High-efficiency metalenses for optical sensors

June 23, 2021 // By Nick Flaherty
High-efficiency metalenses for optical sensors
The wafer-level diffractive optics business of II‐VI has launched a high-efficiency multifunctional metalenses based on its own proprietary platform.

The II-VI metalenses enable smaller optical sensors with VCSEl vertical lasers in applications in consumer electronics, automotive, life sciences, and industrial markets.

Optical sensors are increasingly embedded in diverse products such as smartphones, automotive vehicles, medical diagnostics, and laser processing heads, driving the demand for more efficient miniature optical subsystems that are compact, reliable, and manufacturable at scale.

The II-VI metalenses are flat diffractive optical elements (DOEs) that are flat and can achieve multiple optical functions with extremely high efficiency on a single surface for a broad range of wavelengths. In one implementation, the metalens both collimates and splits the light from vertical cavity surface-emitting lasers (VCSELs) into a highly uniform grid of thousands of infrared beams that are projected on the scene. Optical sensors reference these grids to accurately construct the scene in three dimensions.

The DOEs are lithographically patterned and offer complete phase control of transmitted light without limitations imposed by refractive optics. A micron-thick active phase-transforming layer is directly etched into chemically inert dielectrics on robust fused silica substrate. An organics-free material platform is characterized by excellent reliability and can withstand harsh environmental conditions, high optical power and temperatures up to 500°C.

Fabrication is based on robust deep ultraviolet (DUV) photolithography and a reactive ion etch process. Wafer-scale DOE optics are mass- produced using teh same volume fabrication methods as the electronic IC industry and the process scales to multiple millions of micro-optical devices per year.

“The high reliability of our glass-based DOEs are field-proven, as part of our optical communications products that we have been shipping in volume for years,” said Dr. Sanjai Parthasarathi, Chief Marketing Officer at II-VI. “Furthermore, our metalenses can be utilized with our VCSELs to enable differentiated ultracompact 3D sensing cameras, spurring broader adoption in consumer electronics and automotive.”

The II-VI portfolio for sensing includes infrared VCSEL chips, including multi-junction designs, from one to hundreds of emitters. II-VI VCSEL arrays are designed for low-cost non-hermetic packaging and can be reliably and cost-effectively scaled in total power by increasing the number of emitters per chip. II-VI VCSEL arrays are available as chips or integrated with DOEs in surface-mountable modules. II-VI’s DOEs include lenses, micro-lens arrays, diffusers, and splitters. II-VI also offers thin-film filters that are used to improve the signal-to-noise ratio of image sensor arrays.


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