Harvard SEAS Researchers Develop First Tunable On-Chip Twisted Moiré Photonic Crystal Sensor

A team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with Stanford University and the University of California – Berkeley, has developed the first tunable on-chip twisted moiré photonic crystal sensor, capable of simultaneously measuring both wavelength and polarization. This innovation offers a transformative path toward more compact, precise, and energy-efficient optical devices.>

Twisted moiré photonic crystals are a type of optical metamaterial consisting of two or more overlapping photonic crystal layers. When these layers are twisted at specific angles and distances, they generate interference patterns that can be fine-tuned to manipulate different characteristics of light. The Harvard-led team integrated these crystals into a miniature sensor using microelectromechanical systems (MEMS) to actively control the rotation and spacing between layers in real time.

“Twisted moiré photonic crystals are promising for engineering smaller, more powerful optical systems because they offer highly tunable optical properties, precise light control, compact and scalable design, and broad application potential across various advanced photonic technologies,” said Eric Mazur, Balkanski Professor of Physics and Applied Physics at SEAS.

The entire sensor is only a few millimeters across and was fabricated using CMOS-compatible processes, making it suitable for mass production. Its design places photonic crystal layers on vertical and rotary actuators connected to an electrode, allowing the device to adjust the gap and angle between the layers precisely.

This active tunability enabled the device to perform both hyperspectral and hyperpolarimetric imaging—where each captured pixel includes detailed information about both the electromagnetic spectrum and the polarization state of light. It is the first such device to combine these measurements using dynamic, real-time tuning.

“Our research demonstrates how powerful these materials can be when we have precise control and establishes a scalable path towards creating comprehensive flat-optics devices suitable for versatile light manipulation and information processing tasks,” said Haoning Tang, postdoctoral fellow at SEAS and first author of the study.

Potential applications of the sensor include quantum computing, data communications, remote sensing, and medical imaging—anywhere light analysis must be both detailed and compact. In future iterations, the team envisions enhanced tuning capabilities with even more degrees of freedom.

The research was published in Nature Photonics and supported by the National Science Foundation, DARPA, the U.S. Air Force Office of Scientific Research, and the U.S. Office of Naval Research. Fabrication was conducted at the Harvard University Center for Nanoscale Systems, a member of the National Nanotechnology Coordinated Infrastructure Network.

Source/Photo Credit:
Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS)  

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