Ceramic Waveguide Research Articles

Monolithic ceramic waveguide filter using a transition between GCPW feed and ceramic waveguide for 28 GHz

AbstractIn this letter, a mm‐wave monolithic ceramic waveguide filter using a transition between a grounded coplanar waveguide (GCPW) feed and a ceramic waveguide has been proposed. The published studies on monolithic ceramic waveguide filters with wideband properties for the mm‐wave are lacking. A desired external quality factor, satisfying wide bandwidth, is achieved using both inductive and capacitive couplings in the transition. The inductive coupling is realized with a waveguide's hole directly connected to the microstrip line probe of the GCPW. The capacitive coupling is employed with the slots of both GCPW and ceramic waveguide, which are placed facing each other. Adopting the presented transition, the inline monolithic ceramic waveguide filter for a fourth‐order Chebyshev response was designed. The fabricated filter provided the insertion and return losses of lower than 1.2 dB and higher than 10 dB, respectively, at frequencies from 26.43 to 29.76 GHz, with a fractional bandwidth of 11.85%.

High-Performance monolithic ceramic waveguide filter with isosceles Right-Angled triangular resonator for base station applications

This paper presents a high-performance integrated monolithic ceramic dielectric waveguide (DW) filter featuring isosceles right-angled triangular (IRAT) resonators. The fabrication process of the filter involves embedding a specific number of blind holes (BHs) or through holes/slots (THs/TSs) in a hexagonal ceramic dielectric block, fully metallizing the dielectric surface, and forming a monolithic ceramic DW filter. To achieve magnetic coupling, four THs and a BH are introduced in the oblique edges of two IRAT resonators; alternatively, a TS and BH are introduced in their right-angled edges. Electrical coupling is realized through a deep BH on the right-angle side of the resonators. Two non-adjacent resonators initiate weak cross-coupling by cascading a T-shaped rectangular TS, shallow BHs, and deep BH, creating two transmission zeros (TZs) outside the band. The filter was fabricated to ensure theoretical correctness and process reliability. The measured results show an insertion loss between 0.5 – 1 dB and a return loss greater than 18 dB at a bandwidth of 3.4 – 3.6 GHz. Two steep out-of-band TZs occur at 3.26 GHz and 3.72 GHz, aligning with simulation results. Therefore, the filter not only exhibits excellent performance but is also convenient for mass production and manufacturing, offering significant potential for future applications in 5G / 6G communication base stations.

Inkjet Printing of Yb:YAG Transparent Ceramic Planar Waveguide Laser Gain Medium

Herein, a YAG/10 at% Yb:YAG/YAG transparent ceramic planar waveguide (PWG) gain medium has been molded via inkjet printing and dry pressing molding. The composition and rheological property of ink are optimized along with the printing process to enhance the printing accuracy and quality. The PWG has dimensions of 13.5 × 8.0 × 1.8 mm3, while the thickness of the core Yb:YAG layer is ≈190 μm. The in‐line transmittance of the PWG reaches 81.7% at 1030 nm, and the average grain size is ≈2.3 μm. The diffusion characteristics of Yb ions across the interface between the cladding YAG layer and the core Yb:YAG layer are investigated by calculating the diffusion coefficient and the mean diffusion distance of 172Yb ions. The Yb:YAG PWG oscillator, which is pumped from a single end by a 940 nm laser diode, produces continuous wave laser at a wavelength of 1030 nm and exhibits the highest power (3.8 W) and highest absorbed–output slope efficiency (64.6%).

Microwave Frequency Offset Induced by Subsurface Damage in Abrasive-Machined Semiconductor Ceramic Waveguide

Ceramic waveguide components play a critical role in modern microwave semiconductor systems. For the first time, this work reports experimental results obtained when dielectric ceramics are abrasive-machined into waveguide components. This process will cause subsurface damage (SSD), resulting in a deviation in their working frequency which can degrade the performance of the system. For a substrate-integrated waveguide (SIW) resonator working at 10.1 GHz, SSD with a depth of 89 um can cause a maximum frequency offset of 20.2%. For a mm wave component working at 70 GHz, the corresponding frequency offset could increase to 169%. Three resonator SIW filters with SSD are studied, and the results demonstrate that the frequency offset induced by SSD can reduce the pass rate of the filters from 95.4% to 0%. A theoretical analysis is performed to reveal the mechanism and to offer a quantitative estimation of the limiting range of the offset caused by SSD. Feasible methods for reducing the offset caused by SSD, such as structure design, processing optimization, and material reinforcement, are discussed.

Design of a microwave filter based on a novel negative coupling structure with conical through-hole

This article introduces the design theory of ceramic waveguide filter and proposes a new type of negative coupling structure with a conical through-hole, which has fine-adjustment of negative coupling without significantly increasing the insertion loss of the filter. Based on this, the article proposes an eight-cavity ceramic waveguide filter design for 5G base stations. It also presents a detailed discussion on the influence of the cross-coupling slot lengths L2 and L4 on the transmission zeros positions during the filter optimization process and the relevant change rules. For the proposed optimized filter, the observed performance indicators include the center frequency of 3.5 GHz, working bandwidth of 200 MHz, an insertion loss of ≤ 2.0 dB, return loss of ≥ 19 dB, and out-of-band near-end suppression and out-of-band far-end suppression of ≥ 39 dB and ≥ 63 dB, respectively. The test performance results obtained for the sample, with structural parameters as per the simulation model, were in good agreement with the simulation results.

Additive Manufactured Waveguide for E-Band Using Ceramic Materials

Ceramic materials are chemical- and temperature-resistant and, therefore, enable novel application fields ranging from automotive to aerospace. With this in mind, this contribution focuses on developing an additive manufacturing approach for 3D-printed waveguides made of ceramic materials. In particular, a special design approach for ceramic waveguides, which introduces non-radiating slots into the waveguides sidewalls, and a customized metallization process, are presented. The developed process allows for using conventional stereolithographic desktop-grade 3D-printers. The proposed approach has, therefore, benefits such as low-cost fabrication, moderate handling effort and independence of the concrete waveguide geometry. The performance of a manufactured ceramic WR12 waveguide is compared to a commercial waveguide and a conventionally printed counterpart. For that reason, relevant properties, such as surface roughness and waveguide geometry, are characterized. Parsing the electrical measurements, the ceramic waveguide specimen features an attenuation coefficient of 30–60 dB/m within the E-Band. The measured attenuation coefficient is 200% and 300% higher compared to the epoxy resin and the commercial waveguide and is attributed to the increased surface roughness of the ceramic substrate.

Millimeter-Wave Dielectric Slab-Based Chip-to-Chip Interconnect Network Allowing for Relaxed Assembly Tolerances

An on-chip, low-loss, and wideband transition to dielectric slab waveguide is proposed in this article, for millimeter-wave interchip communication network applications. The transition design features a three-terminal circuit with one on-chip planar microstrip line and two off-chip dielectric slab-waveguide ports. It presents an add-drop attribute, which can be employed to realize the traditional bus and backbone network topologies. Prototypes presented operate on a thin-film layer imitating the back-end-of-line layers of a chip. Measurements are performed for an end-to-end connection and a hexagonal ring interconnect network at 170 and 100 GHz, respectively. In addition, the proposed transition is shown to enable an equal signal power distribution scheme in a linear array of receivers. To provide much needed relaxation against mechanical tolerances and thermal expansion effects in multiport circuits based on the ceramic dielectric waveguide, a novel low-loss and mechanically flexible connection between two dielectric slab waveguides is presented. The design of this connection, operating from 80 to 100 GHz, is verified by measurements. Technical merits, packaging attributes, and limitations of the proposed single hierarchy interchip interconnect network are discussed.

소형 세라믹 모노블록 도파관 듀플렉서

소형 세라믹 모노블록 도파관 듀플렉서

A Low-Loss Fan-Out Wafer-Level Package With a Novel Redistribution Layer Pattern and Its Measurement Methodology for Millimeter-Wave Application

A low-loss fan-out wafer-level package (FOWLP) has been proposed for millimeter-wave application. To ensure the radio frequency (RF) signal transition in a ground–signal–ground (GSG) configuration, the signal structure in the redistribution layer (RDL) is tightly surrounded by its ground. Over a wideband, the proposed RDL structure results in a low loss and a good match at the RF port. Moreover, an efficient measurement methodology has been proposed for the millimeter-wave package. By adopting a 50- $\Omega $ ceramic coplanar waveguide (CPW), performance of the millimeter-wave package is assessed by probes. This measurement method features quite a low measurement error because insertion loss of the added ceramic CPW is very small. By the proposed cascade de-embedding method, the parasitic effects resulting from the interconnections can be removed and the package performance can be achieved. The measured insertion loss for the proposed package is around 1 dB and the measured 10-dB return loss bandwidth is from 70 to 85 GHz.

An Efficient Analysis Method for LTCC Ridge Waveguide Bandpass Filters via Database Searching

Low temperature cofired ceramic (LTCC) ridge waveguide filters are attractive candidates in implementing microwave filters in modern communication systems because of their competitive features, such as low loss, low cost, compact size, lightweight, high-power handling capability, wide spurious-free out-of-band response, and easy integration. However, optimization of LTCC ridge waveguide filters suffers from low speed or imperfect accuracy when the traditional full-wave simulation or the mode-matching method is utilized for analysis. This article makes research on an alternative analysis method based on the network theory for LTCC inline ridge waveguide filters. The method has high speed since it evaluates filter properties by simply making the cumulative product of transfer matrices of all constitutive laminated ridge waveguide (LRWG) sections and laminated coupling (LCP) sections according to their arranging sequence, and transfer matrices of all these sections are calculated from their characteristic parameters (transmission line or equivalent circuit parameters for LRWG or LCP sections) analytically. Another key feature of the method is that all characteristic parameters of LRWG and LCP sections are obtained by searching precreated database. In order to guarantee the analysis accuracy, two special strategies have been proposed and utilized. First, accurate extraction methods of characteristic parameters have been introduced and applied to the creation of a database for LRWG and LCP sections. Second, a piecewise interpolation scheme has been designed and adopted in the database searching process for both kinds of sections. The efficiency of the promoted analysis method has been verified by two analysis examples of LTCC LRWG filters. One is a three-order narrow-band filter and the other is a nine-order wide-band filter. The curves of scattering parameters calculated using the promoted method agree well with the simulated curves and the time consumed by the method is negligible when compared with the simulation time. The effectiveness of the proposed analysis method in filter design is also briefly introduced in this article.

MXene Ti3C2Tx saturable absorber for passively Q-switched mid-infrared laser operation of femtosecond-laser–inscribed Er:Y2O3 ceramic channel waveguide

Abstract We report on an Er:Y2O3 ceramic channel waveguide laser operating at continuous-wave and passively Q-switched regimes, for the first time to the best of our knowledge. The Er:Y2O3 ceramic channel waveguide has been fabricated by a femtosecond laser direct-writing technique. The maximum output power reached 123.5 mW in continuous-wave mode with a slope efficiency of about 21%, and the lasing behavior has been found simultaneously at 2710.28, 2716.76, and 2723.18 nm. We have further fabricated an MXene Ti3C2Tx saturable absorber mirror to operate the Er:Y2O3 waveguide in passively Q-switched regime. At the same time, property of the MXene Ti3C2Tx saturable absorber has been characterized, and nonlinear saturable absorption of the saturable absorber has also been measured. The average output power is about 67.6 mW, and the shortest pulse width is about 58.1 ns. This work indicates that femtosecond laser direct writing is a reliable technique for processing mid-infrared ceramic waveguides, and MXene Ti3C2Tx is promising for operating pulsed mid-infrared lasers.

Spurious Suppression of Ceramic loaded filter with different Ceramic Permittivity

This work presents the 3rd order ceramic waveguide filters with improved stopband performance. The idea utilizes ceramic loaded resonators with different permittivity’s and TEM loading. The overall response spreads out the higher order resonances by integrating the effects of different 𝜀𝑟 and TEM without affecting the overall performance of a filter. The simulated results of a 3rd order ceramic loaded waveguide filter is presented, which is in good agreement with the idea.

Pump coupling optimization of a native inhomogeneous planar waveguide laser

Abstract Planar waveguide laser is a promising candidate for high power solid state lasers. Normally the native inhomogeneous refractive index exists during fabrication process, this will apparently affect power scaling and beam quality. Few quantitative works have been reported to the optimization of this behavior and in practice, try and error routine is needed to set pump conditions. In this work, we manufactured a miniature composite Yb:YAG ceramic waveguide laser via non-aqueous tape casting method, refractivity index gradience is natively generated via border diffusion between the Yb:YAG and YAG layers. We found a simple and effective criterion to treat pump optimization by combining wave optics model and laser rate equations. Guided by this criterion, we obtained an experimental slope-efficiency about 66% with optimized pumping beam parameters. This method could be forward applied in similar designs and much higher power planar waveguide lasers.

Study of a Dielectric Ceramic Waveguide Filter with Asymmetric Transmission Zeros by Using Cascaded Trisection

Study of a Dielectric Ceramic Waveguide Filter with Asymmetric Transmission Zeros by Using Cascaded Trisection

Characterization of Silica Extracted from Rice Husk Ash Wastes Doped by Tin Dioxide for Wave Guide Material

A series of experiments is made to produce silica, mixing with tin dioxide (SnO2), and characterizing for application of waveguide device. Silica xerogels (SX) are prepared from raw materials derived from rice husks ash (RHA), which abundant in South East Sulawesi. The synthesis conditions have been optimized to obtain the ash of rice husks with the maximum silica content. SnO2 are prepared from a commercial powder. The ceramic waveguide materials are produced by mixing SX and SnO2 with various composition. The mixtures are molded to form the rectangular shape of 20 mm, 40 mm, and 5 mm in size. The samples will be sintered at different level of temperatures (from 300°C to 1200°C) by using microwave heating system as well as electric furnace. The microstructural of sintered samples were characterized on the basis of the experimental data obtained using densification measurement method (Archimedes method), crystallization (X-ray diffraction, XRD), microstructure (Scanning electron microscope, SEM). Optical and related properties such as the functional groups, structure, and absoption were characterized by using FTIR, Infrared and Raman Spectroscopy and absorption (UVVis). The permittivity and permeability will be calculated from S-parameters determined by using Vector Network Analyzer (VNA). Characterization results are presented in this paper and the others are will be published in another separated papers. Furthermore, the relationship between properties with SnO2 content and sintering temperature is also studied.

Gain and noise figure analysis of Er3+-doped YAG transparent ceramic microchip amplifier

The rate equations and the power evolution equations based on excited state absorption (ESA) and cooperative upconversion (CUC) of high concentration erbium-doped yttrium aluminum garnet (YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure (NF). The numerical analysis predicts that with a pump power of 100mW, an active ion concentration of 1.0×1026 ion/m3 and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier.

High power YAG/Nd:YAG/YAG ceramic planar waveguide laser

A high power YAG/Nd:YAG/YAG ceramic planar waveguide laser was demonstrated. For continuous wave regime, a maximum output power of 10.4 W at a center wavelength of 1064.6 nm was obtained under an absorbed pump power of 17.4 W, corresponding to an optical-to-optical conversion efficiency of 59.8%. For acousto-optically Q-switched operation, we obtained 2.5 W of output power at a pulse repetition frequency of 10 kHz. The pulse duration was 6.5 ns with peak power and pulse energy of 38.5 kW and 0.25 mJ, respectively.

Densification behavior, doping profile and planar waveguide laser performance of the tape casting YAG/Nd:YAG/YAG ceramics

The sintering behavior and doping concentration profile of the planar waveguide YAG/Nd:YAG/YAG ceramics by the tape casting and solid-state reaction method were investigated on the basis of densification trajectory, microstructure evolution, and Nd3+ ions diffusion. The porosity of the green body by tape casting and cold isostatic pressing is about 38.6%. And the green bodies were consolidated from 1100 °C to 1800 °C for 0.5–20 h to study the densification and the doping diffusion behaviors. At the temperature higher than 1500 °C, pure YAG phase is formed, followed by the densification and grain growth process. With the increase of temperature, two sintering stages occur, corresponding to remarkable densification and significant grain growth, respectively. The mechanism controlling densification at 1550 °C is grain boundary diffusion. The diffusion of Nd3+ ions is more sensitive to temperature than the sintering time, and the minimum temperature required for the obvious diffusion of Nd3+ ions is higher than 1700 °C. Finally, planar waveguide YAG/1.5 at.%Nd:YAG/YAG transparent ceramics with in-line transmittance of 84.8% at 1064 nm were obtained by vacuum-sintering at 1780 °C for 30 h. The fluorescence lifetime of 4F3/2 state of Nd3+ in the specimen is about 259 μs. The prepared ceramic waveguide was tested in a laser amplifier and the laser pulse was amplificated from 87 mJ to 238 mJ, with the pump energy of 680 mJ.

Ceramic planar waveguide laser of non-aqueous tape casting fabricated YAG/Yb:YAG/YAG.

Ceramic YAG/Yb:YAG/YAG planar waveguide lasers were realized on continuous-wave and mode-locked operations. The straight waveguide, fabricated by non-aqueous tape casting and solid state reactive sintering, enabled highly efficient diode-pumped waveguide continuous-wave laser with the slope efficiency of 66% and average output power of more than 3 W. The influence of the waveguide structure on the wavelength tunability was also experimentally investiccgated with a dispersive prism. Passively mode-locked operation of the ceramic waveguide laser was achieved by using a semiconductor saturable absorber mirror (SESAM), output 2.95 ps pulses with maximum power of 385 mW at the central wavelength of 1030 nm.

Longitudinally diode-pumped planar waveguide YAG/Yb:LuAG/YAG ceramic laser at 10307 nm

Composite YAG/15 at. % Yb:LuAG/YAG transparent ceramic planar waveguide was fabricated by a tape casting method and vacuum sintering technology. Under a 970 nm diode laser pumping, the absorbed efficiency of 85.4% was achieved, and efficient CW laser operation at 1030.7 nm was accomplished with a good beam quality with Gaussian spatial profile. A maximum output power of 288 mW was obtained under a pump power of 4.69 W, corresponding to a slope efficiency of 9% and an O-O conversion efficiency of 5%.