Applications of Fibre Optic Ring Resonators Using Laser Diodes

It is demonstrated that fibre optic ring resonators are well suited for use as spectral discriminators for the measurement of spectral line width and for the stabilization of the spectral line width of external-cavity laser diodes. Although the measuring method is very simple, accuracies within - 10 and - 20 per cent were obtained in the spectral line width ranges above 1 MHz and 300 kHz, respectively. The spectral line width is stabilized by the automatic phase control of feedback light. Moreover, the operation point of the fibre optic ring resonator is stabilized by automatic frequency control of the laser. The principles, experimental results and problems are described in detail.     

Refractometric Sensors for Lab-on-a-Chip Based on Optical Ring Resonators

We demonstrate refractive index measurement of liquids using two sensor system designs, both based on microring resonators. Evanescent sensors based on microrings utilize the resonating nature of the light to dramatically decrease the required size and sample consumption volume, which are requirements of lab-on-a-chip sensor systems. The first design, which utilizes an optical microsphere, exhibits a sensitivity of 30 nm/RIU and a resulting detection limit on the order of 10^-7 RIU. The second approach is a novel design called a liquid core optical ring resonator (LCORR). This concept uses a quartz capillary as the fluidics and as the ring resonator and achieves a sensitivity of 16.1 nm/RIU. The detection limit of this system is around 5times10^-6 RIU. Both of these systems have the potential to be incorporated with advanced microfluidic systems for lab-on-a-chip applications. In particular, the LCORR combines high sensitivity, performance stability, and microfluidic compatibility, making it an excellent choice for lab-on-a-chip development     

Study of Transverse Effects in Optical Bistable Ring Resonators Using the Finite Element Method

Abstract

An extension of the finite-element/finite-difference propagation algorithm has been applied to simulate the propagation of a laser beam in a nonlinear optical bistable ring resonator. Agreement with established results has been shown, applying an inherently versatile numerical technique offering a high level of efficiency.     

Instability Thresholds in General Nonlinear Ring Resonators

Abstract

By considering a passive ring cavity with linear absorption in the dispersive limit, a unified analysis is presented for tuning-optimized minimum instability thresholds; the treatment is general, allowing consideration of arbitrary material response times, cavity tuning and finesse. In the adiabatic limit (τ → 0) the results reduce to the usual Ikeda map. The case of long medium-response time (τ → ∞) is treated in some detail in the high-finesse limit; these conditions being of particular relevance to semiconductor laser amplifiers. It is found analytically that in the high-finesse limit, both optical bistability and self-pulsing instabilities should exhibit the same low-threshold behaviour. An analytical expression is derived for the ‘instability threshold curve’, A ² B against B for minimum A ², in the mapping limit.     

Analysis and Comparison of Birefringent Fibre Ring Resonator Types

Abstract

We present a theoretical model that can be used to determine the output of fibre ring resonators made with birefringent fibre, and with different types of polarization-selective or polarization-insensitive couplers. We derive tolerances for the coupler polarization crosstalk, splice alignment, and input polarization mode purity necessary for optimum operation of each type.     

Excitation of Bound Modes in an Optical Fibre

Abstract

Simple approximate formula for the excitation of an optical fibre by a plane wave focused through a lens are presented. The formula are valid for any mode of a weakly guiding fibre, and depend only on the angle of incidence of the plane wave striking the lens and a single parameter which contains all the waveguide information. The same results apply to the case of a uniform beam exciting a fibre. The fraction of power excited in the first two modes is compared with numerical results.     

Molecular Azo Glasses as Grating Couplers and Resonators for Optical Devices

Multifunctional molecular glasses are versatile tools for organic optoelectronics. Their optical waveguide properties are of increasing interest. By using photopatterned molecular azo glass gratings, optical waves within multilayer devices can be controlled, optically excited, and brought to resonance.     

验配眼镜产品光学中心垂直互差测量结果的不确定度评定

介绍了验配眼镜产品光学中心垂直互差测量结果不确定度评定。     

Coupling Between an Accumulator and a Loop in a Mechanically Pumped Carbon Dioxide Two-Phase Loop

By means of experiment and simulation, we investigated the coupling between the accumulator and the loop in the Tracker Thermal Control System (TTCS) system, which is a typical mechanically pumped carbon dioxide two-phase loop, by studying the system behaviors under the disturbance of the temperature boundary of the condensers, and the step change of the evaporator heat load. We found that the disturbance of the loop affects the accumulator, and in turns, affects the loop itself. If the heat compensation of the accumulator is large enough, e.g., by using the accumulator heater with enough heating power and with a thermal conductance good enough between the heater and the two-phase CO₂ inside the accumulator, the loop is controllable over the disturbance. The coupling is a fundamentally important factor to be considered for the design of a stable and controllable two-phase system, such as a mechanically pumped two-phase loop.     

Investigation and Simulation of a Two-Channel Drop Filter with Tunable Double Optical Resonators

In this paper, a photonic crystal (PhC) two-channel drop filter based on two 2×2 & 2×3 ring resonators is proposed. This structure is made of Germanium rods in an air background at a two-dimensional (2D) square lattice. Refractive index is chosen in a way in which that device can be easily fabricated. The photonic crystal two-channel drop filter is composed using a horizontal waveguide and two ring resonators, which are placed symmetrically about the horizontal axis. These ring resonators operate as energy coupling and capture the electromagnetic energy propagated in bus waveguide at their resonance frequencies. The filter characteristics are calculated using 2D finite-difference time-domain (FDTD) and plane wave expansion (PWE) methods. We show a two-channel drop filter with two resonators, based on studied basic structures and achieving optimal modes for channel drop filters with one resonator. We have done this through choosing the proper radii for all rods of lattice, setting radii of coupling rods, lattice constant, and studying basic structures having different refractive indexes. Finally, we show 84 % and 100 % dropping efficiencies can be achieved at D and C ports in the communication window and 100 % in direct port. The size of this device is 14.56 μm (length)×11.96 μm (width). This small size makes it possible to use the device in multiplexer applications in future communication systems and in all-optical integrated circuits.     

检定与校准的区别

本文简单论述计量工作中检定与校准的区别。     

Squeezing of Bound Solitary Waves in a Birefringent Optical Fibre

Abstract

The coupled nonlinear Schrödinger equations in a birefringent optical fibre are derived by means of the method of path integrals. The dependence of the squeezing effect on the coupled waves is obtained with a first-order perturbation approximation, considering zero-dispersion, normal and abnormal dispersion.     

环形腔中非线性周期结构介质的双稳态和光限

研究了环腔中的非线性周期结构介质的光学双稳态和光限现象，建立了输入光强与输出光强关系的表达式。理论上给出了临界入射光强低达１０＾７Ｗ／ｃｍ＾２的光学双的条件和非常有效的限光作用的条件。     

Polarization Beam Splitting in Optical Fibre Couplers Due to Form Birefringence

Abstract

Polarization dependent corrections to the scalar coupling coefficients of the fundamental modes on two identical optical fibres are calculated from scalar supermode fields corrected up to first order in weak coupling. The method applies to arbitrary refractive-index profiles.     

Chromatic Modulation for Optical Fibre Sensing Electromagnetic and Speckle Noise Analysis

Abstract

Changes in the chromaticity of the transmitted electromagnetic field in an optical fibre are considered. An electromagnetic analysis that predicts the radial dependence of the chromaticity at the exit is presented and coupled to a speckle noise analysis which provides an estimate of the error. Theoretical predictions are compared with experimental results and good agreement between the two is demonstrated. The results can be useful in the design of optical fibre sensors which use the chromatic modulation method.     

SDH传输系统光接口输出功率的测量不确定度

本文介绍了依据YD/T 767-95《同步数字系列设备和系统的光接口技术要求》和YDN 105-1998《同步数字体系（SDH）复用终端设备测试方法》,按JJF1059-1999《测量不确定度评定与表示》对SDH传输系统光接口输出功率的测量结果不确定度的评定方法.     

嘧啶环取代二乙炔的光限幅特性

应用Ｎｄ：ＹＡＧ脉冲激光研究了新型有机材料嘧啶环取代二乙炔的光限幅特性，其优点是线性透射率比较高，限幅阈值低，有望用于复合型限幅器的第一级。     

Plastic Optical Fibre Sensors for Environmental Monitoring: Biofouling and Strain Applications

Abstract: Two long-term environmental monitoring plastic optical fibre (POF) sensors are described, using light intensity modulation. An evanescent field biofouling sensor was developed and characterised with sensitivity ±0.007 refractive index units or 0.5% below n  = 1.4 and ±0.002 refractive index units or 0.15% above n  = 1.4. A tapered POF was developed and tested as a strain sensor, which demonstrated a significant proportion of excellent linearity and exhibited good agreement with measured strain values. The POF strain sensor appeared to be well-behaved in that it showed little data scatter and was able to monitor strains up to 1.4% without failure. These two applications clearly demonstrate the potential POF sensors have for cheap, on-line continuous environmental monitoring.     

Fabrication and Sensing Performance of Smart Composite Structures Using Optical Fibre Sensors

This paper determines the performance of Fibre Bragg Grating (FBG) sensors for strain sensing applications in carbon fibre composite materials. Carbon fibre laminates in either cross-plied or quasiisotropic stacking sequences were fabricated using T300/Hexcel 914 prepregs. The FBG optical sensors were either surface attached, or embedded within laminates. The sensor orientation was aligned either parallel or transverse to the adjacent carbon fibre layers. The composite structures with integrated FBG sensors were subjected to static tensile loading. A scanning fibre Fabry-Perot filter was used to monitor the reflected Bragg wavelengths. The optical sensor embedded between two 90° carbon fibre plies shows a high sensitivity to multi-site cracking formed in the transverse plies. The embedding in 90° plies seems to change the local stress distributions and to become a source of crack initiation. Efficient stress transfer from the host materials to the sensors is dependent upon incorporation methods, the thickness of the adhesive layers, and the location of the sensors.     

Fabrication and Sensing Performance of Smart Composite Structures Using Optical Fibre Sensors

This paper determines the performance of Fibre Bragg Grating (FBG) sensors for strain sensing applications in carbon fibre composite materials. Carbon fibre laminates in either cross-plied or quasiisotropic stacking sequences were fabricated using T300/Hexcel 914 prepregs. The FBG optical sensors were either surface attached, or embedded within laminates. The sensor orientation was aligned either parallel or transverse to the adjacent carbon fibre layers. The composite structures with integrated FBG sensors were subjected to static tensile loading. A scanning fibre Fabry-Perot filter was used to monitor the reflected Bragg wavelengths. The optical sensor embedded between two 90° carbon fibre plies shows a high sensitivity to multi-site cracking formed in the transverse plies. The embedding in 90° plies seems to change the local stress distributions and to become a source of crack initiation. Efficient stress transfer from the host materials to the sensors is dependent upon incorporation methods, the thickness of the adhesive layers, and the location of the sensors.