Integrated hollow waveguides with arch-shaped cores

An optical waveguide is described that has a hollow arch-shaped core. Optical confinement for this structure is based on the antiresonant reflecting optical waveguide principle. The waveguides are built on a silicon substrate using a sacrificial etch technique with reflowed photoresist serving as the sacrificial material and producing the core's arch shape. Investigations of fabrication parameters are reported that allow for predicting a final arch-shaped geometry based on initial photoresist width and thickness. Optical mode guiding is demonstrated in an arch-shaped waveguide with a liquid core.     

集成光学调制器在光纤陀螺中的调制特性研究

对高精度光纤陀螺(零漂>0.01(°)/h)中的核心光学器件——铌酸锂集成光学调制器在光纤陀螺中的调制特性及系统测试方法进行了探讨,对其应用及与光路其他各部分配合的技术进行了理论分析和实验研究。与此同时,对该器件在光纤陀螺系统中的特性研究建立了通用的测试系统。文中提出了集成光学调制器与系统匹配的问题。研究结果表明:铌酸锂集成光学调制器的光、电特性以及其电特性与系统的匹配对陀螺的性能发挥着至关重要的作用。     

Y-branch waveguides with stabilized splitting ratio designed by wavefront matching method

We designed optical Y-branch waveguides with a stabilized splitting ratio by using a new design approach based on the wavefront matching method. The designed Y-branches were fabricated using silica-based planar lightwave circuit technology. We suppressed any variation in the splitting ratio of the Y-branch experimentally and obtained excess losses of <0.35 dB over a wide wavelength range of 1.3-1.7 /spl mu/m.     

Integrated optic frequency shifter modulator

The letter describes a novel integrated optic configuration to impose a frequency shift on laser light. The new device is simple to fabricate and has a very broad bandwidth extending from kilohertz to hundreds of megahertz. It Converts over 40% of the input optical power to the required sideband.     

Integrated optical ultrashort-pulse picker with high extinction ratio

An integrated optical Mach-Zehnder modulator in lithium niobate was used for pulse picking of a 140 fs laser oscillator at 1064 nm with 76 MHz repetition rate. A maximum extinction ratio of about 1000:1 was demonstrated at a peak power of about 120 W.     

Integrated optic electrooptic modulator electrode analysis

Integrated optical (IO) switches and modulators are based on the electrooptic effect obtained by applying a voltage between electrodes fabricated on the surface of a crystal (for example, LiNbO3). In this paper, we calculate the change in the optical propagation constant in single modeZ-cut LiNbO3:Ti-diffused waveguides for a variety of electrode configurations. These calculations are compared to experimental data from IO devices. The calculations predict the observed variations in switching voltage with wavelength and electrode separation.     

环形耦合谐振腔光波导的耦合率对光学延时线的影响

本文根据Bloch理论研究了耦合谐振腔光波导(CROW)的群速度、延迟时间及存储容量随耦合率的变化规律。结果表明,耦合谐振腔光波导(CROW)的群速度、延迟时间及存储容量随着耦合率的增大而降低,而色散随耦合率的增大而增大。还运用传输矩阵的方法,研究了环形耦合谐振腔透过率随耦合率的变化规律。在不考虑损耗的情况下,耦合率对透过率无影响,考虑损耗时,透过率则随耦合串的减小而减小。对衰减系数为0.995,耦合率为0,235情况下的CROW进行模拟。模拟结果显示,当CROW中含64个谐振腔时,延迟时间能达到100ps,透过率可达到-27dB,可以满足实际应用需要。     

Integrated optic devices for microwave applications

Integrated optic devices designed for use in microwave applications are reviewed, and the prospects for these technologies are discussed. The interaction of lightwave and microwave signals, especially the modulation of light at microwave frequencies, is briefly summarized, and features of integrated optic devices are pointed out     

Integrated optic series and multibranch interferometers

Series and multibranch interferometer filters are analyzed and demonstrated. The response of the interferometers for various configurations is estimated. Measured results are presented for two series interferometers and a three branch interferometer realized with Ti indiffused waveguides in Y-cut LiNbO3.     

Sputtered silica waveguides with an embedded three-dimensional structure

Single-mode sputtered silica waveguides (SS guides) are fabricated by filling channels of 8-μm width in a silica substrate with core silica material and embedding with a cladding layer. Silica deposition process is carried out by bias sputtering. The measured waveguide loss was 1.2 dB/cm. The change of cross-sectional profile in the sputtering process on the channel is analyzed with the result in good agreement with experiments. The optimum sputtering condition for filling the channel is elucidated. The method is applied to embedding gratings fabricated on the silica substrate.     

Quasi-TEM analysis of coplanar waveguides with an inhomogeneoussemiconductor substrate

In this paper, we study the normalized wavelength and attenuation constant of coplanar waveguides with a finite metal thickness. The substrate is a lossy inhomogeneous insulator-semiconductor, and the conductor is assumed perfect. Electroquasi-static approximation is used to derive a Laplace's equation with a complex permittivity in each inhomogeneous layer, from which the eigenmodes are obtained. Proper boundary conditions between contiguous layers are applied to calculate the charge distribution on the center conductor. The effects of the insulator depth and semiconductor conductivity on the normalized wavelength and attenuation constant are analyzed     

Integrated optic polymeric components fabricated withmicrostructured strip-off covers

Fabrication of integrated optic polymeric components by moulding waveguide and fibre alignment grooves to a substrate in a one-step process, and subsequently filling the waveguide grooves by means of a microstructured strip-off cover which is later removed, is presented. The latest measurement results on waveguide attenuation, coupling losses owing to passive fibre-waveguide coupling and excess loss values are given     

Optical waveguides with low pulse dispersion over an extended spectral range

A class of index profiles is described which can be used to minimise pulse dispersion over an extended range of wavelengths or at several different wavelengths. These profiles are compatible with standard waveguide compositions.     

Performance of an array of circular waveguides with strip-loadeddielectric hard walls

An infinite planar periodic antenna array of radiating open-ended circular waveguides is considered. The conducting waveguide walls are covered with dielectric layers loaded with longitudinal conducting strips for providing the hard wall boundary condition. Analysis of the array is carried out by the mode-matching method. The waveguide modes involved in the method are calculated by using the asymptotic strip boundary condition. It is shown that they are split into an independent subsystem of TE modes for the whole cross section and two independent subsystems of TM modes: one is for the central region and another is for the layer region. The calculations show that the operation of the hard waveguides in an array with small element spacing is similar to that of the multimode smooth wall waveguides completely filled with dielectric. For large diameters and element spacing, the hard waveguides have significant advantages over the smooth ones. It is shown that unlike an individual hard waveguide, the aperture efficiency of such a waveguide in the array has a nonmonotonic dependence on the waveguide radius. The results characterizing the behavior of the aperture efficiency and cross-polarization level in a frequency band as well as the contribution of certain waveguide modes in the reflected power are presented and discussed. The examples of the element patterns corresponding to minimal cross polarization are also given     

Planar optical waveguides with arbitrary index profile: an accuratemethod of analysis

We present here an improvement of the existing modified Airy function (MAF) method. The results of our study show that the improvement gives extremely accurate propagation constants and also the modal fields for planar waveguides with arbitrary index profile     

Integrated optic strip waveguide phase modulator driven by a SAW

Single-mode integrated optic strip waveguide phase modulators driven by a surface acoustic wave (SAW) are investigated theoretically and experimentally. Evaluating the overlap integral, a good agreement is obtained between measured and theoretical results. Measurements were performed onZY-LiNbO3(z-cut crystal,y-propagating SAW) between 20 MHz and 580 MHz atlambda_{0} = 0.85 mum optical wavelength using Titanium indiffused waveguides. At 9-mW SAW power in an interaction length of 4 mm, optical phase shifts are measured to be 0.32 and 0.112 for TM and TE polarization, respectively, at 21.5 MHz.     

Integrated optical polariser on LiNbO3:Ti channel waveguides using proton exchange

A polariser on a Ti:LiNbO3 channel waveguide has been realised using a double fabrication process (Ti indiffusion and proton exchange). A region is created where the extraordinary polarisation experiences a leaky propagation leading to an extinction ratio of 30 dB and excess loss of about 1 dB.     

The performance of an iris-loaded planar phased-array antenna of rectangular waveguides with an external dielectric sheet

A new method for calculating the performance of an iris-loaded planar phased-array antenna of rectangular waveguides is presented. The method is based upon the expansion of the tangential electric aperture field in terms of judiciously chosen functions. Also, the influence of a dielectric sheet in front of an antenna the apertures of which are loaded with inductive irises is investigated. In the experiments, a sheet with a low relative permittivity (epsilon_{r} = 2.3orepsilon_{r} = 3.5) is spaced in front of a space-fed planar antenna of some 850 radiating elements, and the total transmitted power of the antenna is measured as a function of frequency and scan angle. The results indicate, that both in theory and in practice, an excellent match can be achieved with a polythene sheet (epsilon_{r} = 2.3) or a Perspex sheet (epsilon_{r} = 3.5).     

Circular waveguides with anisotropic walls

First, the wave propagation in circular waveguides with the boundary condition E? = H? = 0 is investigated, and the use of these guides for producing circularly polarised waves is described. Secondly, a similar investigation is made for corrugated guides. Their propagation characteristics are compared.