Smartphone Generated Holograms Are One Sensor Closer

Researchers at the Korea Institute of Science and Technology (KIST) have created 3D digital holograms, by developing a polarisation image sensor with no additional polarisation filter. With the further miniaturisation of the holographic camera sensor module, the researchers believe this could lead to holograms generated by smartphones.

KIST has recently announced that a research team led by Dr. Min-Chul Park and Dr Do Kyung Hwang of the Center for Opto-Electronic Materials and Devices, in collaboration with a research team led by Prof Seongil Im of the Department of Physics at Yonsei University, has successfully developed a photodiode that detects the polarisation of light in the near-infrared region without additional polarisation filters.

With this approach, the team has been able to produce a miniaturised holographic image sensor for 3D digital holograms, using the 2D semiconductor materials rhenium diselenide and tungsten diselenide. The work is published in ACS Nano1.

Photodiodes, which convert light into electrical signals, are essential components within the pixels of image sensors in digital and smartphone cameras. Introducing the ability to sense the polarisation of light to the image sensor of an ordinary camera provides a variety of new information, enabling the storage of 3D holograms.

Previous polarisation-sensing cameras have needed an additional polarisation filter, several hundred micrometres in size, attached to an ultra-small optical diode image sensor, less than a micrometre in size. Thus, they could not be implemented into portable electronic devices due to the difficulties of integration and miniaturisation.

The research group developed a photodiode by stacking an n-type semiconductor, rhenium diselenide, which exhibits a difference in light absorption dependent on the linear polarisation angle of light in the near-infrared (980 nm) region, and a p-type semiconductor, tungsten diselenide, which exhibits no difference in photo-response dependent on polarisation, but enables superior performance.

The device performs well in the photodetection of various wavelengths from ultraviolet to near-infrared, even capable of selectively detecting the polarisation characteristics of light in the near-infrared region. The research group utilised the device to create a digital holographic image sensor that records polarisation characteristics to capture holograms.

Dr Hwang of KIST commented that ‘research on the downsizing and integration of individual elements is required to ultimately miniaturise holographic systems. The results of our research will lay the foundation for the future development of miniaturised holographic camera sensor modules.’

Dr Park added: ‘the new sensor can further detect near-infrared light, as well as previously undetectable visible light, opening up new opportunities in various fields such as 3D night vision, self-driving, biotechnology, and near-infrared data acquisition for analysing and restoring cultural assets.

1 - https://pubs.acs.org/doi/10.1021/acsnano.1c06234