Fabrication Of Waveguides Research Articles

One-dimensional and two-dimensional Er3+-doped germanate glass waveguides by combination of He+ ion implantation and precise diamond blade dicing

Compact and miniaturized Er3+-doped waveguide structure is an important research direction in integrated optics. In this work, the Er3+-doped germanate glass was bombarded by a 400-keV He+ ion beam with a fluence of 6.0 × 1016 ions/cm2 for the formation of the one-dimensional waveguide in a vacuum. Subsequently, the precise diamond blade with a rotating velocity of 20,000 rpm and a cutting speed of 0.1 mm/s was applied to dice the surface of the one-dimensional waveguide for the fabrication of the two-dimensional structure. The formation mechanism and the refractive index profile of the one-dimensional waveguide were studied by the SRIM 2013 and the RCM, respectively. The electromagnetic field profiles for the fundamental modes of both one-dimensional and two-dimensional waveguides were measured by the end-face coupling method. It presents some useful information in the field of fabrication and characterization of optical waveguides for active photonic applications.

Ultrafast laser writing of arbitrary long low-loss waveguides in optical fibers.

We propose an innovative femtosecond laser writing approach, based on a reel-to-reel configuration, allowing the fabrication of arbitrary long optical waveguides in coreless optical fibers directly through the coating. We report few meters long waveguides operating in the near-infrared (near-IR) with propagation losses as low as 0.055 ± 0.004 dB/cm at 700 nm. The refractive index distribution is shown to be homogeneous with a quasi-circular cross section, its contrast being controllable via the writing velocity. Our work paves the way for the direct fabrication of complex arrangements of cores in standard and exotic optical fibers.

Method for parallelism measurement of geometrical waveguides based on the combination of an autocollimator and a testing telescope.

Augmented reality (AR) is desperately needed in the Metaverse. The geometrical waveguide receives increased attention in AR technology as achieving high resolution, full-color display, etc. However, the stray light and ghost image problems resulting from the parallelism errors severely deteriorate the imaging quality. According to the light propagation of the waveguide, a measuring system based on the combination of the autocollimator and the testing telescope (CAT) method was proposed to measure the parallelism errors of the partially reflective mirror array (PRMA). The results indicated that this method could measure the parallelism errors precisely with the maximum repeatability of 0.63 ' ' . The method could decouple the coupling of the parallelism errors of the PRMA and the substrate surfaces to imaging quality effectively. The precise parallelism measuring is expected to contribute to mass production and low cost by promoting the waveguide design and fabrication.

Low-loss optofluidic waveguides in fused silica enabled by spatially shaped femtosecond laser assisted etching combined with carbon dioxide laser irradiation

We demonstrate the fabrication of low-loss optofluidic waveguides encapsulated in fused silica glass using femtosecond laser microfabrication followed by carbon dioxide laser irradiation. Spatially-shaped femtosecond laser-assisted chemical etching is first used to fabricate microchannels with circular cross-sections and a string of open extra-access ports in the glass. Further, the carbon dioxide laser direct writing on the glass surface is used to create a thermal reflow effect of etched glass microstructures for simultaneously polishing all internal surfaces of channels and sealing the extra-access ports. With this effect, the inner surface roughness of the etched microchannels can be reduced to ∼ 40 nm. Finally, a single-mode microfluidic optical waveguide with a propagation loss of ∼ 0.78 dB/cm at 1310 nm is obtained inside the glass by filling a mixture solution of decane and liquid paraffin into a laser-polished microchannel.

Fabrication and Characterization of Core Offset Waveguide Optical Sensor for Refractive Index Measurement

<p>Refractive index is important parameter in various fields, such as environmental, chemical, industrial, and medical. Measurement of refractive index can be done using optical sensor based buried waveguide core offset. This research aims to fabricate and characterize core offset buried waveguide based on <em>Polymethyl Methacrylate </em>(PMMA). Fabrication of buried waveguide was done by creating a cladding of waveguide made from PMMA which has a refractive index of 1.4908 using computer numerical Control machine (CNC). The material used as waveguide core was unsaturated polyester resin (UPR). Characterization was performed to determine the spectrum of input intensity and output intensity. Characterization were done by dipping the waveguide sample in to a container containing glucose solution with concentration of 12%, 14%, 16%, 18%, 20%, and 24%. Waveguide was connected to Polymer Fiber Optic (POF). One of the of POF as an input is connected to light emited diode with wavelength of 470 nm and one of the end other POF as an output was connected to Spectrometer Ocean Optic USB4000. The result showed that the total loss at concentration of 12%-24% is -4.62 dB, -5,70 dB, -6,01 dB, -6,49 dB, -6,15 dB, -6,16 dB, respectively. Sensor works well at a solution concentration of 16%-20% with a sensitivity value of 19.62 dB/RIU and correlation factor of 92.76%.</p><p> </p>

Facile fabrication and optical properties of polymer waveguides with smooth surface for board-level optical interconnects

Facile fabrication and optical properties of polymer waveguides with smooth surface for board-level optical interconnects

Infrared LiF ridge waveguide fabricated by carbon ion irradiation

We report on the fabrication of an optical ridge waveguide in lithium fluoride crystal using the method of C5+ ion irradiation with precise diamond blade dicing. The guiding properties of the waveguide at the infrared wavelengths of 1064 nm, 2200 nm and 4000 nm are investigated in detail. All the near-field modal profiles exhibit single-mode guidance and the minimum propagation losses of the ridge waveguide after annealing are reduced to 0.7 dB cm−1 (λ = 1064 nm), 0.4 dB cm−1 (λ = 2200 nm) and 0.2 dB cm−1 (λ = 4000 nm), respectively. The Raman spectroscopy of the waveguide shows that the ion irradiation does not obviously change the lattice structure of the crystal.

Mode characteristics of a graphene-coated cylindrical dielectric waveguide with a nested eccentric hollow elliptical cylinder

A cylindrical dielectric nanowire waveguide embedded with an eccentric hollow elliptical cylinder is designed. The mode characteristics of the first three modes supported by the waveguide are studied by the multipole method and verified by the finite element method. Results show that the waveguide has the best transmission performance when the symmetric center of the hollow elliptical cylinder is located on the y axis of the cylindrical dielectric nanowire. The influence of the working wavelength, the Fermi energy, and the dielectric constant of region II on the transmission performance of the waveguide is great, while the influence of the semi-long axis, the semi-short axis of the elliptic cylinder, the radius of the cylinder, and the minimum distance between two rods on the transmission performance of the waveguide is less. Compared with the other waveguide structures, the waveguide introduced in this paper has a better overall transmission performance. This kind of waveguide can provide a theoretical basis for the design, fabrication, and application of graphene-coated nested nanowire waveguides.

How will challenges in micro- and nanofabrication impact the development of quantum technologies?

The development of useful quantum technologies will heavily rely on assembling many sub-systems that exhibit quantum properties. These systems do not spontaneously assemble themselves into useable quantum machines: they rely on advanced fabrication techniques at micro- and nanometre scales. Examples of such techniques include the fabrication of electrodes and waveguides for trapped ions, of Josephson junctions and microwave chips for superconducting circuits, of electrodes for the control of quantum dots or the fabrication of low-disorder semi-conductors for the operation of Majorana Zero Modes.

Single-mode SU-8 waveguide fabricated using ultrafast direct laser writing

In this work, we demonstrated the application of femtosecond laser direct writing using the two-photon polymerization (TPP) technique in the fabrication of single-mode optical waveguide in SU-8 photoresist. It was found that the polymerization of SU-8 using 780 nm femtosecond laser requires a fluence of 1.8–10 kJ/cm2, where 2.5 kJ/cm2 is sufficient to create a flat-top surface waveguide for a 1.8 µm thick SU-8 film. To reduce the coupling loss of the waveguide, the waveguide width was enlarged with double scan of the femtosecond laser by shifting the sample laterally with a center-to-center spacing of 0.5 µm between scans. The optimized waveguide has an insertion loss of 11 dB, with an approximated propagation loss of 1.27 dB/cm. Based on the information obtained, a directional coupler was fabricated. The resulting coupling ratio of the directional coupler is 47 % and 53 % at each port. To further demonstrate the viability of the proposed technique to fabricate complex waveguide structures, a vertically suspended waveguide has been designed and fabricated.

Ultrafast laser inscribed waveguides in tailored fluoride glasses: an enabling technology for mid-infrared integrated photonics devices

Zirconium fluoride (ZBLAN) glass, the standard material used in fiber-based mid-infrared photonics, has been re-designed to enable the fabrication of high index-contrast low-loss waveguides via femtosecond laser direct writing. We demonstrate that in contrast to pure ZBLAN, a positive index change of close to 10−2 can be induced in hybrid zirconium/hafnium (Z/HBLAN) glasses during ultrafast laser inscription and show that this can be explained by an electron cloud distortion effect that is driven by the existence of two glass formers with contrasting polarizability. High numerical aperture (NA) type-I waveguides that support a well confined 3.1 μm wavelength mode with a mode-field diameter (MFD) as small as 12 μm have successfully been fabricated. These findings open the door for the fabrication of mid-infrared integrated photonic devices that can readily be pigtailed to existing ZBLAN fibers.

Low-Frequency Terahertz Photonic Crystal Waveguide with a Lilac-Shaped Defect Based on Stereolithography 3D Printing

Terahertz (THz) photonic crystal (PC) waveguides show promise as an efficient and versatile waveguiding platform for communication, sensing, and imaging. However, low-frequency THz PC waveguides with a low-cost and easy fabrication remain challenging. To address this issue, a THz PC waveguide with a lilac-shaped defect has been designed and fabricated by 3D printing based on stereolithography (SLA). The reflection and transmission characteristics of the proposed waveguide have been analyzed using the finite difference frequency domain (FDFD) method. The waveguide spectral response is further optimized by changing the distance of the lilac-shaped resonant cavities. Consistent with the results of numerical modeling, the measured results show that the waveguide performs a resonant reflection in the region of 0.2 to 0.3 THz and low-pass transmission in the 6G mobile communication window. Furthermore, in order to characterize the performance of the proposed waveguide, parameters have been analyzed, including the Q factor, resonant frequency, and bandwidth. This work supplies a novel pathway for the design and fabrication of a low-frequency THz PC waveguide with potential applications in communication, sensing, and imaging.

Characterisation of Channel Waveguides Fabricated in an Er3+-Doped Tellurite Glass Using Two Ion Beam Techniques

Two methods were proposed and implemented for the fabrication of channel waveguides in an Er-doped Tellurite glass. In the first method, channel waveguides were fabricated by implanting 1.5 MeV and 3.5 MeV energy N+ ions through a special silicon mask to the glass sample at various fluences. Those waveguides implanted at a fluence of 1.0 × 1016 ions/cm2 operated up to 980 nm, and showed green upconversion of the Erbium ions. In the second method, channel waveguides were directly written in the Er3+: TeO2W2O3 glass using an 11 MeV C4+ ion microbeam with fluences in the range of 1 · 1014–5 · 1016 ions/cm2. The waveguides worked in single mode regime up to the 1540 nm telecom wavelength. Propagation losses were reduced from the 14 dB/cm of the as-irradiated waveguides by stepwise thermal annealing to 1.5 dB/cm at λ = 1400 nm.

Surface Lattice Plasmon Resonances by Direct In Situ Substrate Growth of Gold Nanoparticles in Ordered Arrays.

Precise arrangements of plasmonic nanoparticles on substrates are important for designing optoelectronics, sensors and metamaterials with rational electronic, optical and magnetic properties. Bottom-up synthesis offers unmatched control over morphology and optical response of individual plasmonic building blocks. Usually, the incorporation of nanoparticles made by bottom-up wet chemistry starts from batch synthesis of colloids, which requires time-consuming and hard-to-scale steps like ligand exchange and self-assembly. Herein, an unconventional bottom-up wet-chemical synthetic approach for producing gold nanoparticle ordered arrays is developed. Water-processable hydroxypropyl cellulose stencils facilitate the patterning of a reductant chemical ink on which nanoparticle growth selectively occurs. Arrays exhibiting lattice plasmon resonances in the visible region and near infrared (quality factors of >20) are produced following a rapid synthetic step (<10min), all without cleanroom fabrication, specialized equipment, or self-assembly, constituting a major step forward in establishing in situ growth approaches. Further, the technical capabilities of this method through modulation of the particle size, shape, and array spacings directly on the substrate are demonstrated. Ultimately, establishing a fundamental understanding of in situ growth has the potential to inform the fabrication of plasmonic materials; opening the door for in situ growth fabrication of waveguides, lasing platforms, and plasmonic sensors.

Ridge waveguide lasers with vertically stacked quantum wells and tunnel junctions

We report on the fabrication and electro-optical performance of ridge waveguide (RW) lasers emitting near 905 nm based on a vertical layer structure consisting of three single quantum wells (SQWs) as active regions separated by two tunnel junctions (TJs). The single waveguide core is designed in such a way that the third vertical mode is lasing. The width of the ridge is varied between 3 µm and 200 µm. Deep- and shallow-etched ridges were fabricated. The shallow etching stopped slightly above the topmost SQW, whereas the deep etch went through all TJs and stopped slightly above the lowest SQW. For comparison, we also fabricated conventional shallow-etched RW lasers based on a similar vertical structure having only one SQW and no TJs. The TJ RW lasers with deep-etched ridges provide the highest output power, lowest threshold current and best slope efficiency of 2.4 W A−1 for a ridge width of 6 µm. The performance of shallow-etched TJ RW lasers is lowest for small ridge widths but surpasses the performance of the conventional RW lasers when the ridge width is increased. The lateral far field angle of deep-etched TJ RW lasers is about 2° larger compared to the shallow etched ones.

Development of High Refractive Index Polydimethylsiloxane Waveguides Doped with Benzophenone via Solvent-Free Fabrication for Biomedical Pressure Sensing

We present the fabrication and characterization of elastomeric optical waveguides, to be used for the manufacture of a conformable, water-resistant, and cost-effective pressure sensor that is amenable to the development of smart wearable health monitoring devices. To achieve this goal, high-sensitivity polydimethylsiloxane waveguides with a rectangular cross-section were fabricated. A new up-doping procedure, to tailor the refractive index of the ensuing waveguides, was experimentally developed using benzophenone additives. With this method we demonstrated a high refractive index change (up to +0.05) as a linear function of the benzophenone doping concentration. Propagation losses of about 0.37 dB/cm in the visible range and a high sensitivity to transverse compression of 0.10%/dB optical power loss were measured. It was also shown that one can further control the refractive index of the waveguide core and cladding regions through proper selection of the polydimethylsiloxane base to curing agent mixing ratio.

Rapid automatic waveguide recognition using YOLO and OpenCV for 3D waveguide fabrication

A 3D waveguide is attractive because it has the potential that the waveguides are arranged, not only in plane, into three-dimension. The mosquito method, in which the core and cladding material sources are liquid and will be cured using UV light, is known as one of the ways to fabricate the 3D waveguide. In this method, if multiple waveguides are fabricated, the time until UV cure is different between the first waveguide and the last one and it leads to core position shift because of gravity. To solve the problem, we considered reducing the time from the first waveguide formation to the UV cure using automatic waveguide fabrication with a camera. For the automatic waveguide fabrication, YOLO (you look only once) and OpenCV are exploited as machine learning and an image processor, respectively. As a result, a waveguide recognition time of 10 ms and image processing time of 50 ms, totally 60 ms, are realized.

Fabrication and polarization modulation of waveguides in 4H-SiC crystals by femtosecond laser direct writing

Fabrication and polarization modulation of waveguides in 4H-SiC crystals by femtosecond laser direct writing

Metal droplet printing of tube with high-quality inner surface via helical printing trajectory and soluble support

ABSTRACT Metal droplet-based 3D printing provides unique advantages for fabricating micro complex parts. Especially, assisted by soluble support, structures with high-quality inner surfaces can be directly printed without post-processing, which is very promising for the fabrication of waveguides and antenna horns. Here, a spatially distributed equidistant helical deposition strategy with only one-step positioning was proposed to improve the inner surface quality of the parts, and a five-axis motion stage was designed for matching its motion planning. The influence mechanisms of key process parameters on the forming quality were investigated. The droplet positioning errors, the aggregation behaviour, and the hole-defects formation on sloping surfaces were analyzed. As a proof-of-concept, a horn-structured tube was directly printed via the proposed printing method, which possessed both high-quality cavity surfaces and high density. This work paves the route towards the efficient additive manufacturing of metal tubes with high-quality inner surfaces.

Integrated Subwavelength Gratings on a Lithium Niobate on Insulator Platform for Mode and Polarization Manipulation (Laser Photonics Rev. 16(7)/2022)

Subwavelength Gratings In article number 2200130, Yonghui Tian and colleagues experimentally demonstrate compact subwavelength grating (SWG) waveguides on a LNOI platform for on-chip mode and polarization manipulation. To overcome the limitation of direct etching waveguide fabrication, a silicon nitride thin film was deposited onto the surface of LNOI chip, where the SWGs were formed using CMOS-compatible etching processes developed by microelectronics industry.