Precision and chip contamination-free placement of two-dimensional (2D) materials is expected to accelerate both the study of fundamental properties and novel device functionality. Current transfer methods of 2D materials onto an arbitrary substrate deploy wet chemistry and viscoelastic stamping. However, these methods produce a) significant cross contamination of the substrate due to the lack of spatial selectivity b) may not be compatible with chemically sensitive device structures, and c) are challenged with respect to spatial alignment. Here, we demonstrate a novel method of transferring 2D materials resembling the functionality known from printing; utilizing a combination of a sharp micro-stamper and viscoelastic polymer, we show precise placement of individual 2D materials resulting in vanishing cross contamination to the substrate. Our 2D printermethod results show an aerial cross contamination improvement of two to three orders of magnitude relative to state-of-the-art dry and direct transfer methods. Moreover, we find that the 2D material quality is preserved in this transfer method. Testing this 2D material printer on taped-out integrated Silicon photonic chips, we find that the micro-stamper stamping transfer does not physically harm the underneath Silicon nanophotonic structures such as waveguides or micro-ring resonators receiving the 2D material. Such accurate and substrate-benign transfer method for 2D materials could be industrialized for rapid device prototyping due to its high time-reduction, accuracy, and contamination-free process.

Layered two-dimensional (2D) materials provide a wide range of unique properties as compared to their bulk counterpart, making them ideal for heterogeneous integration for on-chip interconnects. Hence, a detailed understanding of the loss and index change on Si integrated platform is a prerequisite for advances in opto-electronic devices impacting optical communication technology, signal processing, and possibly photonic-based computing. Here, we present an experimental guide to characterize transition metal dichalcogenides (TMDs), once monolithically integrated into the Silicon photonic platform at 1.55 µm wavelength. We describe the passive tunable coupling effect of the resonator in terms of loss induced as a function of 2D material layer coverage length and thickness. Further, we demonstrate a TMD-ring based hybrid platform as a refractive index sensor where resonance shift has been mapped out as a function of flakes thickness which correlates well with our simulated data. These experimental findings on passive TMD-Si hybrid platform open up a new dimension by controlling the effective change in loss and index, which may lead to the potential application of 2D material based active on chip photonics.

Atomically thin two-dimensional (2D) materials provide a wide range of basic building blocks with unique properties, making them ideal for heterogeneous integration with a mature chip platform for advances in optical communication technology. Control and understanding of the precise value of the optical index of these materials, however, is challenging, due to the small lateral flake dimension. Here we demonstrate a semiempirical method to determine the index of a 2D material (nMoTe2 of 4.36+0.011i) near telecommunicationrelevant wavelength by integrating few layers of MoTe2 onto a micro-ring resonator. The placement, control, and optical-property understanding of 2D materials with integrated photonics paves a way for further studies of active 2D material-based optoelectronics and circuits.

Here we discuss the physics of electro-optic modulators deploying 2D materials. We include a scaling laws analysis showing how energy-efficiency and speed change for three underlying cavity systems as a function of critical device length scaling. A key result is that the energy-per-bit of the modulator is proportional to the volume of the device, thus making the case for submicron-scale modulators possible deploying a plasmonic optical mode. We then show how Graphene's Pauli-blocking modulation mechanism is sensitive to the device operation temperature, whereby a reduction of the temperature enables a 10x reduction in modulator energy efficiency. Furthermore, we show how the high index tunability of Graphene is able to compensate for the small optical overlap factor of 2D-based material modulators, which is unlike classical Silicon-based dispersion devices. Lastly we demonstrate a novel method towards a 2D material printer suitable for crosscontamination free and on-demand printing. The latter paves the way to integrate 2D materials seamlessly into taped-out photonic chips.

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