Simple optical wavelength meter in 700?1200 nm wavelength region

A new type of portable optical wavelength meter using a quartz rotator has been developed, designed for fibre optic transmission systems. The peak wavelengths of both lasers and l.e.d.s in the 700?1200 nm wavelength region can be measured. The measurement error was within ±1 nm at wavelengths around 850 nm.     

Cutoff wavelength determination in single-mode optical fibres by measurement of equalisation wavelength

A simple interferometric method for indirectly determining a value for the cutoff wavelength of single-mode optical fibres is described. The technique is accurate and no stringent requirements are placed on the experimental equipment.     

1.55 μm wavelength region high-stability optical fibre lossvariation measurement using fibre coupler

A 1.55 μm-wavelength high-stability optical fibre loss variation measurement system, using a comparison method with an optical fibre coupler, was developed. Long-term stability within ±0.001 dB over a 120 hour period at a room temperature variation of ±2.2°C has been achieved     

Direct measurement of wavelength dispersion in optical fibres-difference method

A new method is described for direct and precise measurement of wavelength dispersion in the core of an optical fibre over a wide wavelength region.     

不等光程法太赫兹波段材料光学参数的精确测量

近20年,太赫兹科学技术发展迅速,太赫兹波与物质之间的相互作用成为研究热点。理论推导并实验验证了一种提高太赫兹波段材料折射率、吸收系数等参数测量精度的方法。以两种厚度的高密度聚乙烯板（3.5 mm、5.0 mm）为样品,将不等光程测量法与常规太赫兹时域光谱测量方法进行比较,分别获得了0.5~2.5 THz频率范围的高密度聚乙烯的折射率和吸收系数,结果显示两种方法测量样品的折射率和吸收系数有较大的差异。常规法和不等光程法得到的折射率分别为1.505和1.483。常规法在1.465 THz附近出现一个峰值,而不等光程法得到的吸收系数在1.166 THz和2.431 THz出现特征吸收峰。证明不等光程法能更加精确提取材料光学参数,并可以揭示常规方法无法测得的材料特征吸收峰,为太赫兹波段精确测量材料光学参数提供了新的方法。     

A method to measure dielectric parameters in 5–0.5 millimeter wavelength band

The method to measure parameters of dielectric plates by placing them into the Fabry-Perot resonator is modified to provide, relative accuracies: for the resonance frequency of the plate 10^?6; for the refractive index and the plate thickness 10^?4–10^?5; for the loss tangent 5%. Tje values of loss tangent which can be measured are from 10^?6 to 10^?1. The device calibration is performed by a gas frequency standard in 5–0,5 mm wavelength band.     

Reliable wide-area wavelength division multiplexing passive optical network accommodating gigabit ethernet and 10-Gb ethernet services

This paper proposes and demonstrates a reliable wide-area wavelength-division-multiplexing passive optical network (WDM-PON) with a wavelength-shifted protection scheme. This protection scheme utilizes the cyclic property of 2/spl times/N athermal arrayed-waveguide grating and two kinds of wavelength allocations, each of which is assigned for working and protection, respectively. Compared with conventional protection schemes, this scheme does not need a 3-dB optical coupler, thus leading to ensure the large loss budget that is suited for wide-area WDM-PONs. It also features a passive access node and does not have a protection function in the optical network unit (ONU). The feasibility of the proposed scheme is experimentally confirmed by the carrier-distributed WDM-PON with gigabit Ethernet interface (GbE-IF) and 10-GbE-IF, in which the ONU does not employ a light source, and all wavelengths for upstream signals are centralized and distributed from the central office.     

生物组织光学特性参量的图像测量研究

为了测量生物组织的光学特性参量,采用CCD漫反射法和透射法,通过分析CCD摄取的待测样品表面的漫反射光分布图像,利用漫射近似理论,实现了漫反射法对生物组织模拟液(intralipid-20%稀释液)、牛肌肉、猪肌肉和鸡胸肉光学特性参量的测量,获得了样品的吸收系数和有效散射系数;测量了不同浓度生物组织模拟液的透射光强度,根据Beer-Lambert定律,实现了透射法对光学特性参量的测量,获得了样品的散射系数,进而得到了有效散射系数;并将漫反射法和透射法对同种样品光学特性参量的测量结果以及他人的测量结果进行了比较。结果表明,漫反射法和透射法的测量结果有很好的吻合性,测量生物组织光学特性参量采用的CCD测量装置和处理方法具有较高的精度。     

Efficient large-frequency-shifted three-wave mixing in low dispersion wavelength region in single-mode optical fibre

In a low-loss single-mode fibre pumped with a 1.3 ?m Q-switched Nd:y.a.g. laser, an injected weak (~ 1 mW) signal has been strongly amplified and mixed efficiently with the pump (~ 70 W) to generate new waves (?1 W) at multiple wavelengths with total spectral range extended as wide as 660 cm?1.     

The optical constants of indium antimonide at 1.5K in the near millimeter wavelength region

The results of a determination of the optical constants of n-type indium antimonide at 1.5K in the spectral region between 4 and 40 cm^?1 are presented. The absorption spectrum was determined by the two thickness method, while the refraction spectrum was determined both by an extension of the two thickness method and by an analysis of a channel spectrum. The errors involved in the application of these approximate methods are discussed. The material measured was of detector quality and, therefore, the results are relevant to the design of near millimetre wavelength detectors with optimised performance.     

Measurement of liquid droplet parameters using optical fiber

The measurement of liquid droplet parameters such as size, number, concentration, viscosity, and refractive index is reported. The droplets are sprayed either from a pressure nozzle or a gas atomizing nozzle. The parameters are measured by detecting the clad mode power in the leaky ray zone of a three-region fiber by a new clad-probing technique, using normal core-clad fiber. The refractive index of the liquid is close to that of cladding. Taking the loss characteristics into account, the variation of output power with the deposition of droplets on the fiber is analyzed and compared with experimental results. The measurement sensitivity for different probing conditions is shown experimentally and verified by theoretical analysis. The change in bound power with the number of liquid droplets depositing on unclad fiber is also shown     

单模单偏振光纤基模截止波长的测量

本文给出了单模单偏振光纤基模截止波长的测量原理和测量装置，对W－型单模单偏振光纤的基模截止波长进行了测量，并将测量结果和数值计算进行了比较，它们较好的吻合一致。     

Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These coolant materials were chosen for the first in this series of measrements of the complex parameters of liquids over the entire millimeter and submillimeter wavelength range of the spectrum. The fluorocarbon coolants not reported here exhibit an order of magnitude lower loss. It is the characteristic of these liquids that the absorption coefficient increases monotonically with frequency.     

Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These two promising millimeter wave materials were found to exhibit one order of magnitude higher absorption coefficient than the common low-loss ceramics such as alumina, fused silica and beryllia. A modular, polarizing, dispersive Fourier transform spectrometer capable of operating over the range 5 mm to 0.004 mm was used to provide a continuous spectrum of the refractive index and absorption coefficient to an accuracy of five decimal places and less than 1 percent, respectively.     

Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These low loss materials were chosen for the first in this series of measurements of the complex parameters over the entire millimeter and submillimeter wavelength range of the spectrum. A modular, polarizing, dispersive Fourier transform spectrometer capable of operating over the range 5 mm to 0.004 mm was used to provide a continuous spectrum of the refractive index and absorption coefficient to an accuracy of five decimal places and less than 1 percent, respectively.     

Stress and temperature effects on optical loss increase for phosphor-doped silica fibre in the long wavelength region

Irreversible loss increase in the long-wavelength region is first observed for phosphor-doped silica fibres with silicone resin layer by applying the stress at high temperature. The loss increment becomes larger for longer wavelengths. Experimental results show that the loss increase is strongly dependent on stress and temperature.     

The measurement of self-focusing parameters using intrinsic optical damage

A new method for measuring the self-focusing parameters of transparent materials is reported. The technique consists of using lenses with different focal lengths to induce intrinsic bulk damage at low powers where catastrophic self-focusing is absent and then comparing the results to analytical calculations. Using this technique, the self-focusing parameters for sapphire are determined.     

光纤传感器在带传动参数测量中的应用

提出一种用光纤传感器测量高速旋转构件微小位移量的新方法,实现了非接触式高速、高精度的位移测量。在介绍光纤传感器测量原理的基础上,得出光强与测距之间关系式。将光强转为电压信号,建立电压商值与测距之间的拟合公式。设计V带参数测量实验台,对V带稳定运转时其在轮槽中的径向位移进行测定,进而得出V带在带轮中的轨迹,测量出滑动角的大小。针对原有V带滑动角计算公式中的不足进行优化,得出新的滑动角计算公式。对比实验结果,新公式更接近实验结果,误差更小,为V带的精确设计提供理论依据。     

Simple and highly sensitive method for wavelength measurement of low-power time-multiplexed signals using optical amplifiers

We describe a simple method for the wavelength measurement of optical signals that is easily capable of measuring a 1-nW average power optical signal with a wavelength resolution of 0.1 pm/Hz/sup 1/2/ while maintaining a large measurement range in excess of 12 nm. The system uses an erbium-doped fiber amplifier to increase the signal level before being measured with a wide-band edge filter. This technique is well suited to the measurement of low duty cycle time-multiplexed signals such as those in multiplexed fiber sensor systems. We show that the measurement of the amplified signal is improved despite the broadband nature of the amplified spontaneous emission noise. We show for the first time that the addition of an amplifier can increase the detection capabilities of the edge filter method beyond the shot noise limit of an unamplified measurement.     

Routing and wavelength assignment in optical networks

The problem of routing and wavelength assignment (RWA) is critically important for increasing the efficiency of wavelength-routed all-optical networks. Given the physical network structure and the required connections, the RWA problem is to select a suitable path and wavelength among the many possible choices for each connection so that no two paths sharing a link are assigned the same wavelength. In work to date, this problem has been formulated as a difficult integer programming problem that does not lend itself to efficient solution or insightful analysis. In this work, we propose several novel optimization problem formulations that offer the promise of radical improvements over the existing methods. We adopt a (quasi-)static view of the problem and propose new integer-linear programming formulations, which can be addressed with highly efficient linear (not integer) programming methods and yield optimal or near-optimal RWA policies. The fact that this is possible is surprising, and is the starting point for new and greatly improved methods for RWA. Aside from its intrinsic value, the quasi-static solution method can form the basis for suboptimal solution methods for the stochastic/dynamic settings.