Metallic waveguide mirrors in polymer film waveguides

A technology for the fabrication of metallic waveguide mirrors is developed. Plane and curved waveguide mirrors, the latter acting in the same way as cylindrical lenses, are realized in benzocyclobutene (BCB) film waveguides. The waveguide mirror structure is dry-etched into the BCB film waveguide. To enhance the reflectivity of the waveguide mirrors, the waveguide edge is metallized. The BCB film waveguide mirrors are characterized with respect to waveguide attenuation and mirror reflectivity. The waveguide attenuation of the processed BCB waveguide is 0.5 dB/cm. Ag-coated BCB waveguide mirrors show a reflectivity of 71%. The efficiency of total internal reflection (TIR, i.e. in the case without metallization) at the dry-etched waveguide edge is 74%. As an application of the BCB waveguide mirrors a hybrid integrated optical module for Fourier-optical transverse mode selection in broad area lasers (BAL) is proposed. Received: 16 May 2001 / Published online: 23 October 2001     

T型缝隙结构表面等离子波导的基本特性研究

An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton （CPP） waveguide. This paper presents research on the basic properties of this waveguide using the Finite Difference Time Domain（FDTD） method. The relationship between transmission power and structure of the waveguide is investigated. The simulation results show that the subwavelength trapezoidal CPP waveguide is superior to the rectangle CPP waveguide for controlling SPP radiation loss and enhancing the transmitted power. As a result, if the rectangle CPP waveguide is replaced by a trapezoidal CPP waveguide in certain integrated optical devices, their performance may be improved.     

T型缝隙结构表面等离子波导的基本特性研究(英文)

An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton(CPP) waveguide. This paper presents research on the basic properties of this waveguide using the Finite Difference Time Domain(FDTD) method. The relationship between transmission power and structure of the waveguide is investigated. The simulation results show that the subwavelength trapezoidal CPP waveguide is superior to the rectangle CPP waveguide for controlling SPP radiation loss and enhancing the transmitt...     

对称平面单轴晶体金属波导的模式场(1)

由于平面各向异性介质金属波导的重要应用,本文讨论了光在对称平面单轴晶体金属波导(波导层是单轴晶体,两个波导界面均为金属)内的传输特性.对于晶体光轴位于波导界面法方向与传输方向构成的平面内的特殊波导结构,利用麦克斯韦方程组并结合单轴晶体的性质,精确解出了波导模式场.结果表明:1)此种特殊结构波导内存在横电波(TE)和横磁波(TM);2)TM波的坡印廷矢量与波矢方向不在一条直线上;3)波导层为负单轴晶体时波导主模是TE波主模,而波导层为正单轴晶体时波导主模是TM波主模.     

Radiation properties of ICRF waveguide couplers

The radiation spectra of a dielectric-filled waveguide (DWG) and a folded waveguide (FWG) antenna in the ion cyclotron range of frequencies are evaluated for tokamaks with the waveguide codes, which model the coupling of the waveguide modes to the plasma waves with outward radiating boundary conditions. The codes provide a self-consistent calculation of the fields across the waveguide apertures for various antenna phasings taking into account a complete set of waveguide eigenmodes including the reflected modes and, in the case of DWG, an arbitrary orientation of the antenna to the plasma magnetic field. In the studied cases, the spectra are found to be well described by a model which is based on a simplified wave field pattern determined by the antenna aperture geometry. Comparison to the corresponding loop antenna is carried out     

Double optical waveguide in Cu-doped KNSBN crystal formed by MeV boron ion implantation

We reported for what is to be believed the first time a double optical waveguide in a Cu-doped potassium sodium strontium barium niobate (KNSBN) crystal formed by double boron ion implantation. The energy and dose of B⁺ and B³⁺ ions were (3+6) MeV and (2+2)×10¹⁴ ions/cm², respectively. The refractive index profile of the waveguide showed a double-barrier confined shape, which suggested the formation of a two-layer waveguide structure. The two waveguide layers were with thickness of 2.6 and 2 μm, respectively, which was in a good agreement with the parameters obtained from transport and range of ions in matter 98 (TRIM) code simulation. The nuclear energy loss distribution of the MeV B ions implanted into this crystal had a similar shape to that of the waveguide index profile, which means an inherent relationship between the waveguide formation and the energetic energy deposition.     

Planar waveguides in neodymium-doped calcium niobium gallium garnet crystals produced by proton implantation

In this work, the fabrication and optical properties of a planar waveguide in a neodymium-doped calcium niobium gallium garnet(Nd:CNGG) crystal are reported. The waveguide is produced by proton(H~+) implantation at 480 ke V and a fluence of 1.0×10~(17) ions/cm~2. The prism-coupling measurement is performed to obtain the dark mode of the waveguide at a wavelength of 632.8nm. The reflectivity calculation method(RCM) is used to reconstruct the refractive index profile. The finite-difference beam propagation method(FD-BPM) is employed to calculate the guided mode profile of the waveguide.The stopping and range of ions in matter 2010(SRIM 2010) code is used to simulate the damage profile induced by the ion implantation. The experimental and theoretical results indicate that the waveguide can confine the light propagation.     

Composite optical waveguide composed of a tapered film of bromothymol blue evaporated onto a potassium ion-exchanged waveguide and its application as a guided wave absorption-based ammonia-gas sensor

For what is the first time to our knowledge, we have successfully evaporated a tapered film of bromothymol blue (BTB) onto a potassium ion-exchanged (PIE) waveguide to form a composite optical waveguide (COWG) for trace-ammonia detection. The BTB film has a high refractive index (1.69) and a smooth surface and is transparent to a 633-nm laser beam in air. In the COWG structure, the BTB film serves as a single-mode waveguide, and adiabatic transition of the TE(0) mode was realized between the BTB waveguide and the PIE waveguide with both BTB tapers. In the presence of ammonia, the BTB film changes color from yellow to blue, which causes absorption of the 633-nm guided wave. Our experimental results demonstrate that such a guided wave absorption-based ammonia-gas sensor is much more sensitive than one based on evanescent-wave absorption. A detection limit of part in 10(9) of ammonia has been realized for a BTB film-PIE glass COWG.     

A proposal for the generation of optical frequency comb in temperature insensitive microcavity

We numerically simulate the generation of an optical frequency comb(OFC) in a microring based on the traditional Si_3N_4 strip waveguide and a temperature compensated slot waveguide.The results show that OFCs are susceptible to temperature with strip waveguide while they can keep stable when temperature changes 10 Kin either low-Q(10~5) or highQ(10~6) microcavity with the well-designed slot waveguide,which has great superiority in practical applications where the temperature drift of the cavity due to the intense pump or surrounding change is unavoidable.     

Dispersion compensation based on the combination of coupled ring resonator and photonic crystal structures

An optical delay line of coupled resonator optical waveguide(CROW) compensated by photonic crystal waveguide(PhCW) is proposed. In the structure,etching the periodic holes around the waveguide of the ring resonator waveguide does not increase the size of the CROW. Theoretical studies and numerical models indicate that through careful design,CROW and PhCW exhibit different group velocity dispersion(GVD) properties at a certain frequency range. Optical signal can not only be compensated in terms of GVD,but can also be delayed with longer time period. Due to the propagation mode mismatch of the two structures,optical loss becomes inevitable.     

Stratified waveguide grating coupler for normal fiber incidence

We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that approximately 72% coupling efficiency is possible for fiber (core size of 8.3 microm and delta=0.36%) to slab waveguide (1.2-microm core and delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.     

Spatial vector solitons consisting of counterpropagating fields

We present the experimental observation of a spatial vector soliton formed by counterpropagation of coherent optical fields. This is to our knowledge the first observation of a vector soliton in which the induced waveguide (potential) is periodic in the propagation direction. This vector soliton induces a waveguide and a thick grating within the waveguide, which can be used as a tunable optical waveguide filter.     

Dual-Core Leaky Waveguide-Based Filters for Erbium-Doped Waveguide Amplifier

Abstract

This article gives the design of a gain-flattening filter for an erbium-doped waveguide amplifier using a dual-core resonant leaky waveguide. The spectral variation of leakage loss of the waveguide has been used for gain equalization of the erbium-doped waveguide amplifier in the conventional (C) band. Leakage loss of the structure has been calculated by using the transfer matrix method. Numerical simulation results show a 17.5-dB gain with a gain excursion of ±1.35 dB in the C-band (1,526 nm–1,566 nm) of a typical erbium-doped waveguide amplifier. The study should be useful in designing integrated optic gain-flattening filters.     

Wave propagation in parallel-plate waveguides filled with nonlinear left-handed material

A theoretical investigation of field components for transverse electric mode in the parallel-plate waveguides has been studied. In this analysis two different types of waveguide structures have been discussed, i.e., (a) normal good/perfect conducting parallel-plate waveguide filled with nonlinear left-handed material and (b) high-temperature-superconducting parallel-plate waveguide filled with nonlinear left-handed material. The dispersion relations of transverse electric mode have also been discussed for these two types of waveguide structures.     

Analysis of Planar Dielectric Waveguide with Mirror-Conjugate Chiralities in the Core and the Cladding

The propagation characteristics of a planar waveguide with mirror-conjugate chiralities filled in the core and the cladding (mirror-conjugate chirality waveguide) are presented. The effects of chirality on cutoff, dispersion and field distribution characteristics of the waveguide are studied. The results show that the waveguide with desired features can be made by appropriately selecting the chiralities of the core and the cladding, because the core chirality and cladding chirality have different influences on waveguide propagation characteristics.     

Field Patterns of the TE Modes in Ridge-Trough Waveguide

A single-ridge waveguide with a symmetrical longitudinal trough, designated as a ridge-trough waveguide has been used as a transition in a V-band (50-75 GHz) wafer probe recently. In this paper, the field patterns for the dominant TE mode and the first higher TE mode in ridge-trough waveguide with different configurations are presented by finite element method. The field patterns in this paper have important values for us to understand the transmission characteristics of ridge-trough waveguide, and will be of practical significance in designing ridge-trough waveguide components in microwave and millimeter wave engineering.     

The investigation of the photonic waveguide structure made of silicon carbide by means of the method of the singular integral equations

Here we present the analyses of the open (without a metal screen) ridged and photonic waveguide structures by means of the electrodynamical rigorous method of the Singular Integral Equations (SIE). The waveguides are made of a lossy silicon carbide (SiC) material. We have discovered peculiarities of the dispersion characteristics. We have found the numerical solutions to the complex wave equations. The dispersion characteristics of both waveguide structures are numerically analyzed and compared with each other. It was found that the losses of modes propagating in the waveguide structure with air openings (channels) are smaller than the losses in the waveguide structure without air openings. We came to the conclusion that it is possible to optimize the dispersion characteristics by adding openings of different shapes and sizes into the waveguide structures.     

Optical surface modes of photonic crystals for dual-polarization waveguide

In this study, the design of a polarization-independent (dual-polarization) waveguide is presented by utilizing surface modes of photonic crystals. The waveguide structure operates in a frequency interval that is commonly shared by both transverse-electric (TE) and transverse-magnetic (TM) polarizations. The numerical calculations based on plane wave expansion and finite-difference time-domain methods are carried out to design and demonstrate a surface mode waveguide that provides confinement and guiding for both TE and TM modes. Once the relevant modes are properly excited, the high transmission efficiency of the photonic crystal surface waveguide is ensured. The demand to have polarization-insensitive devices makes our proposed design an important component for the photonic integrated circuit applications. Finally, we also propose a broadband surface mode photonic crystal waveguide with a bandwidth value of 28% for only TE polarization.     

A novel wavelength dispersive device with a dispersive element based on staircase-like straight and parallel arrayed waveguides

We propose a new type of arrayed waveguide grating (AWG) multiplexer/demultiplexer based on modified group refractive index. This device is composed by an array of straight and parallel waveguides of equal length and each waveguide consist of two sections with different width. The length of the two sections are changed from a waveguide to the adjacent one following a linear dependence resulting in a wavelength dispersive waveguide array. An example of the device design for silicon-on-insulator (SOI) platform is provided and numerical simulations have been carried out for various arrayed waveguide parameters. We demonstrate that the group index modification can be used for tailoring device dispersion properties, and that it can also result in new dispersion characteristics predicted numerically not observed in conventional AWGs. Additional advantages are that the demultiplexer does not necessarily require bending waveguide sections as in a conventional AWG (de)multiplexers, and thus yields highly compact devices with potentially very low insertion loss. Channel spacing of 1 nm have been predicted for sub-micron waveguides sizes. In this paper it is also proposed a novel wavefront converter based on waveguide array lens-like element with waveguides broadened sections. Numerical results for different input/output geometries are analized.