The surface-enhanced Raman spectroscopy (SERS) activity and the optical reflectance of a subwavelength gold nanograting fabricated entirely using top down technologies on silicon wafers are presented. The grating consists of 120 nm gold cladding on top of parallel silica nanowires constituting the grating's lines, with gaps between nanowires <10 nm wide at their narrowest point. The grating produces inordinately intense SERS and shows very strong polarization dependence. Reflectance measurements for the optimized grating indicate that (when p-polarization is used and at least one of the incident electric field components lies across the grating lines) the reflectance drops to <1% at resonance, indicating that essentially all of the radiant energy falling on the surface is coupled into the grating. The SERS intensity and the reflectance at resonance anticorrelate predicatively, suggesting that reflectance measurements can provide a nondestructive, wafer-level test of SERS efficacy. The SERS performance of the gratings is very uniform and reproducible. Extensive measurements on samples cut from both the same wafer and from different wafers, produce a SERS intensity distribution function that is similar to that obtained for ordinary Raman measurements carried out at multiple locations on a polished (100) silicon wafer.

Large-area, 100mm in diameter, aluminum nanowire grids with 40nm line/78nm space were fabricated with full-wafer immersion interference lithography. The aluminum nanowire grids with a 59nm half-pitch work as a highly efficient optical polarizer for deep ultraviolet wavelength down to ∼250nm. In addition, an extremely high contrast from 10 000:1 to 50 000:1 was achieved across the whole visible and near-infrared wavelength range, along with good transmittance (85%–90%). The broadband large-area high-performance polarizer operating down to deep ultraviolet wavelength opens up applications including semiconductor lithography and metrology applications.

We report optical devices based on monolithic integration of multiple nano-structured optical functional layers. Ultraviolet (UV)-nanoimprint lithography along with thin-film deposition, high aspect-ratio reactive ion etching (RIE) and trench-filling technologies were used in fabrication and integration of individual nano-structured optical functional layers. Structures with sub-50 nm linewidth were required in order to achieve good optical performance in the near-UV and visible wavelengths. The ability to integrate multiple nanostructure-based optical layers opens a path for novel integrated optical devices, as well as a new strategy for driving both miniaturization and cost.

Both high contrast and high transmittance are preferred for optical polarizers. To achieve high transmittance for aluminum nanowire-grid polarizers, a narrow linewidth is required. In this letter, aluminum nanowire-grid polarizers with 30-nm-wide linewidth and 200nm depth were fabricated by UV-nanoimprint lithography, which leads to ultrahigh transmittance. To achieve a high contrast, the authors fabricated the 30-nm-wide aluminum nanowire structures on both sides of the glass wafers. An extremely high contrast up to 10 000:1 was achieved, in the visible range, along with good transmittance of 83%–87% for the double-side aluminum nanowire-grid polarizers.

We wrapped 150 nm period aluminum wire grid polarizer (WGP) with AlSiOx by using atomic layer deposition at 250 degrees C. The nanometer precision coating defined the spacer to double the spatial frequency of the 100 mm diameter grating fabricated by using a legacy immersion holography setup at 351 nm wavelength. Half-pitch grating of approximately 38 nm was demonstrated with good pattern uniformity, excellent repeatability, and a wide processing window. We believe 10 nm half-pitch grating over even larger areas are viable, overcoming one major hurdle to commercialize nanoimprint.

We design and fabricate polarization-dependent components (PDCs) based on all-dielectric, fully planarized, multilayer microstructures of 150 nm period by using low-loss materials. Quarter-wave and half-wave phase plates at 405 nm are presented. Multifunction integrated diffractive PDCs are discussed

We investigated two methods for imprinting metrology according to optical reflectance and transmittance of the imprinted substrates. We utilized the reflectance of two polarization states at 780nm for ∼100-nm polymer features with depth/width ratios>≈1 imprinted on ten 100-mm Si wafers. We not only successfully extracted the grating width, height, and residual polymer layers of the imprint but also assessed the uniformity and defects, as well as the aging of the templates from the same data. For transparent substrates, the optical test at shorter wavelengths clearly demonstrated a process monitor with 5-nm depth resolution for gratings of periods at 150nm with direct applicability to periods less than 50nm.

We successfully fabricated a high-performance half-wave plate for the 405 nm wavelength based on monolithic integration of two nanograting layers. Each of the nanograting layers functions as a quarter-wave plate. Both of the nanograting layers were fully filled and planarized to achieve the monolithic integration. UV-nanoimprint lithography, along with thin-film deposition, high-aspect-ratio reactive ion etching, and trench-filling technologies, was used in fabrication and integration of the individual nanograting layers. High-aspect-ratio nanogratings with sub-50 nm linewidths and 100 nm spacing were fabricated to achieve good optical performance at the near-UV wavelength. The ability to integrate multiple nanostructure-based optical layers opens a path for integrated multifunction devices, as well as a new strategy for driving both miniaturization and cost.

The authors have developed a nanomanufacturing platform based on wafer-level nanoreplication with mold and nanopattern transfer by nanolithography. The nanoreplication process, which is based on imprinting a single-layer spin-coated ultraviolet (UV)-curable resist, achieved good nanopatterning fidelity and on-wafer uniformity with high throughput. Some manufacturing issues of the nanoreplication process, such as the impact of wafer and mold surface particles on nanoreplication yield, are also discussed. Nano-optic devices, such as, quarter-wave plates and polarizers, were manufactured with the nanomanufacturing platform. An average wafer-level optical performance yield of 86% was achieved. The developed technology is applied for high-throughput and low-cost manufacturing nanostructure-based optical devices and integrated optical devices.

We developed various optical devices and integrated optical devices based on innovative nano-optical structures and design. The nano-optical devices and integrated devices were fabricated through a nano-manufacturing platform based on wafer level nano-replication with mold and nano-pattern transfer by nano-lithography. The nano-replication process, which based on imprinting a single-layer spin-coated UV curable resist, achieved excellent nano-patterning fidelity and on-wafer uniformity with high-throughput. Excellent wafer level performance and yield were achieved. Nano-optic devices, such as, quarter wave plates and polarizers, and integrated nano-optical devices, such as monolithically integrated semi-isolators, were manufactured with the nano-manufacturing platform. The developed technology is suitable for high-throughput and low cost manufacturing needs for commercializing nano-structure based optical devices and integrated optical devices.

We developed an integrated circular polarizer based on stacking an aluminum nano-wire grid polarizer with a dielectric nano-grating-based quarter waveplate. The polarizer consists of 65 nm wide and 130 nm tall aluminum wires with a period of 148 nm. For integration, the aluminum nanowires were buried into a silicon dioxide matrix by a trench filling and planarization technology. The buried nanowire polarizer achieved excellent optical performance in a broad wavelength range from 400 nm to >900nm. On top of the buried and planarized nanowire polarizer, a visible quarter waveplate based on a 200 nm period silicon nitride nano-grating was fabricated. Both the 148 nm period aluminum grating and the 200 nm period silicon nitride grating were fabricated by an ultraviolet (UV)-nanoimprint lithography. The ability to integrate multiple nanostructure-based optical layers opens a path for novel integrated optical devices, as well as a new strategy for driving both miniaturization and cost.

Atomic layer deposition, a highly uniform and conformal deposition process, was utilized to fill trenches of various high aspect-ratio nano-grating structures. Dielectric (e.g., SiO2), metal (e.g., aluminum), and dielectric/metal (e.g., Au∕SiO2) hybrid nano-gratings with a linewidth down to <50nm and an aspect ratio up to 14:1 (700nm:50nm) were trench-filled with various materials particularly nano-laminate materials such as TiO2∕SiO2 and SiO2∕Al2O3. Various high-performance optical devices such as true-zero-order optical retarders (i.e., wave plates) and nanowire-grid polarizers were realized based on an UV-nanoimprint lithography process and the atomic layer deposition for trench fillings. Thanks to both unique material properties and nano-structure trench filling capability, the atomic layer deposition opens a path for innovative nano-structure based optical devices and integrated optical devices.

Commercial quality high-performance true zero-order quarter waveplates based on artificial dielectric nanostructures were made by high throughput and low cost wafer-based nanofabrication processes. Both precise phase retardation (90°±2° across a 100mm-in-diameter glass wafer) and a high transmittance (>98.8%) were achieved. The quarter waveplates with different center wavelengths, such as, 780nm and 660nm, have been fabricated for optical pick-up (CD/DVD) applications. The nanostructure based true zero-order quarter waveplates are operational at a large wavelength and temperature range under a wide incident angle. The developed high quality true zero-order quarter waveplates have the potential for many cost-sensitive optical applications. Furthermore, it opens the potential for integrated optical applications thanks to the nanofabrication processes.

We developed a new type of wire-grid polarizer, the so-called nanowire-grid polarizer, which has achieved commercial quality optical performance and reliability, The nanowire-grid polarizer has cores composed of silicon dioxide nanowalls with metal coating on one side. These cores are surrounded by multilayer thin films for antireflection. The core nanowire grid utilizes nano-sized high-aspect ratio dielectric walls as a support for forming a high aspect ratio metal nanowire grid, which significantly reduces energy loss due to metal absorption for the transmitted beam While achieving high extinction ratio for the blocked beam. For all design simulations, we utilized a rigorous coupled-wave analysis and modal method. The nanowire-grid structure was fabricated by a wafer-based nanoreplication lithography and pattern-transfer techniques, which are capable of producing a large-area high aspect ratio nanostructure with high throughput and low cost. The optical performance of the nanowire-grid polarizer was characterized thoroughly. Furthermore,. the nanowire-grid polarizer has been integrated monolithically with a Faraday magnetooptic garnet, which results in an integrated semi-isolator. Full free-space isolators based on the integrated semi-isolators have been also developed, which achieved excellent performance, good enough for commercial applications.

Aluminum nanowire-grid polarizers and polarizing beam splitters with a fixed pitch (i.e., period) of ~146 nm but a wide range of linewidths (from < 60 nm to 90 nm) and heights (from 150 nm to 200 nm) are studied. Immersion interference lithography, UV-nanoimprint lithography and aluminum reactive ion etching were used to fabricate the nanowire-grid polarizers. Optical performance of the nanowire-grid polarizers was characterized in a broad spectral range from UV (< 400 nm) to near infrared (> 1700 nm). The performance trade-off between transmittance/reflectance and extinction ratio is investigated in details. The developed high-performance large-area broadband nanowire-grid polarizer opens the potential for many optical applications particularly integrated optics.

Lithographically defined optical nanostructures can be used to design various fundamental optical functions, including polarization, phase, refraction, and wavelength management. This paper describes the design, fabrication, and manufacturing of free-space discrete and integrated optical devices based on optical nanostructures. These devices are fabricated using a nanomanufacturing platform based on wafer-level nanoreplication with mold and nanopattern transfer by means of nanolithography. The nanoreplication process, based on imprinting a single-layer spin-coated ultraviolet (UV)-curable resist, achieved excellent nanopatterning fidelity and on-wafer uniformity with high throughput. It also achieved excellent wafer-level performance and yield. Nano-optical devices (NODs) (e.g., infrared polarizers and true zero-order quarter waveplates) and integrated NODs (e.g., monolithically integrated semi-isolators and visible circular polarizers) may be fabricated using the nanomanufacturing platform. The developed technology is suitable for the high-throughput and low-cost manufacturing needed to commercialize nanostructure-based optical devices and integrated optical devices. The success of the developed nano-engineering technology will lead to a redefinition of optical device manufacturing and integration and the functional and economic displacement of traditional bulk-optics devices.

We investigate a viable manufacture method of large area transmission only polarizers (TOPOL). A multilayer, mixed-scale (nanostructures and microstructrures) design is presented to accomplish the required functional integration. The effective domain of the device is less than 2 μm in thickness. Nanoimprint and UV lithography is combined to demonstrate the viable fabrication processes with 100 mm diameter wafers. The proposed structures can be further integrated. We also present detailed comparisons of the integrated devices with high-performance commercial-grade bulk optics.

We developed a new type of wire-grid polarizer that has achieved excellent optical performance and reliability. The nanowire-grid polarizer is based on a fully optimized innovative design structure that consists of not only the core nanowire grid but also the surrounding multilayer thin-film structures. The surrounding structures are designed for antireflectivity to provide the best possible efficiency as well as for device reliability to provide the best possible handling robustness and environmental durability. The core nanowire grid utilizes nanosized high-aspect-ratio dielectric walls as a support for forming a high-aspect-ratio metal nanowire grid that significantly reduces energy loss as a result of metal absorption for the transmitted beam while providing a high extinction ratio of the blocked beam. The developed high-quality nanowire-grid polarizer has potential for use in many integrated optical applications.

High-performance true zero-order optical retarders were realized based on all-dielectric immersion nanogratings. All-dielectric nanolaminate materials, deposited by atomic layer deposition, were utilized to fill the trenches of the nanogratings to form immersion nanogratings. The refractive index of the nanolaminate material can be dialed and controlled precisely by controlling the ratio of the two compositions forming the nanolaminate material. This significantly improves the design and process windows for realizing precise optical retarders, particularly very-low-phase retarders. Three 100-mm-diameter very-low-phase retarders with highly precise and uniform phase retardance and very high transmittance were realized by use of the all-dielectric immersion grating design and an atomic layer deposition technique.