Blazed gratings are widely used for surface relief grating (SRG) waveguides for augmented reality displays. To increase the efficiency and design freedom of blazed gratings the control of the anti-blaze angle has gained attention lately. We will demonstrate mastering processes to realize blazed gratings with positive, vertical and negative anti-blaze angles on masters for the replication of SRG waveguides.
Amidst the mixed news surrounding the feasibility of Augmented Reality (AR) smart glasses, the demand for commercially viable mass production of industry-standard optical waveguide combiners remains unwavering. Over the past two years, our consortium of companies has proposed a cost-effective and scalable manufacturing process for Surface Relief Grating (SRG) based waveguides, offering a comprehensive path from concept to fabrication through large-area nanoimprinting. This approach has garnered significant interest from both customers and partners associated with the participating companies. Our aim is to push beyond the established limits of large-area nanoimprinting. In this work we address the obstacles and latest advancements in maintaining imprint quality, fidelity and uniformity during large-area nanoimprinting. We demonstrate various building blocks that are crucial to manufacture high quality and cost-effective AR waveguides, such as the replication of slanted gratings and the possibility of low residual layer thickness using large-area nanoimprint lithography. We employ high refractive index materials, such as resin and glass (1.8, 1.9 and 2.0), and also explore a lighter and flatter version of the RealView 1.9 glass. Our primary objective is to demonstrate that large-area nanoimprinting not only presents itself as a novel method for high-volume manufacturing of SRG waveguides but also enables the production of challenging optics for AR smart glasses.
Nanoimprinting of surface-relief grating-based waveguides has the potential to produce one of the industry-leading augmented reality (AR) smart glasses, but there are still many challenges in the design, scaling, and reproducibility of these imprinted waveguides. A promising path toward mass manufacturing of optical waveguide combiners is via large-area nanoimprinting. Here, we present the complete value chain with partners involved throughout the process: from design, mastering, and materials to imprinting and metrology, to prove that this method improves not only the manufacturing throughput but also the waveguide quality. We demonstrate that the replication and image quality are true to the intended design using large area, high refractive index (n = 1.9), square (300 mm × 300 mm) glass substrates with high-refractive index resins (n = 1.9). This is shown to be valid for over 100 replications and for large area nanoimprinting (Gen5, 1100 mm × 1300 mm). Our goal is to demonstrate a viable path toward high-volume and low-cost manufacturing of AR waveguides based on surface relief gratings.
Nanoimprinting of surface-relief grating-based waveguides has the potential to result in the best performing Augmented Reality (AR) smart glasses, but there are still many challenges in the design, scaling, and reproducibility of these imprinted waveguides. We presented a promising path toward mass manufacturing of optical waveguide combiners via large-area nanoimprinting at SPIE AR/VR/MR 2022. This alternative route for manufacturing surface-relief gratings on a larger area generated much interest. This follow-up paper presents a further optimized design based on the lessons learned from the previous paper, with a particular focus on quality. The complete value chain with partners is involved throughout the process of this iterative update: from design, mastering, and materials to imprinting and metrology, to prove that this method improves not only the manufacturing throughput but also the waveguide quality. We demonstrate that both the replication and image quality is true to the intended design using large area, high refractive index (1.9 RI), square (300 x 300mm) glass substrates with high refractive index resins (1.9 RI). Our objective is to further establish this new approach towards high-volume and low-cost manufacturing of waveguides based on surface relief gratings as a viable path forward for enabling the Metaverse.
We present our latest developments and results in making meta optical elements (MOE) (also known as metalenses). MOEs are prototyped by electron beam lithography (EBL) and mass produced by nanoimprint lithography (NIL) ensuring a fast route from development phase to final products compared to DUV based supply chains. Furthermore, NIL has no constraints on meta-atom geometries (size, shape, and location) enabling the best performing metalenses. As a demonstrator a complete near-IR camera module is built using a 940 nm single metalens (1M) and a NIR sensor. Figure 4 shows and image recorded by such a near-IR imaging system. The recorded image shows excellent resolution all the way to the edge and is comparable to images captured with a multi-element refractive lens system. In general MOE lenses have significantly better image quality with a wide field of view, low F-number, high MTF, and high relative illumination, all at a low total track length. NIL Technology is designing, prototyping, assembling, and bringing up mass production of MOEs.
For more than a decade, camera lenses used in smartphones and other products have not seen revolutionary changes. Lenses are still made with multiple bulky refractive lenses or lens elements stacked on top of each other. NIL Technology is on a mission to bring revolutionary changes to smartphone cameras and sensors by significantly reducing the size and complexity of these lens systems.
Besides MOEs NIL Technology is also offering customized solutions and mass production of diffractive optical elements (DOEs) and microlens arrays (MLAs) and all three technologies can be combined in hybrid solutions when applicable. Furthermore, we supply masters for surface relief waveguides for augmented reality (AR).
Larger field of view, better image quality and higher efficiency in Augmented Reality (AR) glasses demands masters with large uniform diffraction gratings. Typically, a surface relief waveguide master is composed of input, output and deflection/expander gratings which all can either be slanted, blazed or binary gratings. Control of the angle of slanted and blazed gratings especially over large areas is an important parameter towards high quality large area gratings. Here we demonstrate large area diffraction gratings for AR applications where the angle uniformity is demonstrated to be +/- 1 degree across an 8-inch wafer. NIL technology has been pioneering the development of high quality large area slanted, binary and blazed grating masters and offers customizable solutions for all of the above-mentioned types of gratings and the gratings can be combined with 100% design freedom on the masters.
A promising path towards consumer electronics-ready manufacturing of optical waveguide combiners is via large-area nanoimprinted surface relief gratings on high index glass substrates. Presently, this is realized through equipment and substrates based on wafer format (up to 12-inch). In this work, we present a way to produce waveguides with surface relief gratings utilizing the entire value chain from design to mastering to replication on panel-level nanoimprint equipment using rectangular high refractive index glass substrates and high refractive index resins. This is demonstrated on a greater than Gen 3 panel size (550 mm x 650 mm). The fabricated waveguides are optically tested to validate the design and the value chain. We demonstrate that the quality of the large area imprints is similar to present wafer-level imprints. Thus, we introduce a new approach towards high volume and low-cost manufacturing of waveguides based on surface relief gratings.
To meet the demand for high quality augmented reality displays with larger field of view, large eye box and better image quality, large area diffraction gratings are needed. Across the industry different types of surface relief gratings for in-coupling and out-coupling are used in the waveguide designs to achieve the optimum performance of the waveguide. Typical gratings are slanted, blazed, binary and multi-level gratings. NIL Technology offers solutions for all of the above-mentioned types of gratings meeting the demand for high quality and size of in particular the output gratings from the market.
An optical two-beam trap, composed from two counter propagating laser beams, is an interesting setup due to the ability of the system to trap, hold, and stretch soft biological objects like vesicles or single cells. Because of this functionality, the system was also named "the optical stretcher" by Jochen Guck, Josep Käs and co-workers some 15 years ago. In a favorable setup, the two opposing laser beams meet with equal intensities in the middle of a fluidic channel in which cells may flow past, be trapped, stretched, and allowed to move on, giving the promise of a high throughput device. Yet, single beam optical traps, aka optical tweezers, by far outnumber the existing optical stretchers in research labs throughout the world. The ability to easily construct an optical stretcher setup in a low-cost material would possibly imply more frequent use of the optical stretching technique. Here, we will outline the design, the production procedures, and results obtained in a fiber-based experimental setup built within an injection molded microfluidic polymer chip. The microfluidic chip is constructed with a three layer technology in which we ensure both horizontal and vertical focusing of the cells we wish to trap, thereby preventing too many cells to flow below the line of focus of the two counter propagating laser beams that are positioned perpendicular to the direction of flow of the cells. Results will be compared to that from other designs from previous work in the group.
Maksim Zalkovskij, Lasse Thamdrup, Kristian Smistrup, Thomas Andén, Alicia Johansson, Niels Jørgen Mikkelsen, Morten Hannibal Madsen, Jørgen Garnæs, Tommy Tungelund Kristiansen, Mads Diemer, Michael Døssing, Daniel Minzari, Peter Torben Tang, Anders Kristensen, Rafael Taboryski, Søren Essendrop, Theodor Nielsen, Brian Bilenberg
In this paper, we present a route for making smart functionalized plastic parts by injection molding with sub-micrometer
surface structures. The method is based on combining planar processes well known and established within silicon micro
and sub-micro fabrication with proven high resolution and high fidelity with truly freeform injection molding inserts.
The link between the planar processes and the freeform shaped injection molding inserts is enabled by the use of
nanoimprint with flexible molds for the pattern definition combined with unidirectional sputter etching for transferring
the pattern. With this approach, we demonstrate the transfer of down to 140 nm wide holes on large areas with good
structure fidelity on an injection molding steel insert. The durability of the sub-micrometer structures on the inserts have
been investigated by running two production series of 102,000 and 73,000 injection molded parts, respectively, on two
different inserts and inspecting the inserts before and after the production series and the molded parts during the
production series.
Various nanostructures with a feature sizes down to 50 nm as well as photonic structures such as waveguides or grating
couplers were successfully replicated into the thermoplastic polymer polymethylpentene employing an injection molding
process. Polymethylpentene has highly attractive characteristics for photonic and life-science applications such as a high
thermal stability, an outstanding chemical resistivity and excellent optical transparency. In our injection molding process,
the structures were directly replicated from 2" silicon wafers that serve as an exchangeable mold insert in the injection
mold. We present this injection molding process as a versatile technology platform for the realization of optical
integrated devices and diffractive optical components. In particular, we show the application of the injection molding
process for the realization of waveguide and grating coupler structures, subwavelength gratings and focusing nanoholes.
We present a technology for miniaturized, chip-based liquid dye lasers, which may be integrated with microfluidic networks and planar waveguides without addition of further process steps. The microfluidic dye lasers consist of a microfluidic channel with an embedded optical resonator. The lasers are operated with Rhodamine 6G laser dye dissolved in a suitable solvent, such as ethanol or ethylene glycol, and optically pumped at 532 nm with a pulsed, frequency doubled Nd:YAG laser. Both vertically and laterally emitting devices are realized. A vertically emitting Fabry-Perot microcavity laser is integrated with a microfluidic mixer, to demonstrate realtime wavelength tunability. Two major challenges of this technology are addressed: lasing threshold and fluidic handling. Low threshold, in-plane emission and integration with polymer waveguides and microfluidic networks is demonstrated with distributed feed-back lasers. The challenge of fluidic handling is addressed by hybridization with mini-dispensers, and by applying capillary filling of the laser devices.
The integration of optical transducers is generally considered a key issue in the further development of lab-on-a-chip microsystems. We present a technology for the integration of miniaturized, polymer based lasers, with planar waveguides, microfluidic networks and substrates such as structured silicon. The flexibility of the polymer
patterning process, enables fabrication of laser light sources and other optical components such as waveguides, lenses and prisms, in the same lithographic process step on a polymer. The optically functionalised polymer layer can be overlaid on any reasonably flat substrate, such as electrically functionalised Silicon containing
photodiodes. This optical and microfluidic overlay, interfaces optically with the substrate through the polymer-substrate contact plane. Two types of integrable laser source devices are demonstrated: microfluidic- and solid polymer dye lasers. Both are based on laser resonators defined solely in the polymer layer. The polymer laser sources are optically pumped with an external laser, and emits light in the chip plane, suitable for coupling into chip waveguides. Integration of the light sources with polymer waveguides, micro-fluidic networks and photodiodes embedded in a Silicon substrate is shown in a device designed for measuring the time resolved absorption of two fluids mixed on-chip. The feasibility of three types of polymers is demonstrated: SU-8, PMMA and a cyclo-olefin co-polymer (COC) -- Topas. SU-8 is a negative tone photoresist, allowing patterning with conventional UV lithography. PMMA and Topas are thermoplasts, which are patterned by nanoimprint lithography (NIL).
The integration of optical transducers is generally considered a key issue in the further development of lab-on-a-chip Microsystems. We present a technology for miniaturized, polymer based lasers, suitable for integration with planar waveguides and microfluidic networks. The lasers rely on the commercial laser dye Rhodamine 6G as active medium, and the laser resonator is defined in a thin film of polymer on a low refractive index substrate. Two types of devices are demonstrated: solid and microfluidic polymer based dye lasers. In the microfluidic dye lasers, the laser dye is dissolved in a suitable solvent and flushed though a microfluidic channel, which has the laser resonator embedded. For solid state dye lasers, the laser dye is dissolved in the polymer forming the laser resonator. The miniaturized dye lasers are optically pumped by a frequency doubled, pulsed Nd:YAG laser (at 532 nm), and emit at wavelengths between 560 nm and 590 nm. The lasers emit in the plane of the chip, and the emitted light is coupled into planar polymer waveguides on the chip. The feasibility of three types of polymers is demonstrated: SU-8, PMMA and a cyclo-olefin co-polymer (COC) - Topas. SU-8 is a negative tone photoresist, allowing patterning with conventional UV lithography. PMMA and Topas are thermoplasts, which are patterned by nanoimprint lithography (NIL). The lasing wavelength of the microfluidic dye lasers can be coarse tuned over 30 nm by varying the concentration of laser dye, and fine tuned by varying the refractive index of the solvent. This is utilized to realize a tunable laser, by on-chip mixing of dye, and two solvents of different index of refraction. The lasers were also integrated with waveguides and microfluidic networks.
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