Erratum to “Investigation of Insertion Loss in Inkjet-Printed Coplanar Waveguide Based on Drying Temperature”

An approach to obtain effective control of insertion loss (IL) in wideband substrate-integrated waveguide (SIW) band-pass filter with several tapered iris configurations is presented in this paper. Several iris configurations and iris parameters have been minutely studied and effective postulates have been provided for accurate design of filters with low IL throughout the transmission bandwidth. Basic structure is designed over a substrate with dielectric constant 3.2 and material thickness of 30 mils. The structures are then successfully modified into a band-pass filter with its pass band in Ku bands with minimal IL using waveguide iris method. The technique effectively serves the purpose to achieve greater control over the IL and isolation. Maximum IL of 2 dB is reduced by 1.5 dB and close to 0.5 dB IL is obtained in the final configuration using the tapering technique. Proposed techniques are supported with theoretical explanations. All designs are fabricated, and measured results are found to validate the concept produced in this paper. The study provides a direct solution to the SIW Iris filter design engineers considering all major parameters necessary for industrial/scientific productions. Cite this article as: J. Kundu Paul, S. Moitra and P. Sarathee Bhowmik, "Control of insertion loss in substrate-integrated waveguide (SIW) band-pass filter using new tapered waveguide iris technique," Electrica, 24(1), 256-264, 2024.

In this paper, new and fast analytical formulations have been presented for conductor loss calculations of elliptical (ECPW) and cylindrical coplanar waveguide (CCPW) with finite conductor thickness. These expressions are derived using conformal mapping techniques (CMT) and the validity of them is established by comparing the numerical results in the literature. These comparisons indicate that for the same conductor thickness the conductor losses of elliptical and cylindrical coplanar waveguide are higher than the conductor losses of coplanar waveguide presented in [1]. Calculation method developed in this study is an extension of the approximate technique proposed by Ghione [1].

In the maturing field of silicon photonics, advances continue in both design and process improvements. Waveguide propagation loss is strongly affected by sidewall roughness, and so for fabrication using e-beam lithography, loss is influenced by e-beam writing parameters. Here, the authors look specifically at fracturing strategies in data preparation for e-beam lithography, and find significant reduction in waveguide loss by utilizing advanced fracturing options. For our evaluation, the authors fabricate optical waveguides using a well-characterized, highly stable baseline fabrication process with hydrogen silsesquioxane resist exposed by a 100 kV electron beam, a high-contrast tetramethyl-ammonium hydroxide develop, and a Cl2 inductively coupled plasma etch. Using surface grating couplers for input and output, automated optical measurements are made by scanning input light in the region of the design wavelength of 1550 nm and measuring optical output power. The authors use a design cell containing grating couplers and both straight and curved waveguides with a range of lengths. The authors find a significant reduction in grating coupler insertion loss and waveguide loss along with increased uniformity by leveraging a new fracturing strategy implemented in the beamer pattern data processing software from GenISys, GmbH. Single line edge smoothing is an exposure strategy in which all feature edges are traced using a single-line shape (sometimes referred to as a single-pass line) while the bulk of the shape is then exposed with trapezoidal beam filling. The insertion loss for grating couplers written using single line edge smoothing shows a significant loss reduction of 1.2 dB as well as greatly improved uniformity. Both straight and curved waveguide losses were also reduced by use of single line edge smoothing, by 0.7 and 1.1 dB/cm, respectively. Here, the authors will discuss the likely mechanisms of this improvement as well as present additional device data using these new fracturing methods which represent a significant, incremental improvement in performance of optical waveguides written by e-beam lithography.

This letter explores the dc isolation and radio frequency (RF) dissipation loss of coplanar waveguide (CPW) lines of H/sup +/ and Fe/sup +/ ion bombarded GaAs multi conductive epitaxial layers. It is demonstrated that although a sheet resistivity as high as 10/sup 8/ /spl Omega/sq has been achieved by ion bombardment, showing excellent dc isolation, the RF dissipation loss of gold metallized CPW lines on the bombarded multi conductive epitaxial layers are higher than that on a semi-insulating GaAs substrate, especially at higher frequencies (0.5 dB/cm higher at 50 GHz). This is probably caused by deep level trappings due to the ion bombardment.

Coplanar waveguides on silicon substrate were simulated. Using MEMS (micro-electro-mechanical system) technology, the V-shaped and W-shaped groove coplanar waveguides were implemented on silicon substrate, and its characteristic impedance was 30Ω, 50Ω, 75Ω and 100Ω respectively. In addition, the characteristic impedance of coplanar waveguide (CPW) was analyzed, and the conclusion was used to guide the design of MEMS CPW. According to the measurement results, insertion loss of coplanar waveguides was below 1dB/mm. If it is fabricated with lower resistivity metal, the insertion loss will be decreased.

In recent years, advances in material science for high-frequency electronics have generated novel materials that offer superior performance. Additive manufacturing (AM) has expanded the frontiers of microwave material manufacturing going beyond flat geometries and unique properties such as graded permittivity materials. Accurate electromagnetic (EM) material characterization for AM materials remains challenging given the printing volume constraints for manufacturing processes, as traditional EM property extraction techniques often require electrically large samples. Furthermore, loss extraction techniques typically cannot differentiate dielectric and conductor losses in waveguides. This paper presents a novel conformal mapping-based characterization technique using coplanar waveguides (CPW) with air pockets that allows for dielectric permittivity and dielectric loss extraction. The underlying principle of the techniques is to use a set of CPWs with different air slot depths to extract the loss behavior as a function of the slot depth. A new loss-slot rate metric is introduced to decouple the dielectric and conductor losses in the structure. The theoretical foundation of the technique is used to develop a physical-mathematical model for dielectric property extraction that is verified with simulations and experiments for materials with permittivity in the range 2.33–29, and loss tangents of 0.02–0.055. The average error for the equivalent capacitance of the CPW with air pockets (CPW-AP) between the presented model and simulated or measured data is 2.4% for all the studied cases. The experimental confirmation is performed with traditionally manufactured FR-4 and additively manufactured yttria-stabilized zirconia (YSZ) dielectrics up to 10 GHz.

Signal propagation delays dominate over gate delays in the ever-shrinking ultra large scale integrated (ULSI) circuits. Consequently, silicon-based monolithic optoelectronic circuits (SMOE) with their light speed signal propagation can provide unique advantages for future generations of microprocessors. For such SMOE circuits, we need optical interconnects compatible with silicon technology. Strip waveguides consisting of polycrystalline silicon (polySi) clad with SiO2 offer excellent optical confinement and ease of fabrication that are ideal for such interconnect applications. One major challenge with using this material system, however, is its insertion loss. In this paper we provide techniques for minimizing optical transmission losses in polySi strip waveguides. Our previous work using polySi strip waveguides, showed an optical transmission loss of 15 dB/cm at λ=1.55 µm, which is a communication wavelength of choice in optical fibers because it represents an absorption minimum. Similar measurements in crystalline silicon strip waveguides1 yielded transmission losses of less than 1 dB/cm. Hitherto, in decreasing loss from 77 dB/cm to 15 dB/cm, we had minimized loss from surface scattering by improving the film surface morphology, and decreased bulk absorption with hydrogen passivation. In this paper we report a further reduction in the residual bulk loss from 15 dB/cm to 9 dB/cm. By experimenting with different waveguide core dimensions, we find that the contribution of bulk loss towards net transmission loss decreases with waveguide core thickness. Additionally, high temperature treatment provides strain relief in the polySi, decreasing transmission loss. Annealing in an oxygen ambient is not recommended because it always increases transmission loss. Hydrogen passivation improves transmission, attributable to passivation of light-absorbing dangling bond defect sites present at polySi grain boundaries. Together, these methods have resulted in the lowest measured loss value of 9 dB/cm at λ=1.55 µm. Since integrated SiGe and Ge photodetectors are more efficient at shorter wavelengths like λ=1.32 µm, transmission loss is also measured at λ=1.32 µm. Losses at the two wavelengths (1.32 µm and 1.55 µm) are similar when defects and stress in the waveguides are minimized.

We present modeling and simulations of graphene coplanar waveguide (GCPW) under the frequency up to 50 GHz. Our simulation results show that the dimensions of GCPW greatly influence its insertion loss. In addition, different graphene layer numbers and structures of graphene-metal contact were also considered. We show that the usage of few-layer graphene and end-contact structure is able to decrease the insertion loss, which helps improve the radio-frequency performance of graphene coplanar waveguide.

This paper, for the first time, presents successful integration of a W-band antenna with an organically flip-chip packaged silicon-germanium (SiGe) low-noise amplifier (LNA). The successful integration requires an optimized flip-chip interconnect. The interconnect performance was optimized by modeling and characterizing the flip-chip transition on a low-loss liquid crystal polymer organic substrate. When the loss of coplanar waveguide (CPW) lines is included, an insertion loss of 0.6 dB per flip-chip-interconnect is measured. If the loss of CPW lines is de-embedded, 0.25 dB of insertion loss is observed. This kind of low-loss flip-chip interconnect is essential for good performance of W-band modules. The module, which we present in this paper, consists of an end-fire Yagi-Uda antenna integrated with an SiGe BiCMOS LNA. The module is 3 mm × 1.9 mm and consumes only 19.2 mW of dc power. We present passive and active E- and H-plane radiation pattern measurements at 87, 90, and 94 GHz. Passive and active antennas both showed a 10-dB bandwidth of 10 GHz. The peak gain of passive and active antennas was 5.2 dBi at 90 GHz and 21.2 dBi at 93 GHz, respectively. The measurements match well with the simulated results.

We have fabricated a polymeric waveguide by using a hot embossing technique and have investigated its propagation loss. The replication of waveguide channels through the use of a hot embossing technique is of interest as a single-step process that could deliver surface roughnesses far smaller than the wavelength. We have evaluated experimentally that the sidewall roughness has a dominant effect on insertion losses of the multimode polymeric waveguide. The propagation loss of the waveguide decreased dramatically upon decreasing the sidewall roughness of the channel. We have confirmed that the preparation of waveguides having nanometer-scale sidewall roughness and 0.1 dB/cm propagation loss is possible when using the hot embossing technique.

In this paper, we describe the cost-effective and simplified fabrication of an index modulation type buried waveguide using laser direct writing. Our studies have a potential of manufacturing waveguides on an uneven surface and a large area because there is no need for photo-mask, etching and development processes. We used organic-inorganic hybrid materials (HYBRIMER) for the fabrication of the waveguides, which have a high transparency from a visible region to an infrared region. We exposed the core layer (HYBRIMER) to a focused laser beam after a one-step spin coating process on a buffer layer. The silicon oxide was used as a buffer layer. The refractive index of the HYBRIMER film is increased by exposure from a laser beam. Therefore, the refractive index of the exposed region is higher than that of the unexposed region, which forms the index modulation type waveguide without an etching process. The fabricated waveguide channels were baked at 120 °C during 3hrs for stabilization of the organic and inorganic networks. The laser direct writing apparatus was used to produce the pattern of waveguide channels. This system consists of a He-Cd laser radiating 325nm beam, high-resolution computer-controlled translation stages and a video camera that images the sample onto a monitor. The pattern of the waveguide channel was written using various writing speeds to optimize the writing condition. The core section of optimized waveguides was a rectangular shape and the core dimension was 7μm wide and 8μm high. The refractive index is increased from 1.495 to 1.5 after exposure. The difference of the refractive index between the core and cladding was approximately 0.33%. The insertion loss of the waveguides was measured by cut-back method using a single-mode fiber as an input tip, a multimode fiber (50 μm GI) as an output tip, and a 1310nm wavelength laser light source. The insertion loss shows a linear relationship with the length of the waveguide. The propagation loss of the buried waveguide was approximately 0.3dB/cm at a wavelength of 1310nm.

Ion exchanged glass waveguide components can perform many functions needed in optical communications, but will find a use in communications networks only if insertion losses are low enough. Exchanged guides have been made with low optical propagation loss, and channel guides with excellent coupling to optical fiber have been made.|1] In some cases, however, we require direct coupling to semiconductor lasers, which have much smaller mode size than fibers. A small mode size also serves to minimize losses in waveguide bends.

In this paper, a 400-GHz silicon micromachined elliptic cavity waveguide filter with two transmission zeros on both sides of the passband is presented. The filter is cascaded by two elliptic cavities which are operating at quasi- ${\rm TM}_{110}$ mode. Each elliptic cavity can introduce a transmission zero near the passband of the filter. By adjusting the axial-ratio (AR) of the elliptic cavity, the position of the introduced transmission zero could be moved to the upper side or the lower side of the passband. The micromachining process of deep reactive ion etching (DRIE) is used for the fabrication. The measured 3-dB bandwidth of the filter is 7.52%, from 380.2 to 409.9 GHz, and the measured insertion loss is 2.84 dB, including extra waveguide of about 4.5 mm at the input and output ports. In addition, the insertion loss of straight waveguide is also measured and analyzed. Then, an analysis method for the loss property is summarized. According to the measurement, the unit length loss of the waveguide is about 0.144 dB/mm at 400 GHz.

Design, fabrication and characterization of a photodefinable benzocyclobutene (BCB 4022-35 is a product of DowTM) single mode rib optical waveguide is presented in this work. At first, the refractive index of polymer film is measured by the method of prism coupling. We design the single mode rib waveguide based on the geometrical adjustment of rib width, total waveguide height using conventional R-soft BPM and effective index methods. Based on the design results, BCB waveguides were fabricated by using photolithographic process with wet etching, which is quite complicated and time consuming. In this work, the insertion and propagation losses of waveguide are measured by using the conventional cut back method. The insertion losses of waveguide are 3.95 dB and 4.08 dB for TE and TM modes respectively. The propagation losses of waveguide are 1.09dB/cm and 1.20dB/cm for TE and TM modes respectively. 

Most of the waveguide grating router's loss comes from fiber coupling and star coupler. Our three-dimensional (3-D) models quantifies both losses. In addition, we study how various waveguide parameters affect the value and nonuniformity of this loss. Our optimization yields a design where the total fiber-to-fiber insertion loss can be reduced to 0.535 dB.