
Pentti KariojaVTT Technical Research Centre of Finland Ltd
Pentti Karioja
D.Sc. (Tech)
About
128
Publications
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Introduction
Publications
Publications (128)
Development of mid-infrared photonics is gaining attention, driven by a multitude of sensing applications requiring increasingly compact and cost-effective photonics systems. To this end, low-loss operation of µm-scale silicon-on-insulator photonic integration elements is demonstrated for the 2.6–2.7 µm wavelength region. The platform utilizes the...
VTT Technical Research Centre of Finland Ltd. has developed and utilized Low Temperature Co-fired Ceramic (LTCC) technology for about 25 years. This paper presents our activities related to photonics and millimetre-waves, including also a relevant literature survey. First a short summary of the technology is given. Especially, the unique features o...
Surface-enhanced Raman spectroscopy (SERS) is considered a highly promising technology for different analytical purposes. The applications of SERS are still quite limited due its relatively poor quantitative repeatability and the fact that SERS is very sensitive to oxidation, which is a challenge especially with silver based SERS substrates. Here,...
Flexible photonic integrated circuit technology is an emerging field expanding the usage possibilities of photonics, particularly in sensor applications, by enabling the realization of conformable devices and introduction of new alternative production methods. Here, we demonstrate that disposable polymeric photonic integrated circuit devices can be...
To enable wide spread dissemination of sensors in cost-critical applications and resource poor settings, methods to implement sensor chips using low-cost materials and mass-manufacturing methods are developed. In this paper we demonstrate that disposable polymeric integrated Young interferometer (YI) sensor chips, implemented on roll-to-roll mass-m...
We present a polymer-based optofluidic surface enhanced Raman scattering chip for biomolecule detection, serving as a disposable sensor choice with cost-effective production. The SERS substrate is fabricated by using industrial roll-to-roll UV-nanoimprinting equipment and integrated with adhesive-based polymeric microfluidics. The functioning of th...
Optical interferometry is a well-known, highly regarded and powerful measurement technique that is used in many forms to perform a very wide range of measurements. Applications of interferometry range from source characterisation to material characterisation; from OCT to photonic sensing; and from space weather monitoring to gravitational wave dete...
In order to fulfill the specifications of photonic sys-tems, various optoelectronic chips, MEMS, MOEMS and RF-MEMS devices, micro-optical elements and integrat-ed circuits needs to be integrated into functional compo-nents, modules and systems. The sub-systems of the pho-tonic system must be fabricated by the use of cost-efficient, reproducible, we...
We have demonstrated a proof-of-concept for an athermal silicon slot waveguide using Ormocomp as a top cladding. Preliminarily theoretical and experimental results show that the slot waveguide geometry can completely cancel out its thermo-optical coefficient, by tailoring the optical mode overlap with silicon, silicon dioxide, and Ormocomp.
Miniaturization and cost reduction of spectrometer and sensor technologies has great potential to open up new
applications areas and business opportunities for analytical technology in hand held, mobile and on-line applications.
Advances in microfabrication have resulted in high-performance MEMS and MOEMS devices for spectrometer
applications. Many...
Polymers have become an important material group in fabricating discrete photonic components and integrated optical devices. This is due to their good properties: high optical transmittance, versatile processability at relative low temperatures and potential for low-cost production. Recently, nanoimprinting or nanoimprint lithography (NIL) has obta...
This paper describes experimental measurement results for photonic crystal sensor devices which have been functionalized for gas sensing applications. The sensor consists of a two dimensional photonic crystal etched into a slab waveguide having a refractive index of 1.7-1.9. Test devices were fabricated from SiON material on silicon / silicon dioxi...
A fully polymer slot Young interferometer operating at 633 nm wavelength was fabricated by using nanoimprint molding method. The phase response of the interference pattern was measured with several concentrations of glucose-water solutions, utilizing both TE and TM polarization states. The sensor was experimentally found to detect a bulk refractive...
A refractive index sensor based on slot waveguide Young interferometer was developed in this work. The interferometer was fabricated on a polymer platform and operates at a visible wavelength of 633 nm. The phase shift of the interference pattern was measured with various concentrations of glucose-water solutions, utilizing both TE and TM polarizat...
To improve thermal performance of high-power chip-on-board multichip LED module, a copper-core metal core printed circuit board (MCPCB) substrate with copper filled microvias is introduced. As a reference, the performance is compared with alumina modulewith the same layout by means of thermal simulations and measurements. Up to 55% reduction in the...
A nanoimprint mold for optical waveguide applications was fabricated by combining photolithography and focused ion beam (FIB) milling. The feasibility of the proposed method was demonstrated by imprinting 15-mm-long Y-branch waveguides, which had nanoscale slots embedded in one arm. Structural analysis of the FIB milled region showed surface roughn...
A novel portable methane sensor demonstrator based on Low Temperature Co-fired Ceramic (LTCC) differential Photo Acoustic (PA) cell, silicon cantilever and spatial interferometer was demonstrated. Silicon Micro-Electro-Mechanical-System (MEMS) cantilever-based PA technology allows sensing of extremely low gas concentrations with wide dynamic measur...
Polymeric slot waveguide structure, which pushes the mode field toward the surrounding media, was designed and characterized. The slot waveguide was fabricated by using nanoimprint lithography, and the operation of the slot was demonstrated at 633 nm wavelength with an integrated Young interferometer. The experimental result shows that the nanolith...
An evanescent field sensor utilizing layered polymeric-inorganic composite waveguide configuration was developed in this work. The composite waveguide structure consists of a UV-imprint patterned polymer inverted rib waveguide with a Ta2O5 thin film sputter-deposited on top of the low refractive index polymer layers. The results suggest that the po...
In this work, we investigate the usability of layered polymer - inorganic composite waveguides for label-free sensing of surface bound bioreactions in an aqueous environment. The waveguide structure consists of a nanoimprint fabricated polymeric inverted rib waveguide with a sputtered Ta<sub>2</sub>O<sub>5</sub> thin film on top. The interaction of...
In this work, we investigate the usability of layered polymer -
inorganic composite waveguides for label-free sensing of surface bound
bioreactions in an aqueous environment. The waveguide structure consists
of a nanoimprint fabricated polymeric inverted rib waveguide with a
sputtered Ta2O5 thin film on top. The interaction of the optical field
wit...
Low-loss polymeric optical waveguides were fabricated by
UV-nanoimprinting. With this technique the waveguides are directly
patterned by imprinting of the UV-curable optical polymer materials,
i.e. no etching processes are needed. By properly manufactured
imprinting molds, very smooth waveguide surfaces are achieved and the
optical loss is dominate...
This paper presents research activities carried out at VTT Technical
Research Centre of Finland in the field of hybrid integration of optics,
electronics and mechanics. Main focus area in our research is the
manufacturing of electronic modules and product structures with printed
electronics, film-over-molding and polymer sheet lamination technologi...
Polymers are applicable materials for photonic device fabrication due to their good optical properties and versatile processability at low temperatures, and therefore, provide possibility for low-cost fabrication. For waveguide device fabrication, the most critical requirement is the selection of the patterning method for the ridge that is bounding...
We discuss the applicability of using polymers for producing slot waveguide modes in single and triple-slot waveguide structures. We use finite element method to computationally study the field confinement and enhancement in the slot region with and without high refractive index coating on the top of the low index polymeric waveguide. The sensitivi...
Polymers are important materials in fabrication of photonics devices due to their good optical properties, such as, high transmittivity, versatile processability also at low temperatures allowing potential for low-cost fabrication. A critical requirement in the fabrication of integrated optical devices has been selecting a most suitable method for...
We discuss the manipulation of optical field distribution in a low-refractive index polymeric waveguide by depositing a thin high refractive index Ta2O5 film on top of the waveguide. According to microstructure studies, the sputtered Ta2O5 thin films deposited on the polymer layer were very smooth with root mean square surface roughness value of 0....
Microelectronic Engineering Vol.88 Nr.2, 175-178 In this paper we introduce a fabrication process for polymer rib waveguides that uses UV-imprint lithography. In the structure of an inverted-rib waveguide, the lower cladding of the waveguide is patterned by UV-imprinting and the waveguiding layer is subsequently spin-coated. That makes the thicknes...
The fabrication of polymer based waveguide devices by different methods is investigated in this work including lithographic, imprinting and focused-ion-beam processing. Also, the combination of luminescent substance with waveguide is evaluated to produce integrated optical micro system including both the light source and sensor structure on a singl...
Proceedings of SPIE - The International Society for Optical Engineering, Article number 77260H Vol.7726 Optical Sensing and Detection. Brussels, Belgium, 12 - 15 April 2010
Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, th...
Optical ridge type waveguides based on UV-curable polymer were fabricated by imprinting method. Positive tone resist patterned on a silicon wafer was used as a mould. The characterization of waveguides was carried out by coupling TE-polarized light from a tapered fiber into a waveguide with 30 mm length and mapping the intensity distribution with a...
A hermetic fiber pigtailed laser module utilizing passive device alignment on a low-temperature cofired ceramics (LTCC) substrate is demonstrated. The 3-D shape of the laminated and cofired ceramic substrate provides the necessary alignment structures, including grooves and cavities, for the laser-to-fiber coupling. When the laser diode chip and co...
This paper describes interchannel crosstalk in a parallel optical receiver at a data rate of 10 Gb/s and higher. Individual paths of interchannel crosstalk are categorized, and each path is investigated in detail with equivalent model measurements and simulations. At a frequency of 10 GHz, three individual package substrate crosstalk paths and supp...
Optical properties of ferroelectric BaTiO3 (BTO) and paraelectric SrTiO3 (STO) multilayer structures were investigated as a possible material choice for thin-film electro-optic devices. It has been demonstrated that dielectric properties can be enhanced by optimizing the stacking periodicity of BTO-STO superlattices, and in this work, it was studie...
An important challenge that remains to date in board level optical interconnects is the coupling between the optical waveguides on printed wiring boards and the packaged optoelectronics chips, which are preferably surface mountable on the boards. One possible solution is the use of Ball Grid Array (BGA) packages. This approach offers a reliable att...
The performance of short distance optical interconnections in general relies very strongly on coupling structures, since they will determine the overall efficiency of the system to a large extent. Different configurations can be considered and a variety of manufacturing technologies can be used. We present two different discrete and two different i...
A displacement measurement technology of diffractive interferometry has been developed in the objective of miniaturization. The interference principle has been implemented in the form of a miniature read head prototype according to a novel device configuration. The read head developed at TSI can be miniaturized utilizing 3D hybrid integration and p...
The optical analyzers used in on-line and off-line process measurements set a large variety of special demands for optical detectors, i.e. customized detectors are needed. Both the detector (array) and its read-out circuit are affected. The typical volume for process analyzers is so low that fully customized ASICs easily become too expensive for si...
A microscope add-on device to a 1.3 Mpix camera phone was selected as a demonstrator system for testing inmould integration of electronic substrates and plastic optics. Optical design of the device was quite challenging due to the fact that illumination system needed to be integrated with a double aspheric singlet lens structure as a single optical...
A red VCSEL illuminator module demonstrator was manufactured by injection moulding integration. A red VCSEL chip was first attached to a simple FR4 substrate, which contains bonding pads and conducting wires for the VCSEL chip attachment and electrical driving. The substrate was then placed as an insert in an injection mould. The VCSEL chip shieldi...
We have studied methods to design and fabricate coupling structures for short distance optical interconnects on printed wiring boards (PWBs). In order to demonstrate the developed technologies, a parallel optical interconnect was integrated on a standard FR4-based PWB by using surface-mounted component packages and board-embedded optical waveguides...
In-mould integration of bare and glob-top shielded LED chips was demonstrated in an injection moulding process. The LED chips were first attached on conventional FR4 substrates and the substrates were used as inserts in the injection moulding process. Test series of 39 modules containing four green LED chips and 80 modules containing one blue chip...
A vacuum package was designed and manufactured for the testing of a MEMS-based thermal imaging detector array. Optimum operation of the pixel array requires low pressure and stabilized temperature. The pixel array devices are under development; therefore, the package needs to be reusable as a test fixture for chip revisions. Two optical windows are...
A novel method to laminate and co-fire LTCC tapes directly on a heat sink was studied. Several tape systems, including combination of mixed permittivities, and heat sink material options have been demonstrated. The critical issue in the selection of materials was the compatibility of CTE values between different materials due to wide temperature ra...
A concept that utilizes structured planar substrates based on low-temperature cofired ceramics (LTCC) as a precision platform for a miniature passive alignment multimode laser module is demonstrated. The three-dimensional shape of the laminated and fired ceramic substrate provides the necessary alignment structures including holes, grooves, and cav...
In photonic module integration, optoelectronic chips, microoptical elements and integrated circuits are integrated into functional components, subassemblies, modules and systems. The building bl°Cks of the photonic system must be fabricated by the use of costefficient, reproducible, wellestablished, highvolume manufacturing technologies. The reliab...
In this paper we give an overview of the fabrication and assembly induced performance degradation of an intra-multi-chip-module free-space optical interconnect, integrating micro-lenses and a deflection prism above a dense opto-electronic chip. The proposed component is used to demonstrate the capabilities of an accurate micro-optical rapid prototy...
Technologies to design and fabricate high-bit-rate chip-to-chip optical interconnects on printed wiring boards (PWB) are studied. The aim is to interconnect surface-mounted component packages or modules using board-embedded optical waveguides. In order to demonstrate the developed technologies, a parallel optical interconnect was integrated on a st...
A hermetic fibre pigtailed laser module utilizing passive device alignment on a low temperature co-fired ceramics (LTCC) substrate is demonstrated. The 3-dimensional shape of the laminated and fired ceramic substrate provides the necessary alignment structures including holes, grooves and cavities for the laser to fibre coupling. The achieved passi...
Finland is well known as a high technology country and when it comes to ceramic technology the central or Northern part of the country has long traditions in both research and volume production. Under the global pressure the players in the Oulu and Kemi region have recently joined forces in analysing what technologies are needed and what can be off...
We have studied technologies to design and fabricate high-bit-rate chip-to-chip optical interconnects on printed circuit boards (PCBs) using board-embedded polymer waveguides and surface-mounted component packages or modules. In order to demonstrate the developed technologies, a 4times10 Gb/s optical interconnect was completely integrated on a stan...
A network for prototyping imaging lenses using injection moulding was established in Finland. The network consists of several academic and industrial partners capable of designing, processing and characterising imaging lenses produced by injection moulding technology. In order to validate the operation of the network a demonstrator lens was produce...
In the module integration process, lower level packaging elements such as devices, sub-mounts and components are combined as a functional block. Embedded sub-system consists of modules whose operations are controlled by a specific algorithm. Typically, the control algorithm is realized in a form of system software in a processor unit, which control...
Purpose
The aim of the research was to evaluate the concept that utilizes structured planar substrates based on low temperature co‐fired ceramics (LTCC) as a precision platform for the passive alignment of a multimode fiber and wide‐stripe diode laser.
Design/methodology/approach
Presents the manufacturing process for realisation of 3D precision s...
We realized a prototype series of the 1550-nm band wavelength-tunable laser module. The edge-emitting Fabry-Perot diode laser operates in the short external cavity configuration and is tuned by a silicon surface micromachined Fabry-Peacuterot interferometer device. Low-temperature cofired ceramic (LTCC) substrate technology was used in the module p...
Low temperature co-fired ceramic (LTCC) technology was developed for high-power applications. LTCC tapes were directly laminated and fired on heat sink, which dissipates effectively the heat and increases the mechanical strength of the LTCC module. The thermal and thermo-mechanical simulations were used to assist in material and geometry selections...
A novel design of an underwater acoustical pressure transducer based on a Fiber Bragg Grating is presented. In this transducer the sensing grating is writen in a rare-earth doped fiber and operates as an optically pumped Distributed Feedback (DFB) laser. Presented sensor has higher resolution, compared to a sensor using a passive Fiber Bragg Gratin...
Integration of high-speed parallel optical interconnects into printed wiring boards (PWB) is studied. The aim is a hybrid optical–electrical board including both electrical wiring and embedded polymer waveguides. Robust optical coupling between the waveguide and the emitter/detector should be achieved by the use of automated pick-and-place assembly...
A novel design of an interferometric hydrophone transducer is presented. It consists of a coil of fiber embedded in a layer of epoxy. Finite Element modeling of such transducer is difficult due to anisotropic mechanical properties of its structure. An approach based on laminate modeling techniques was adopted. Static and modal Finite Element analys...
In the last decade, the processing of the waveguide structures on various substrates under mild conditions has been an appealing aim. The lithographic patterning of organic-inorganic hybrid materials processed by means of sol-gel technology allows the production of waveguides and other optical components. We describe the synthesis of a new, photo-p...
The current modulation characteristics of a short external cavity tunable laser are presented. The 1540 nm Fabry-Perot diode laser is wavelength-tuned by the electrostatically controlled silicon micromachined Fabry-Perot interferometer device. The measured -3 dB cutoff frequency of 600 MHz is the widest reported direct modulation bandwidth of the e...
The modeling, realization and characterization of photonic module based on the use of Low Temperature Co-fired Ceramics (LTCC) technology is reported. The 3D modeling of the system provides possibility to optimize structures, materials and components in order to achieve optimal performance for the final product and still maintain reasonably low fab...
Integration of high-speed parallel optical interconnects into printed wiring boards (PWB) is studied. The aim is a hybrid optical-electrical board including both electrical wiring and embedded polymer waveguides. Robust optical coupling between the waveguide and the emitter/detector should be achieved by the use of automated pick-and-place assembly...
We realized a wavelength-tunable laser using a 1540-nm Fabry-Pe´rot diode laser and a silicon surface micromachined Fabry-Pe´rot interferometer device in the short external cavity configuration. This hybrid-integrated system enables the use of standard laser chips and potentially has a low cost. We obtained single-mode tuning of 13 nm, a sidemode s...
In the case of imaging optics for imaging cellular phones, special attention has to be paid on the cost of the lens system. The number of lens elements has to be minimized, but the image quality has to be maximized. It is important that optimum quality/cost - ratio is found. The image sensor characteristics and human visual system preferences have...
In this paper, an imaging system simulation tool is presented. With the tool, it is possible to simulate the performance (quality) of an imaging system. Furthermore, the system allows optimization of the lens system for a given image sensor. Experiments have shown that the tool is useful in actual lens design.
The use of low-temperature co-fired ceramic (LTCC) substrate as a wiring board for a silicon surface micromachined Fabry-Perot interferometer (FPI) device is presented. FPI is an electrically controlled optical bandpass filter that is widely used in spectroscopy. In this paper, the FPI device is applied to demonstrate a wavelength tunable diode las...
The prototyping process of miniaturized plastic imaging lens is described. The sequence is divided into five phases: specification, optics design, optomechanical design, manufacturing and characterization. During specification, the optical and mechanical requirements of the lens are defined. In the optical design phase, the lens is optimized, and a...