We leverage nanophotonics to create novel miniaturized optical systems. Our mission is to (1) investigate nanoscale light-matter interactions at the material, device and system levels and (2) push the state-of-the-art in performance and functionality of optical devices to advance future biomedical, sensing, communication, and computing technologies.

Nanophotonics Platform:

Nanophotonic devices have features on the order of the wavelength of light, which enables control of the flow of light with extreme precision (beyond the diffraction limit) and scalability on a chip. This platform, particularly silicon photonics, has already been transformative for transferring high bandwidth information in data centers today. These optical circuits use the coherent control of light in waveguides to enable functionalities such as strong light enhancement in microresonators, the manipulation of the many degrees of freedom of light (time, space, frequency, polarization), and fast and efficient optical modulation. In addition, these optical circuits can be printed on a chip using the same nanofabrication tools in the electronics industry for low-cost mass manufacturing.

Core Research Areas:

Implantable and Wearable Neural and Biomedical Optical Interfaces

Light is a powerful tool for interrogating and manipulating biological systems, enabling targeted stimulation, sensing, and imaging. The study of neural circuits and encoding, for example, has been transformed by optical methods like optogenetics and functional imaging, which make it possible to control and read neural activity using light, enabling remarkable experiments in which light controls the walking behavior of mice or even the memory of songbirds. However, current optical stimulation and sensing devices rely on bulk table-top optics, limiting their access deep within living and moving biological systems due to their size and weight. Additionally, the ability to flexibly address neurons with single-cell resolution and sub-millisecond timescales across the many regions and hierarchies of the brain has remained a longstanding challenge. Building miniaturized optical tools will enable new neuromodulation and behavior studies of underlying neural circuits to better inform our understanding of neurodegenerative diseases and mental illness.

We are designing nanophotonic systems compact enough to be placed on the tip of a needle for 3D light projection and sensing on implantable probes and wearable biomedical devices, prostheses, and next generation brain-machine-interfaces. We are bringing functionalities including 3D volumetric beam shaping, sub-diffraction limit resolutions, and highly parallelized interferometric/spectroscopic sensing to neural and biomedical devices. We are developing new optical devices and understanding their underlying physics to address the challenges that come with this goal including photonic platforms working outside of the traditional telecommunications wavelengths (e.g. below 1300 nm), integration with electronic systems, ultra-low power optical circuits, wireless control, and flexible devices for better biocompatibility.

Our recent demonstration of a nanophotonic optogenetic neural probe based on a reconfigurable visible wavelength switching network can be found here. Works on miniaturizing optical imaging systems for fluorescence-based endoscopy and optical coherence tomography (OCT) can be found here and here.

Chip-scale 3D Optical Beam Shaping and Sensing

In the age of self-driving cars and automation, optical sensors that can project light in 3D and remotely map an environment are essential at all scales, from long-range distances while driving or sensing chemicals in the air down to the microscales relevant for sensing pathogens within the bloodstream. Current methods to dynamically steer or pattern light require bulk table-top optics such as mechanical rotating galvo mirrors or non-mechanical devices (i.e. acousto-optic deflectors and spatial light modulators). In contrast, nanophotonic optical phased arrays and metasurfaces rely on a set of phase-controlled coherent optical antennas that allow for beam shaping including steering and focusing of light from a compact chip. This forms the basis of today’s chip-scale LiDAR which has gained recent interest for mapping our surroundings in 3D.

We are currently expanding the capabilities of this platform at non-traditional wavelength ranges for applications in biological stimulation and sensing, remote sensing, portable displays for augmented and virtual reality, and optical trapping of atoms and molecules. We are investigating new photonic structures and mechanisms for chip-scale beam shaping to address current challenges in scalability and high performance in scattering and turbulent environments.

Our recent demonstrations of chip-scale beam steering at blue and infrared wavelengths can be found here and here.

Quantum and Emerging Computing and Communication Systems

Optical quantum information processing (QIP) has the potential to transform how we transfer information securely, solve large intractable problems, and improve sensing using the quantum nature of light with resources such as high dimensional entanglement. Quantum optical communication systems in particular require coherent control over a large number of single-photon sources and optical channels, driving the miniaturization of large table-top quantum optical systems to the chip-scale to make its practical and commercial implementation possible. In addition, photons provide a temperature-insensitive quantum platform meaning properties like quantum entanglement and optical squeezing can be also be used to enhance sensing techniques in living (often hot) biological systems. Similarly, in the classical domain, machine learning tasks are driving the need for new hardware paradigms that can efficiently execute neural networks, and optical circuits have the potential to provide the high-bandwidth parallelism that is needed.

We are currently working on optical building blocks that can manipulate different degrees of freedom (time, frequency and transverse spatial modes) of light to drastically scale up the number of channels within a single waveguide and address a large array of quantum emitters. Encoding within these high-dimensional degrees of freedom can reduce the footprint of the overall system, reduce losses, and relieve resource requirements for the quantum photon sources and detectors.

Our work on using the transverse spatial mode degree of freedom for quantum interference can be found here.