Optical Waveguide Layer Research Articles

Building integrated concentrating photovoltaic window coupling luminescent solar concentrator and thermotropic material

Building integrated concentrating photovoltaic window (BICPVW) has been proven to be used in sustainable building transparent envelopes. Unfortunately, the balance between optical and electrical properties is difficult. This paper proposes a building integrated concentrating photovoltaic window coupling luminescent solar concentrator and thermotropic material (LT-BICPVW). The luminescent solar concentrator and thermotropic layer were fabricated by bulk polymerization and glass sandwich structure, respectively. Optical models are built based on the optical properties of optical waveguide and thermotropic layer, and optical simulations are performed with Monte Carlo ray tracing technology. Window prototypes are characterized under controlled indoor experimental conditions. The experiment found that as the temperature of the thermotropic film increased from 30 °C to 42 °C, the solar transmittance of LT-BICPVW decreased by 43.3%, and the maximum output power increased by 25%. Compared with, building integrated concentrating photovoltaic window coupled with thermotropic material (T-BICPVW), the power conversion efficiency was improved by 59% at the termination temperature. The LT-BICPVW system can effectively reduce solar heat gain and avoid glare hazards, while using renewable energy to significantly increase power output. A series of predictions are made using validated optical model and tracking technique to better guide the design of PV windows in actual buildings.

Toward GaSb-Based Monolithically Integrated Widely-Tunable Lasers for Extended Short- and Mid-Wave Infrared Wavelengths

A fully-functional photonic integrated circuit (PIC) platform with supporting active and passive components in the extended short- and mid-wave infrared spectral regime is of significant research interest for next-generation optical systems. Here we design offset quantum well-based photonic integrated circuits which primarily consist of four section-based widely tunable single-mode lasers emitting at 2560 nm. The platform requires the selective removal of InGaAsSb multi-quantum wells located above a GaSb-based optical waveguide layer and then subsequent single blanket GaSb regrowth. Encouraging preliminary experimental results on regrowth are also reported to confirm the feasibility of the proposed PICs. The simulation result for the tunable laser design shows that a tuning range as wide as ~120 nm is possible. The quasi-theoretical work performed here is an initial step towards demonstrating complex non-telecommunication PICs which could offer a comprehensive range of photonic functionalities.

Tunable fano resonance-enhanced surface plasmon biosensor based on MXene/MoS2 heterostructure

Two-dimensional materials have unique physical properties such as high electrical conductivity, excellent light absorption, and hydrophilicity, thus have been widely used as responsive materials for surface plasmon effect sensors in recent years. Here, we propose a Kretschmann configuration-based MXenes/MoS2 heterostructure film material as an improved sensing layer for surface plasmon resonance (SPR) sensors and introduce an optical waveguide layer into the nanostructure to achieve a remarkable Fano resonance (FR). By separately adjusting the thickness and refractive index of the coupling dielectric and optical waveguide layers, the effective coupling between the surface plasmon polarization and the planar optical waveguide mode is achieved, which significantly improves the sensor's response performance to biomolecules and achieves high sensitivity (S, 86.13°/RIU) and better figure of merit (FOM, 281.74 RIU−1) in the visible red range (around 632.8 nm). Benefiting from the light absorption gain of the heterostructure and the FR effect, the FOM of the MXene/MoS2 Fano resonance sensor (FRS) is improved by 7.1 times compared to the traditional SPR sensor based on noble metal Au (50 nm thickness) thin film.

Manufacturing of Er[formula omitted]-doped planar waveguides on silica-on-silicon using femtosecond laser-induced plasma

We report fabrication and characterisation of the erbium-doped planar waveguide on a silica-on-silicon (SOS) wafer-offering low loss and strong light confinement suitable for engineering optical waveguide amplifier for the C-band (1530–1565 nm) of the optical fibre communication. Here we describe an ultrafast laser plasma doping (ULPD) technique that is carried out using the plasma induced by a femtosecond laser (wavelength 800 nm) with a repetition rate of 10 kHz and a pulse duration of 45 fs. The ULPD method presented here had been applied successfully for rare earth materials doping on SOS substrates previously using a fs-laser with a pulse duration of ∼100 fs and at a repetition rate of 1 kHz. The fabricated planar optical waveguide layer onto the SOS substrate has been analysed for thickness, refractive index, optical propagation loss, photoluminescence intensity, and photoluminescence lifetime. We report a low propagation loss of <0.4 dB/cm in the C-Band, a long lifetime of 13.21 ms at 1532 nm, and the largest lifetime-density product 6.344 ×10 19 s cm −3. The low loss planar slab waveguide and a high lifetime-density product promise the further possibility of fabricating strip-loaded waveguides on the SOS platform. The proposed active waveguide fabrication methodology is potentially useful for manufacturing planar integrated optical waveguide amplifiers and lasers compatible with silicon-based photonic integrated circuits.

A highly sensitive and selective optical waveguide sensor based on a porphyrin-coated ZnO film

A highly sensitive and selective optical sensor device based on a porphyrin-coated ZnO thin film/K+ ion-exchanged glass composite optical waveguide (COWG) layer was developed. The surface of the ZnO film was coated with a thin film of 5,10,15,20-tetrakis-(4-methoxyphenyl) porphyrin by the spin-coating or immersion method. The optical properties of the films were probed by UV–vis and Fourier-transform infrared spectroscopies. The gas sensing performance was also examined in detail. The high sensitivity, room temperature operation, good selectivity, and reproducibility of the sensor render it a promising candidate for industrial use and in environmental monitoring.

Multi-layer stacking scheme of sol-gel based SiO&lt;sub&gt;2&lt;/sub&gt; towards thicker (&gt;0.8 µm) cladding layers for optical waveguides

Multi-layer stacking scheme of sol-gel based SiO&lt;sub&gt;2&lt;/sub&gt; towards thicker (&gt;0.8 µm) cladding layers for optical waveguides

Opto-Electronic Chip-on-Film Packaging Technology Using Low-CTE Fluorinated Polyimide Optical Waveguide Films

We have developed a new type of single-mode optical waveguide film with a low coefficient of thermal expansion (CTE). The low-CTE film was fabricated by sandwiching a fluorinated polyimide optical waveguide layer between low-CTE polyimide layers. Its CTE is less than one-tenth that of conventional polyimide optical waveguide films. We fabricated opto-electronic (OE) films with coplanar waveguide lines on the film surface using this low-CTE film. We confirmed that the film has good optical, electrical, and mechanical characteristics. This low-CTE OE film can be used to integrate optical and electrical devices on a film.

Flexible Thin Film Display Based on Optical Waveguide for Signage

Flexible thin film displays based on optical waveguide have been demonstrated. Flexible thin film displays consist of light source, optical waveguide, and scatters. Here, scatters have a role to change the direction of light source from parallel to perpendicular to optical waveguide so that one can easily see patterns. The total thickness and transparency of thin film displays are less than 100 um and over 90%, respectively.I. IntroductionFlexible displays are one of main issues in a display field. Most flexible display technologies have mainly focused on the active ones such as OLED and LCD. However, only a few efforts to passive signage displays have been made using LED sources or fluorescent lamps with a hard acrylic panel. Especially, flexible displays using optical waveguide are almost rare. Only two optical waveguide type displays have been considered using an optical fiber and polymer waveguide.[1] First one is constructed by guiding laser light through an optical fiber arranged in a spiral manner. The light leaks out via the grooves fabricated on the optical fiber. Second one is a polymer waveguide with successive branches which distribute the optical power from a laser to two-dimensional emission points on a plane. Therefore, it is necessary to develop thin, transparent, and flexible displays for signage. II. Experiment The overall fabrication process is the following. First, the under clad and core polymers are spin-coated on a Si wafer and cured by UV, respectively. Second, optical waveguide and scatters are formed by photolithography and reactive ion etching (RIE) process. Third, the upper clad polymer is spin-coated on the optical waveguide and cured. Finally, the polymer film is detached from the Si wafer.III. Results and discussionsThe principle of flexible signage display is the following. Light source is coupled into the optical waveguide, transferred to the scatters, and emitted to air as shown in Fig.1. If the thin film including the waveguide and scatters is an elastic polymer, the signage display could have a good flexibility.We used Bisphenol A ethoxylate diacrylate (Aldrich) and Tetra diacrylate (Aldrich) as core and clad, respectively. The refractive indices of BAED and TEGDA are 1.5647 and 1.5031 at 632nm, respectively. Under clad layer was spin-coated on Si wafer at 500 rpm for 20 seconds and uv-cured with 2 kW power for 5 minutes. The thickness of under clad layer was about 27 um. Core layer was spin-coated at 3700 rpm for 30 seconds and uv-cured with 2 kW power for 5 minutes. The thickness of core layer was about 15 um. After then, photolithography process has been done to make optical waveguide pattern on core layer with SU-8 photoresist (PR). SU-8 PR coated Si wafer was placed into RIE system to etch the core area without SU-8 PR. Since our Pdos20 process etched about 8um thickness of core layer, the etching process was done twice to etch 15um thickness of core layer. Core optical waveguide is finally made. Before making upper clad layer by spin coater, scatters have to be made in the core layer by using photolithography and RIE process. The scatters have a role to change the direction of light source from parallel to perpendicular to optical waveguide so that one can easily see pattern. If there are no scatters, light source is strictly guided within core layer and it is hard to see pattern that we want. Second photolithography process was done on core optical waveguide layer with SU-8 PR to make scatter pattern. SU-8 PR coated Si wafer was again placed into RIE system to etch small dot shaped scatter pattern. After developing SU-8 PR layer, upper clad layer was spin coated at 500 rpm for 20 seconds and uv-cured for 5 minutes. The thickness of upper clad layer was about 26um. The final thin film was detached on Si wafer. The total thickness of the film was about 70 um and the transparency was 91%. The thin film display was extremely bendable as shown in Fig.2. There was no light extraction loss even when the film was bended.In order to couple light source into our optical waveguide type display, we used a 4 ch single mode fiber block. Light source was 650 nm red LD with 50 mW. A 4 ch single mode fiber block and our display were placed on Auto-aligner system and attached with epoxy resin because 20um diameter core of single mode fiber has to be exactly placed to 15um core layer of our display to transfer light source into the display.

Reflection, Transmission and Diffraction Efficiencies in Homogenous Optical Thin Film and Grating Structures: An Overview

The matrix formalism is applied to describe various stratified and periodic systems that are used to couple optical energy into a dielectric film or medium. As the literature is often presenting cases for the transverse electric wave (TE), general analytical and numerical solutions are reviewed for many types of optical thin film systems with some emphasis on the transverse magnetic (TM) wave. This manuscript is divided into two main parts. In the first part, we look at stratified systems formed by a succession of multilayers and also present some applications for this type of optical systems such as bi-layer dielectric stacks. Tunneling across an air gap formed by two prisms’ long sides brought close to each other is also presented. Tunneling modes in optical system is reviewed in detail in systems that are probing an optical waveguide layer. In the second part of this manuscript, we are looking at optical systems in which a corrugated surface is used to couple energy into a medium. The matrix formalism used in this second part is applied mostly to grating waveguide structures and used in numerical computation of diffraction efficiencies (DE). Binary dielectric and metallic grating are also introduced with some emphasis on general ideas leading to the origin of photonic band-gap. This manuscript is reviewing various applications involving the matrix method supported by some results, but is also meant to be an overview with the main emphasis on optical thin film system grating waveguide structures.

Proton-exchanged optical waveguides in LiTaO3: phase composition and stress

Planar optical waveguide layers were obtained in Z-cut LiTaO3 crystal substrates via proton exchange. Two different media were used as proton sources: benzoic acid melt and lithium hydrogensulphate vapors, controlling the thickness of the waveguides by duration and temperature of the proton exchange process and also by post-exchange annealing. The intrinsic stress caused by the penetration of the hydrogen ions into the crystal lattice was estimated by the optical integral method. The phase composition of proton-exchanged layers was analyzed based on the mode and IR-absorption spectra. An attempt to relate the level of stress to the level of proton doping has been made.

Development of electro‐optical PCBs with polymer waveguides for high‐speed intra‐system interconnects

PurposeThe purpose of this paper is to study fabrication of optical‐PCBs on panel scale boards in a conventional modern PCB process environment. It evaluates impacts on board design and manufacturing with the developed optical board verifiers outlining challenges and requirements for manufacturing low‐loss waveguide structures and optical building blocks. The study aims to expand the current knowledge in the field by adding results obtained by utilizing industrial production infrastructure and developed scalable manufacturing processes to fabricate optical‐PCBs and board assemblies in high‐volumes and low‐cost manner.Design/methodology/approachImpacts on board design and manufacturing were studied with the developed optical technology verifiers. One verifier is optical‐PCB with embedded waveguides, integrated i/o couplers and optical vias. Another verifier is large size PCB with optical layer. A system‐level optical board assembly with 12.5 Gb/s Tx/Rx devices on surface mounted ball grid array (BGA) modules is designed for optical link analysis. Fabricated optical structures on verifiers are evaluated of their physical characteristics utilizing optical, SEM, LSCM analysis methods. Performance testing is conducted using standard optical transmission measurement methods and equipment.FindingsThe paper provides empirical results about fabrication of multimode optical waveguides with conventional PCB process equipment. Results suggest that current coating and imaging equipments are capable of producing optical waveguide patterns with high resolution and size accuracy. However, fabricators would require larger process window and defect tolerance for processing optical materials to obtain low‐loss waveguides with sufficient yields.Research limitations/implicationsBecause of the limited amount of design variants in production verifiers evaluated in this paper, some impacts like effect of base material, board construction, optical layer location and beam coupling solution were not evaluated. Likewise, impacts on long‐term stability and cost were not addressed. These factors however require further investigation to address technical feasibility of optical PCBs technology prior commercial high volume production.Practical implicationsThe paper includes implications for the development of a fabrication methods and testing procedures for optical polymer waveguide layers on PCBs.Originality/valueThis paper fulfils need to provide results on design, fabrication and characterization of optical PCBs and backplanes from industrial fabricator's perspective. The paper provides input for end‐user and developers to evaluate technical performance, robustness, and maturity of building blocks and supply chain to support polymer waveguide based technology for intra‐system optical links.

The Use of Vacuum Deposition for Fabrication of Optical Amplifying Mediums and Fiber Optic Modules

There has shown new vacuum technique of making planar waveguides doped with rare earths, on the basis of simultaneous vacuum deposition of quartz and alloying components. This technology allows to create optical waveguiding layers and amplifying planar compositions on wafers of silicon or quartz, and allows the dose-doping quartz with rare-earth elements, as well as germanium oxide and aluminum oxide, to obtain the optimal composition of a planar waveguide. With the help of lithography formed planar guide mediums with amplifying and modulating properties. There have been researched the methods of production of laboratory models of optical amplifying mediums, using vacuum technology, for the manufacture of planar erbium-doped amplifiers.

The Use of Vacuum Deposition for Fabrication of Optical Amplifying Mediums and Fiber Optic Modules

There has shown new vacuum technique of making planar waveguides doped with rare earths, on the basis of simultaneous vacuum deposition of quartz and alloying components. This technology allows to create optical waveguiding layers and amplifying planar compositions on wafers of silicon or quartz, and allows the dose-doping quartz with rare-earth elements, as well as germanium oxide and aluminum oxide, to obtain the optimal composition of a planar waveguide. With the help of lithography formed planar guide mediums with amplifying and modulating properties. There have been researched the methods of production of laboratory models of optical amplifying mediums, using vacuum technology, for the manufacture of planar erbium-doped amplifiers.

Relative power loss of misalignment based on electro-optical printed circuit board

In this paper, the power loss values between 45° total internal reflecting waveguide mirror (TIRWM) and the polymer optical waveguide layer are obtained by vector finite element method. There are some misalignments during an actual fabrication of electro-optical printed circuit board (EOPCB). And, b , a , c correspond to the error value of alignment in the x-axis, y-axis and z-axis direction, respectively. Another, four effective refractive indices of the 45° TIRWM and polymer optical waveguide layer are calculated, separately. And, n eff1 = 1.425211 is uniquely chosen. Next, these relative power errors Δ are calculated, when a , b , c separately change. Moreover, these error values are plotted into some curved surface figures. By these figures, it is easy to find the relationship between a , b , c and Δ. Furthermore, it is beneficial for us to avoid the region of larger power loss during an actual fabrication of EOPCB.

Modeling of injection characteristics of polar and nonpolar III-nitride multiple quantum well structures

Carrier confinement and injection characteristics of polar and nonpolar III-nitride quantum well (QW) light-emitting diode or laser diode structures are compared. We demonstrate that strongly inhomogeneous QW injection in multiple-QW (MQW) active region is one of the possible reasons holding back the advance of nonpolar laser structures. In polar structures, strong interface polarization charges induce the nonuniform carrier distribution among the active QWs so that the extreme p-side QW always dominates the optical emission. On the contrary, in nonpolar MQW structures, the inhomogeneity of QW populations is supported mainly by QW residual charges and the prevailing QW is the one closest to the n-side of the diode. For both polar and nonpolar structures, the QW injection inhomogeneity is strongly affected by the QW carrier confinement and becomes more pronounced in longer wavelength emitters with deeper active QWs. We show that in nonpolar structures indium incorporation into optical waveguide layers improves the uniformity of QW injection. On the contrary, QW injection in polar structures remains inhomogeneous even at high-indium waveguide layer compositions. We show, however, that polarization-matched design of the electron-blocking layer can noticeably improve the injection uniformity in polar MQW structure and enhance the structure internal quantum efficiency.

PDMS-based optical waveguide layer for integration in electrical–optical circuit boards

This paper reports on the optical properties of polydimethylsiloxane (PDMS) as a high-performance optical material system for optical interconnects. It is shown that optical PDMS layers laminated into printed circuit boards meet the requirements for low cost, low loss (0.06 dB/cm at 850 nm), high temperature ( > 290 ∘ C ) stable and mechanically robust electrical–optical circuit boards. A first production line for optical waveguide layers will be discussed.

Optical determination of three-dimensional nanotrack profiles generated by single swift-heavy ion impacts in lithium niobate

Three-dimensional (3D) profiles of single nanotracks generated by a low impact density of Cl ions at 46MeV have been determined by optical methods, using an effective-medium approach. The buried location of the maximum stopping power induces a surface optical waveguiding layer even at ultralow fluences (1011–1013at.∕cm2) that allows to obtain the effective refractive index profiles (from dark-mode measurements). Combining the optical information with Rutherford backscattering spectroscopy/channeling experiments, the existence of a surrounding defective halo around the amorphous track core has been ascertained. The 3D profile of the halo has also been determined.

A single regrowth integration platform for photonic circuits incorporating tunable SGDBR lasers and quantum-well EAMs

A monolithic integration platform is demonstrated for high functionality photonic circuits that include quantum-well electroabsorption modulators, semiconductor optical amplifiers, and widely tunable lasers. The platform is based on the selective removal of a set of active quantum wells located above an optical waveguide layer. The waveguide layer contains a second set of quantum wells to be used in modulator regions. Fabrication requires only a single blanket InP regrowth

Growth of thin AlInN∕GaInN quantum wells for applications to high-speed intersubband devices at telecommunication wavelengths

In this article, we report on growth of AlInN∕GaInN multi-quantum-wells (MQWs) with high Al content (93%) by rf-plasma-assisted molecular-beam epitaxy on (0001) GaN/sapphire templates and on bulk GaN crystals. A series of samples with a barrier thickness of 3nm and with different well thicknesses of 1.5–3nm was grown. The wells were doped with Si at a concentration of 5×1019cm−3. Structures grown on (0001) GaN-based substrates are crack-free, as demonstrated by Nomarski contrast and scanning electron microscopy measurements. X-ray diffraction mapping of a and c lattice parameters shows that AlInN∕GaInN MQWs are fully strained and have up to 7% indium in the barriers and up to 10% In in the quantum wells. These structures exhibit intersubband absorptions at room temperature at a wavelength in the range of 2.45–1.52μm. The AlInN∕GaInN strain-compensated MQW structures, having good quality, are very attractive for ultrahigh-bit-rate telecommunication applications at 1.55μm wavelengths. In addition, because of their low average refractive index, they could be used as thick cladding layers for optical waveguides.

Fabrication of inorganic–organic hybrid films for optical waveguide

Inorganic–organic hybrid guiding and buffer layers for optical waveguides were synthesized by the sol–gel process. An acid-catalyzed solution of 3-(trimethoxysilyl)propylmethacrylate and tetraethylorthosilicate was used as a precursor to produce thick films by spin-coating. Incorporation of a UV-sensitive functional group leads to the fabrication of the photo-patternable guiding layer. High-resolution patterned films with 8μm linewidth were obtained using a conventional photo-lithography. Furthermore, the amount of phenyltrimethoxysilane added as a refractive index modifier varied in order to control the refractive index of the underlying buffer layer. The refractive index variations and structural changes of these inorganic–organic hybrid films as a function of the processing conditions were analyzed using the prism coupling technique and a Fourier transform infrared spectrometer. We have produced optically transparent films at above 500nm with a propagation loss of 0.84 and 1.49dB/cm at 1310 and 1550nm, respectively.