Dense silicon-nitride PIC design and manufacturing on transparent substrate for a retinal projector evaluation

Millard, Kyllian; Meynard, Basile; Lee, Yann; Colard, Matthias; Faugier-Tovar, Jonathan; Dujaili, Haidar Al; Lartigue, Olivier; Fowler, Daivid; Ghibaudo, Elise; Martinez, Christophe

doi:10.1117/12.2605816

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…We estimate propagation losses using Payne and Lacey's formalism 21 with a Line Edge Roughness (LER) of 4.8 nm. We obtain this experimental data out of a sidewall roughness measurement performed on a previous generation of SiN photonics circuits designed for the same wavelength 22 . Propagation losses are expressed in 𝑚 −1 by…”

Section: Performance Estimationmentioning

confidence: 99%

Multilayer photonic-integrated circuit design for dense random waveguide distribution addressing, application to near-eye display

Millard

Rainouard

Fowler

et al. 2023

Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) IV

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Near-eye displays have become a technology of high interest for Augmented, Virtual and Mixed reality due to the unique immersive experience they provide to the user. The majority of these devices use macroscopic optical elements that make them bulky and heavy. Our team has proposed a disruptive near-eye display concept that uses the self-focusing effect to project an image to the user's retina. To form an image, emissive points are generated from a dense photonic integrated circuit embedded within the lens of a pair of smart glasses. In this work, we present the design of a dense routing architecture that addresses thousands of randomly distributed emissive points from a few hundred inputs. The circuit combines unbalanced waveguide splitter trees with a non-periodical addressing onto a dense waveguide network. We present the design optimization through numerical simulations and estimate the overall device performance based on simulation results. A waveguide interlayer crossing simulation indicates losses better than 0.003 dB/crossing, which guarantees low optical losses over thousands of crossings. By unbalancing correctly the splitter trees, we can obtain homogeneous power profiles over an emissive point distribution. The experimental validation of our design will be a major step towards the elaboration of a first prototype.

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Section: Performance Estimationmentioning

confidence: 99%

Multilayer photonic-integrated circuit design for dense random waveguide distribution addressing, application to near-eye display

Millard

Rainouard

Fowler

et al. 2023

Optical Architectures for Displays and Sensing in Augmented, Virtual, and Mixed Reality (AR, VR, MR) IV

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“…The measurement of active light extraction in our transparent sample shown in Figure 8 is complex due to parasitic reflections and propagation losses in our Si2N3 waveguides 8 . The useful signal from the extraction quickly becomes noisy.…”

Section: Structurementioning

confidence: 99%

Study and validation of switchable grating using liquid crystal for active waveguide addressing

Toubi

Colard

Lee

et al. 2023

Emerging Liquid Crystal Technologies XVIII

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In our Augmented Reality (AR) project, we are investigating the use of a retinal projection display based on the association of pixelated holograms and a dense distribution of waveguides. We study the use of gratings impregnated with liquid crystal to actively extract light from waveguides. We explore two extraction strategies: tuning the refractive index contrast between the grating teeth and grooves to erase the grating diffraction effect, and changing the index of the waveguide cladding to tune the evanescence of the guided mode. Firstly, we present and discuss the measurements of the diffraction efficiency of nano-imprint gratings impregnated with liquid crystal and refractive liquid index. Secondly, we discuss the results of integrated switchable extraction grating of the second strategy.

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“…They allow the division of the input signal from the laser, into a multitude of waveguides densely distributed at the surface of the glass. The manufacturing process of the waveguide was introduced recently 12 and we present in PW23 our very latest results concerning the conception of advanced routing architectures, used for addressing dense random distributions of waveguides 13 As described in Figure 2(b), a switchable out-coupler grating extracts the light guided in the SiN waveguide at a specific location given by the intersection of a waveguide and an electrode. To achieve this, we use a grating impregnated with a Liquid Crystal.…”

Section: Pixelated Holographic Displaymentioning

confidence: 99%

Evaluation of a pixelated holographic display concept for a near-eye display: recent results and technological developments

Martinez

Colard²,

Fowler³

et al. 2023

Advances in Display Technologies XIII

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The development of an ideal optical system to support Mixed Reality and Augmented Reality (AR) applications has raised a lot of interest in the scientific community in the last decades. The perfect device remains an inaccessible target and researchers have to focus on the optimization of some specific behaviors. Several years ago, we introduced a disruptive display concept to push the device integration to the limit, with the suppression of the optical system. This allows the imaging process to be considered in a different way with a specific monitoring of the field of view. With this ‘smart glass’ concept, the glass is the display, and the image is formed directly onto the retina with a combination of refractive and diffractive effects. This conceptual target allowed us to define a technological roadmap to support our development. Technologies involved in this concept concern principally the field of Photonic Integrated Circuits in the visible range, digital/analogic holography and Liquid Crystal devices. We will present the current state of our research with a particular focus on the holographic display element. Recent results related to analogic pixelated hologram recording validate and question both our technological and conceptual approach. We will show images formed by sparse holographic pixel distributions with controlled angular characteristics that demonstrate the mix of refractive and diffractive effects. The transmission behavior of this holographic device will also be analyzed.

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Dense silicon-nitride PIC design and manufacturing on transparent substrate for a retinal projector evaluation

Cited by 7 publications

References 19 publications

Multilayer photonic-integrated circuit design for dense random waveguide distribution addressing, application to near-eye display

Multilayer photonic-integrated circuit design for dense random waveguide distribution addressing, application to near-eye display

Study and validation of switchable grating using liquid crystal for active waveguide addressing

Evaluation of a pixelated holographic display concept for a near-eye display: recent results and technological developments

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