈自混合干涉现象,该方法减化了光回馈自混合干涉现象中非线性方程的求解过程。不仅建立了高光反馈水平下光回馈传感器的模拟行为模型,搭建了软硬件结合的平台,同时也提供了一种对目标位移、速度、距离等进行测量的新的数据处理方法。     

Advanced envelope detection method with novel optical PLL for optical sampling trigger

An advanced envelope detection method has been developed with a novel optical PLL without electrical 10 MHz timebase synchronisation. The principle of this method and the results of 160 Gbit/s far-end measurements using this technique are presented.     

Down-scaling differential pairs of depleted optical thyristors

We present the results of a scaling study of monolithic differential pairs of optical thyristors. The devices are depleted thyristors, intended for high-frequency and high-sensitivity operation. According to the measurements, the optical switching energy scales with area and equals to 15 aJ/μm². The smallest pair with mesas of 10×15 μm² operates with 2.6 fJ of light input. Sub-femtojoule optical switching energy is expected in the near future     

GaAs-double-heterostructure lasers as optical amplifiers

The results of measurements on a GaAs-double-heterostructure (DHS) laser used as an optical amplifier are reported. The laser's amplifying guide is coupled to an optical fiber with a rectangular core. The laser amplifier can be operated either in the traveling-wave or the resonator mode. The gain, noise, and performance of the amplifier when driven hard into saturation were measured as a function of various parameters.     

Measuring timing jitter with optical cross correlations

The use of optical cross correlations for characterizing timing jitter is investigated. Applications, limitations, and correspondence to radio frequency measurements are presented and clarified. The probability density function of the timing jitter of semiconductor mode-locked lasers is deconvolved from the cross-correlation measurements with the aid of pulse characterization techniques.     

Beyond capacitive systems with optical measurements for yarn evenness evaluation

Yarn evenness is usually obtained with capacitive systems evaluating mass per unit length variations. More recently, optical sensors have been proposed. In this paper, we present experimental results of yarn evenness evaluation with an optical measuring system, sensitive to the light absorbed and diffused by a moving yarn. Results obtained with the optical sensor are compared with measurements performed by means of a capacitive commercial tester. Good agreement in measured count variation CV is obtained.

Moreover, optical and capacitive measurements, simultaneously done on the same thread, allow to obtain a reliable comparison between the two measurement methods, in particular for what concerns yarn signal spectrograms.     

Continuous measurement of optical fibre transmission loss characteristics during drawing process

An online measurement method using an optical rotary connector is proposed for continuously monitoring optical fibre loss characteristics during manufacture. This method provides a complete transmission loss spectrum and OTDR measurements of optical fibres during the drawing process. The results coincide with corresponding offline cutback measurements to better than ±0.2 dB/km.     

Integrated optical E-field sensors with a balanced detection scheme

Compact and nonperturbing integrated optical E-field sensors are used for electric field measurements. The theoretical sensitivity of an integrated optical sensor system is limited by the shot noise. In conventional sensors, however the minimum detectable electric field strength is limited by the relative intensity noise (RIN) of the laser diode. Achieving the theoretical sensitivity a new sensor system is presented. Using a balanced optical receiver both a signal gain and a reduction of the RIN at the optical receiver is obtained. The principle function and the potential of the balanced detection scheme in comparison with existing concepts as well as first measurements are presented, yielding a sensitivity of less than 300 μV/(m√Hz) with standard laser diodes and a receiving dipole length of 40 mm