The rising production and consumption of data worldwide is posing challenges on how it can be efficiently analyzed and absorbed on a human scale. Emerging technologies in data visualization are rapidly expanding to try to address this problem. One technology in particular, Augmented Reality (AR) glasses, has the capacity to allow individuals to process live virtual information while keeping an eye on their surrounding environment. Our team has recently presented a unique retinal projection concept for augmented reality applications1. The concept combines a photonic integrated circuit (PIC) and holography. The photonic integrated circuit is made of silicon nitride (Si3N4) for its ability to guide visible wavelengths2 (λ = 532 nm in our case) and its compatibility with the CMOS fabrication process technology. In our concept, the role of this circuit is to distribute and extract light at specific locations on the surface of a glass. The light emissions pass through a holographic layer deposited on the surface of the photonic circuit. The holographic layer is made of a 2D array of small individual holograms. The role of the hologram is to modify the light properties (emission angle, phase…) of the light emissions from the PIC in order to generate a composite plane wavefront. The eye can focus this wavefront on the retina even at a small eye relief distance (few centimeters). The focused wavefront represents one pixel of the projected retinal image. Several emissive point distributions on the surface of the PIC will create a full 2D retinal image. The retinal projector concept is schematically described in fig.1. Until now, both parts of the AR glass – the PIC and the holographic layer – have been developed independently3,4,5. In previous work6, the basic building blocks of the circuit were designed both analytically and with numerical simulations: single-mode waveguide, MMI (MultiMode Interference) coupler, diffraction gratings and more. This paper presents in section 2 the design and numerical simulations of a double-tip edge coupler at λ = 532 nm. This additional component will be useful to couple light in our future prototypes with a compact design. In section 3, it is combined with previously designed PIC building blocks to design a unique device dedicated to evaluate the interaction between a silicon nitride PIC and a hologram.
In this paper we present the use of a 300mm Si-Photonic platform for applications beyond the data communication. Beam steering and beam shaping for free-space-optics and hybrid III - V/ Si optical switch for computing applications are discussed.
Abstract Three dimensional sensing is essential in order that machines may operate in and interact with complex dynamic environments. Solid-state beam scanning devices are seen as being key to achieving required system specifications in terms of sensing range, resolution, refresh rate and cost. Integrated optical phased arrays fabricated on silicon wafers are a potential solution, but demonstrated devices with system-level performance currently rely on expensive widely tunable source lasers. Here, we combine silicon nitride photonics and micro-electromechanical system technologies, demonstrating the integration of an active photonic beam-steering circuit into a piezoelectric actuated micro cantilever. An optical phased array, operating at a wavelength of 905 nm, provides output beam scanning over a range of 17° in one dimension, while the inclination of the entire circuit and consequently the angle of the output beam in a second dimension can be independently modified over a range of up to 40° using the piezoelectric actuator.
We report on the characterization of a high channel count Optical Phased Array (OPA) at the wafer level. Using a modified prober, a 256 channel OPA has been successfully calibrated for +/-25° without requiring any packaging steps thus allowing for fast OPA testing.
An integrated photon pair source in the 1550-nm wavelength region is demonstrated. Spontaneous four-wave mixing is facilitated through a silicon-on-insulator micro-ring filter with 125-GHz spaced resonances. Coincidences in the pair emission are observed with a 95% visibility at spectral channels equidistant to the pump wavelength.
Abstract Optical phased arrays (OPAs) with the ability of dynamic beam-steering hold great promise for industrial applications. Although they potentially offer high-resolution, high-speed and wide-angle beam-steering, 2D beam-steering has only been achieved by 1D OPAs with wavelength-tuning or by 2D OPAs containing enormous numbers of elements, thereby significantly increasing the system complexity and power consumption. Here we demonstrate a liquid-crystal-tunable Bragg-reflector waveguide outcoupler integrated with a 1D OPA. The output beam angle is controlled by an electric-field applied to the liquid crystal between the Bragg-mirrors, independently from steering along a second axis with the OPA. Our proof-of-concept demonstration with an 8-channel OPA shows 2D beam-steering with a 16° × 15° field-of-view and 12 ms × 14 μs time-response. Our approach opens a practical way for scalable OPAs capable of single wavelength 2D beam-steering, as well as demonstrating a strategy for the integration of liquid crystal materials with silicon photonics.
We report performances of active and passive devices in a Silicon-Photonic library on a 300mm-CMOS-platform, showing highly uniform behavior of passive WDM devices, Mach-Zehnder modulators and germanium photo-detectors with state of the art performances.
For several years, there has been a diversification of applications addressed by silicon photonics. Historically intended for telecom applications, silicon photonic platforms must now address the needs of transceivers for Data Center Interconnect, 5G backhaul / fronthaul but also those of emerging applications such as circuitry for LiDAR or for high performance computing (Artificial Intelligence, Quantum Computing). In order to meet this growing demand and the diversity of needs accompanying all these applications, CEA LETI has developed a new silicon photonics platform based on 300mm SOI wafers. This development is based in part on the experience acquired over more than 15 years on 200mm technology. Switching to 300mm equipment allows access to more advanced and above all, much more stable manufacturing tools, thus making it possible to envisage the production of complex circuits and large-scale integration of photonic components. For the most critical mask levels, the use of an immersion lithography stepper supported by OPC algorithms dedicated to photonics also opens up new perspectives in the possibilities of component design. In this presentation we will describe this new platform by going through its constituent modules and highlighting application versatility. Characterization results of various components fabricated on this platform will also be presented.
