Flat optics is an emerging technology that uses nano-patterned surfaces designed to perform the same functions as bulk optical components. Applications for this exciting technology include 3D sensing, displays, AR / VR solutions, imaging, microscopy, holographic security and communications to name a few. These can be processed using industrially established micro- and nano-fabrication techniques. By carefully selecting the materials used and engineering the geometries correctly, solutions covering a wide range of frequencies from the visible spectrum to mid-infrared and beyond can be provided.
The core of the proposed flat optics technologies lies on the use of “dielectric nanoantennas”. These antennas are sub-wavelength sized particles whose geometry is engineered to provide flat optical components with extremely low absorption and high-efficiency standards. Work was carried out solely with dielectric and semiconductor materials. One common material is silicon, but oxides, nitrides, and III-V semiconductors can also be used.
The unique design capabilities allow the production of flat optical components that can perform virtually any functionality, often outperforming their traditional counterparts. One example is the proprietary, ultra-high-numerical-aperture flat lenses. These lenses, designed to have numerical apertures far larger than any commercial ones, exhibit focusing and resolving capabilities that approach the ultimate diffraction limit.
Technology Features, Specifications and Advantages
- Functionality by design: the unique approach proposed provides complete control of the local phase, amplitude and polarization of light with sub-wavelength resolution. Thus, the flat optical designs can realize virtually any desired function - from extremely high numerical aperture lenses to polarizers, wave retarders and more complex functionalities such as holographic phase masks and complex beam generation.
- Design flexibility: the proposed flat optics components can be designed to work under different illumination conditions as well as in reflection or transmission modes.
- Scalable operational wavelength: flat optics solutions for different spectral ranges are possible - from visible, to near-infrared and telecommunications, to mid-infrared and beyond.
- Suitable for mass production: the proposed designs account for fabrication constraints of state-of-the-art mass production foundries, limiting the minimum feature sizes and maximum aspect ratios of the geometries involved.
- Low absorption and high efficiency: the use of low absorption materials and the unique design approach allows the flat optics components to be world leading in terms of efficiency and performance.
- Broad range of materials: the designs can be adapted to a broad range of dielectric and semiconductor materials depending on the functionality requirements and frequency of operation. Materials include CMOS compatible ones such as silicon, oxides (e.g. TiO2), nitrides (e.g. SiN) and III-V semiconductors (e.g. GaN, GaP or InP).
Flat optics is a versatile technology platform with potential applications in a wide range of areas, depending on the functionality of the optical component. These include, but are not limited to:
- Imaging and microscopy: allowing ultra-compact optical systems in mobile phone cameras, head-mounted displays, and other space-constrained devices. For microscopy and inspection systems, it can provide resolution near the diffraction limit.
- Holography and complex beam shaping: providing high resolution and high-quality beams enabled by sub-wavelength pixel size, allowing compact integration with VCSELs and other light sources.
- Optical components: enabling compact polarizers and polarizing beam-splitters, wave retarders, lenses, etc.
- Gratings and spectrometry: providing control for energy distribution and high diffraction efficiency and enabling compact spectrometers.
- Polarimetry: enabling spatial multiplexing for compact polarimeters.
- Data communications: enabling wavefront multiplexing for LiFi.
- Lighting: enhancing and controlling LED emission.
- Anti-counterfeiting: allowing holographic marks, difficult to replicate and potentially invisible to the naked eye.
- Photolithography: focusing light near the diffraction limit
- A solution for optical component miniaturization and compact integration in optoelectronic devices: Flat optics components are typically smaller in volume and weight, and thinner.
- Can be made to leverage existing nano-fabrication, integration and assembly trends, such as photolithography, nano-imprint lithography, “wafer-level optics” and possibly even wafer and panel level processing.
- Offers the opportunity for less complex device fabrication and packaging workflows compared to existing solutions. There is the potential for mass integration, right in line with current nano- and micro- device fabrication along with wafer and panel level packaging. This would significantly reduce the need for costly, time consuming optical assembly.
- Overall system costs should be comparable or even lower than traditional ones.