Here we demonstrate a spectrally broadband, gigahertz-fast Mach–Zehnder interferometric modulator exhibiting a miniscule V π L of 95 V ⋅ µ m , deploying a subwavelength short electrostatically tunable plasmonic phase shifter based on heterogeneously integrated indium tin oxide thin films into silicon photonics.

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 deterministic transfer methods of 2D materials onto an arbitrary substrate deploy viscoelastic stamping. However, these methods produce (a) significant cross-contamination of the substrate inherent from typical dense sources of 2D material flakes and (b) are challenged with respect to spatial alignment, and (c) multi-transfer at a single step. 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 printer-method results in an aerial cross-contamination improvement of two to three orders of magnitude relative to state-of-the-art transfer methods from a source of average area for single flake (~50 µ m ² ). 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. We further demonstrate functional devices such as Graphene tunnel junctions and transistors, and TMD-based material tunable microring resonators. 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 (TMDCs), 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 TMDC-ring based hybrid platform where resonance shift has been mapped out as a function of flake thickness, which correlates well with our simulated data. These experimental findings on passive TMDC-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 2D materials such as transition metal dichalcogenides (TMDs) 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. The control and understanding of the precise value of the optical index of these materials, however, is challenging, as the standard metrology techniques such as the millimeter‐large ellipsometry is often not usable due the small lateral 2D material flake dimension. Here, we demonstrate an approach of passive tunable coupling by integrating few layers of MoTe ₂ onto a microring resonator connected to a waveguide bus. We find the TMD‐to‐ring circumference coverage length ratio required to precisely place the ring into a critical coupling condition to be about 10% as determined from the variation of spectral resonance visibility and loss as a function of TMD coverage. Using this TMD‐ring heterostructure, we further demonstrate a semiempirical method to determine the index of a 2D material ( n _MoTe2 of 4.36+0.011 i ) near telecommunication‐relevant wavelength. The placement, control, and optical property understanding of 2D materials with integrated photonics pave the way for further studies of active 2D material‐based optoelectronics and circuits.

Photodetectors are key optoelectronic building blocks performing the essential optical-to-electrical signal conversion, and unlike solar cells, operate at a specific wavelength and at high signal or sensory speeds. Towards achieving high detector performance, device physics, however, places a fundamental limit of the achievable detector sensitivity, such as responsivity and gain, when simultaneously aimed to increasing the detector’s temporal response (speed) known as the gain-bandwidth product (GBP). While detector’s GBP has been increasing in recent years, the average GBP is still relatively modest (∼10⁶-10⁹ Hz-A/W). Here we discuss photoconductor-based detector performance limits and opportunities based on arguments from scaling length theory relating photocarrier channel length, mobility, electrical resistance with optical waveguide mode constrains. We show that short-channel detectors are synergistic with slot-waveguide approaches, and when combined, offer a high-degree of detector design synergy especially for the class of nanometer-thin materials. Indeed, we find that two-dimensional material-based detectors are neither limited by their low mobility nor by associated carrier velocity saturation limitations and can, in principle, allow for 100 GHz fast response rates, which is unlike traditional detector designs that are based on wide channel lengths. However, the contact resistance is still a challenge for such thin photo absorbing materials – a research topic that is still not addressed yet. An interim solution is to utilize heterojunction approaches for functionality separation. Nonetheless, atomistic and nanometer-thin materials used in such next-generation scaling length theory based detectors also demand high material quality and monolithic integration strategies into photonic circuits including foundry-near processes. As it stands, this letter aims to guide the community if achieving the next generation photodetectors aiming for a performance target of GBP ∼ 10¹² Hz-A/W.